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47<p class="text-center"><a href="command-line-options.html#adaptive-blur">‑adaptive‑blur</a> • <a href="command-line-options.html#adaptive-resize">‑adaptive‑resize</a> • <a href="command-line-options.html#adaptive-sharpen">‑adaptive‑sharpen</a> • <a href="command-line-options.html#adjoin">‑adjoin</a> • <a href="command-line-options.html#affine">‑affine</a> • <a href="command-line-options.html#alpha">‑alpha</a> • <a href="command-line-options.html#annotate">‑annotate</a> • <a href="command-line-options.html#antialias">‑antialias</a> • <a href="command-line-options.html#append">‑append</a> • <a href="command-line-options.html#attenuate">‑attenuate</a> • <a href="command-line-options.html#authenticate">‑authenticate</a> • <a href="command-line-options.html#auto-gamma">‑auto‑gamma</a> • <a href="command-line-options.html#auto-level">‑auto‑level</a> • <a href="command-line-options.html#auto-orient">‑auto‑orient</a> • <a href="command-line-options.html#backdrop">‑backdrop</a> • <a href="command-line-options.html#background">‑background</a> • <a href="command-line-options.html#bench">‑bench</a> • <a href="command-line-options.html#bias">‑bias</a> • <a href="command-line-options.html#black-point-compensation">‑black‑point‑compensation</a> • <a href="command-line-options.html#black-threshold">‑black‑threshold</a> • <a href="command-line-options.html#blend">‑blend</a> • <a href="command-line-options.html#blue-primary">‑blue‑primary</a> • <a href="command-line-options.html#blue-shift">‑blue‑shift</a> • <a href="command-line-options.html#blur">‑blur</a> • <a href="command-line-options.html#border">‑border</a> • <a href="command-line-options.html#bordercolor">‑bordercolor</a> • <a href="command-line-options.html#borderwidth">‑borderwidth</a> • <a href="command-line-options.html#brightness-contrast">‑brightness‑contrast</a> • <a href="command-line-options.html#cache">‑cache</a> • <a href="command-line-options.html#canny">‑canny</a> • <a href="command-line-options.html#caption">‑caption</a> • <a href="command-line-options.html#cdl">‑cdl</a> • <a href="command-line-options.html#channel">‑channel</a> • <a href="command-line-options.html#charcoal">‑charcoal</a> • <a href="command-line-options.html#chop">‑chop</a> • <a href="command-line-options.html#clamp">‑clamp</a> • <a href="command-line-options.html#clip">‑clip</a> • <a href="command-line-options.html#clip-mask">‑clip‑mask</a> • <a href="command-line-options.html#clip-path">‑clip‑path</a> • <a href="command-line-options.html#clone">‑clone</a> • <a href="command-line-options.html#clut">‑clut</a> • <a href="command-line-options.html#coalesce">‑coalesce</a> • <a href="command-line-options.html#colorize">‑colorize</a> • <a href="command-line-options.html#colormap">‑colormap</a> • <a href="command-line-options.html#color-matrix">‑color‑matrix</a> • <a href="command-line-options.html#colors">‑colors</a> • <a href="command-line-options.html#colorspace">‑colorspace</a> • <a href="command-line-options.html#combine">‑combine</a> • <a href="command-line-options.html#comment">‑comment</a> • <a href="command-line-options.html#compare">‑compare</a> • <a href="command-line-options.html#complex">‑complex</a> • <a href="command-line-options.html#compose">‑compose</a> • <a href="command-line-options.html#composite">‑composite</a> • <a href="command-line-options.html#compress">‑compress</a> • <a href="command-line-options.html#connected-components">‑connected‑components</a> • <a href="command-line-options.html#contrast">‑contrast</a> • <a href="command-line-options.html#contrast-stretch">‑contrast‑stretch</a> • <a href="command-line-options.html#convolve">‑convolve</a> • <a href="command-line-options.html#copy">‑copy</a> • <a href="command-line-options.html#crop">‑crop</a> • <a href="command-line-options.html#cycle">‑cycle</a> • <a href="command-line-options.html#debug">‑debug</a> • <a href="command-line-options.html#decipher">‑decipher</a> • <a href="command-line-options.html#deconstruct">‑deconstruct</a> • <a href="command-line-options.html#define">‑define</a> • <a href="command-line-options.html#delay">‑delay</a> • <a href="command-line-options.html#delete">‑delete</a> • <a href="command-line-options.html#density">‑density</a> • <a href="command-line-options.html#depth">‑depth</a> • <a href="command-line-options.html#descend">‑descend</a> • <a href="command-line-options.html#deskew">‑deskew</a> • <a href="command-line-options.html#despeckle">‑despeckle</a> • <a href="command-line-options.html#direction">‑direction</a> • <a href="command-line-options.html#displace">‑displace</a> • <a href="command-line-options.html#display">‑display</a> • <a href="command-line-options.html#dispose">‑dispose</a> • <a href="command-line-options.html#dissimilarity-threshold">‑dissimilarity‑threshold</a> • <a href="command-line-options.html#dissolve">‑dissolve</a> • <a href="command-line-options.html#distort">‑distort</a> • <a href="command-line-options.html#distribute-cache">‑distribute‑cache</a> • <a href="command-line-options.html#dither">‑dither</a> • <a href="command-line-options.html#draw">‑draw</a> • <a href="command-line-options.html#duplicate">‑duplicate</a> • <a href="command-line-options.html#edge">‑edge</a> • <a href="command-line-options.html#emboss">‑emboss</a> • <a href="command-line-options.html#encipher">‑encipher</a> • <a href="command-line-options.html#encoding">‑encoding</a> • <a href="command-line-options.html#endian">‑endian</a> • <a href="command-line-options.html#enhance">‑enhance</a> • <a href="command-line-options.html#equalize">‑equalize</a> • <a href="command-line-options.html#evaluate">‑evaluate</a> • <a href="command-line-options.html#evaluate-sequence">‑evaluate‑sequence</a> • <a href="command-line-options.html#extent">‑extent</a> • <a href="command-line-options.html#extract">‑extract</a> • <a href="command-line-options.html#family">‑family</a> • <a href="command-line-options.html#features">‑features</a> • <a href="command-line-options.html#fft">‑fft</a> • <a href="command-line-options.html#fill">‑fill</a> • <a href="command-line-options.html#filter">‑filter</a> • <a href="command-line-options.html#flatten">‑flatten</a> • <a href="command-line-options.html#flip">‑flip</a> • <a href="command-line-options.html#floodfill">‑floodfill</a> • <a href="command-line-options.html#flop">‑flop</a> • <a href="command-line-options.html#font">‑font</a> • <a href="command-line-options.html#foreground">‑foreground</a> • <a href="command-line-options.html#format">‑format</a> • <a href="command-line-options.html#format_identify_">‑format[identify]</a> • <a href="command-line-options.html#frame">‑frame</a> • <a href="command-line-options.html#frame_import_">‑frame[import]</a> • <a href="command-line-options.html#function">‑function</a> • <a href="command-line-options.html#fuzz">‑fuzz</a> • <a href="command-line-options.html#fx">‑fx</a> • <a href="command-line-options.html#gamma">‑gamma</a> • <a href="command-line-options.html#gaussian-blur">‑gaussian‑blur</a> • <a href="command-line-options.html#geometry">‑geometry</a> • <a href="command-line-options.html#gravity">‑gravity</a> • <a href="command-line-options.html#grayscale">‑grayscale</a> • <a href="command-line-options.html#green-primary">‑green‑primary</a> • <a href="command-line-options.html#hald-clut">‑hald‑clut</a> • <a href="command-line-options.html#help">‑help</a> • <a href="command-line-options.html#highlight-color">‑highlight‑color</a> • <a href="command-line-options.html#hough-lines">‑hough‑lines</a> • <a href="command-line-options.html#iconGeometry">‑iconGeometry</a> • <a href="command-line-options.html#iconic">‑iconic</a> • <a href="command-line-options.html#identify">‑identify</a> • <a href="command-line-options.html#ift">‑ift</a> • <a href="command-line-options.html#immutable">‑immutable</a> • <a href="command-line-options.html#implode">‑implode</a> • <a href="command-line-options.html#insert">‑insert</a> • <a href="command-line-options.html#intensity">‑intensity</a> • <a href="command-line-options.html#intent">‑intent</a> • <a href="command-line-options.html#interlace">‑interlace</a> • <a href="command-line-options.html#interpolate">‑interpolate</a> • <a href="command-line-options.html#interline-spacing">‑interline‑spacing</a> • <a href="command-line-options.html#interword-spacing">‑interword‑spacing</a> • <a href="command-line-options.html#kerning">‑kerning</a> • <a href="command-line-options.html#kuwahara">‑kuwahara</a> • <a href="command-line-options.html#label">‑label</a> • <a href="command-line-options.html#lat">‑lat</a> • <a href="command-line-options.html#layers">‑layers</a> • <a href="command-line-options.html#level">‑level</a> • <a href="command-line-options.html#level-colors">‑level‑colors</a> • <a href="command-line-options.html#limit">‑limit</a> • <a href="command-line-options.html#linear-stretch">‑linear‑stretch</a> • <a href="command-line-options.html#linewidth">‑linewidth</a> • <a href="command-line-options.html#liquid-rescale">‑liquid‑rescale</a> • <a href="command-line-options.html#list">‑list</a> • <a href="command-line-options.html#log">‑log</a> • <a href="command-line-options.html#loop">‑loop</a> • <a href="command-line-options.html#lowlight-color">‑lowlight‑color</a> • <a href="command-line-options.html#magnify">‑magnify</a> • <a href="command-line-options.html#map">‑map</a> • <a href="command-line-options.html#map_stream_">‑map[stream]</a> • <a href="command-line-options.html#mask">‑mask</a> • <a href="command-line-options.html#mattecolor">‑mattecolor</a> • <a href="command-line-options.html#median">‑median</a> • <a href="command-line-options.html#mean-shift">‑mean‑shift</a> • <a href="command-line-options.html#metric">‑metric</a> • <a href="command-line-options.html#mode">‑mode</a> • <a href="command-line-options.html#modulate">‑modulate</a> • <a href="command-line-options.html#moments">‑moments</a> • <a href="command-line-options.html#monitor">‑monitor</a> • <a href="command-line-options.html#monochrome">‑monochrome</a> • <a href="command-line-options.html#morph">‑morph</a> • <a href="command-line-options.html#morphology">‑morphology</a> • <a href="command-line-options.html#mosaic">‑mosaic</a> • <a href="command-line-options.html#motion-blur">‑motion‑blur</a> • <a href="command-line-options.html#name">‑name</a> • <a href="command-line-options.html#negate">‑negate</a> • <a href="command-line-options.html#noise">‑noise</a> • <a href="command-line-options.html#normalize">‑normalize</a> • <a href="command-line-options.html#opaque">‑opaque</a> • <a href="command-line-options.html#ordered-dither">‑ordered‑dither</a> • <a href="command-line-options.html#orient">‑orient</a> • <a href="command-line-options.html#page">‑page</a> • <a href="command-line-options.html#paint">‑paint</a> • <a href="command-line-options.html#path">‑path</a> • <a href="command-line-options.html#pause_animate_">‑pause[animate]</a> • <a href="command-line-options.html#pause_import_">‑pause[import]</a> • <a href="command-line-options.html#perceptible">‑perceptible</a> • <a href="command-line-options.html#ping">‑ping</a> • <a href="command-line-options.html#pointsize">‑pointsize</a> • <a href="command-line-options.html#polaroid">‑polaroid</a> • <a href="command-line-options.html#poly">‑poly</a> • <a href="command-line-options.html#posterize">‑posterize</a> • <a href="command-line-options.html#precision">‑precision</a> • <a href="command-line-options.html#preview">‑preview</a> • <a href="command-line-options.html#print">‑print</a> • <a href="command-line-options.html#process">‑process</a> • <a href="command-line-options.html#profile">‑profile</a> • <a href="command-line-options.html#quality">‑quality</a> • <a href="command-line-options.html#quantize">‑quantize</a> • <a href="command-line-options.html#quiet">‑quiet</a> • <a href="command-line-options.html#radial-blur">‑radial‑blur</a> • <a href="command-line-options.html#raise">‑raise</a> • <a href="command-line-options.html#random-threshold">‑random‑threshold</a> • <a href="command-line-options.html#red-primary">‑red‑primary</a> • <a href="command-line-options.html#regard-warnings">‑regard‑warnings</a> • <a href="command-line-options.html#region">‑region</a> • <a href="command-line-options.html#remap">‑remap</a> • <a href="command-line-options.html#remote">‑remote</a> • <a href="command-line-options.html#render">‑render</a> • <a href="command-line-options.html#repage">‑repage</a> • <a href="command-line-options.html#resample">‑resample</a> • <a href="command-line-options.html#resize">‑resize</a> • <a href="command-line-options.html#respect-parentheses">‑respect‑parentheses</a> • <a href="command-line-options.html#reverse">‑reverse</a> • <a href="command-line-options.html#roll">‑roll</a> • <a href="command-line-options.html#rotate">‑rotate</a> • <a href="command-line-options.html#sample">‑sample</a> • <a href="command-line-options.html#sampling-factor">‑sampling‑factor</a> • <a href="command-line-options.html#scale">‑scale</a> • <a href="command-line-options.html#scene">‑scene</a> • <a href="command-line-options.html#screen">‑screen</a> • <a href="command-line-options.html#seed">‑seed</a> • <a href="command-line-options.html#segment">‑segment</a> • <a href="command-line-options.html#selective-blur">‑selective‑blur</a> • <a href="command-line-options.html#separate">‑separate</a> • <a href="command-line-options.html#sepia-tone">‑sepia‑tone</a> • <a href="command-line-options.html#set">‑set</a> • <a href="command-line-options.html#shade">‑shade</a> • <a href="command-line-options.html#shadow">‑shadow</a> • <a href="command-line-options.html#shared-memory">‑shared‑memory</a> • <a href="command-line-options.html#sharpen">‑sharpen</a> • <a href="command-line-options.html#shave">‑shave</a> • <a href="command-line-options.html#shear">‑shear</a> • <a href="command-line-options.html#sigmoidal-contrast">‑sigmoidal‑contrast</a> • <a href="command-line-options.html#silent">‑silent</a> • <a href="command-line-options.html#similarity-threshold">‑similarity‑threshold</a> • <a href="command-line-options.html#size">‑size</a> • <a href="command-line-options.html#sketch">‑sketch</a> • <a href="command-line-options.html#smush">‑smush</a> • <a href="command-line-options.html#snaps">‑snaps</a> • <a href="command-line-options.html#solarize">‑solarize</a> • <a href="command-line-options.html#sparse-color">‑sparse‑color</a> • <a href="command-line-options.html#splice">‑splice</a> • <a href="command-line-options.html#spread">‑spread</a> • <a href="command-line-options.html#statistic">‑statistic</a> • <a href="command-line-options.html#stegano">‑stegano</a> • <a href="command-line-options.html#stereo">‑stereo</a> • <a href="command-line-options.html#storage-type">‑storage‑type</a> • <a href="command-line-options.html#stretch">‑stretch</a> • <a href="command-line-options.html#strip">‑strip</a> • <a href="command-line-options.html#stroke">‑stroke</a> • <a href="command-line-options.html#strokewidth">‑strokewidth</a> • <a href="command-line-options.html#style">‑style</a> • <a href="command-line-options.html#subimage-search">‑subimage‑search</a> • <a href="command-line-options.html#swap">‑swap</a> • <a href="command-line-options.html#swirl">‑swirl</a> • <a href="command-line-options.html#synchronize">‑synchronize</a> • <a href="command-line-options.html#taint">‑taint</a> • <a href="command-line-options.html#text-font">‑text‑font</a> • <a href="command-line-options.html#texture">‑texture</a> • <a href="command-line-options.html#threshold">‑threshold</a> • <a href="command-line-options.html#thumbnail">‑thumbnail</a> • <a href="command-line-options.html#tile">‑tile</a> • <a href="command-line-options.html#tile-offset">‑tile‑offset</a> • <a href="command-line-options.html#tint">‑tint</a> • <a href="command-line-options.html#title">‑title</a> • <a href="command-line-options.html#transform">‑transform</a> • <a href="command-line-options.html#transparent">‑transparent</a> • <a href="command-line-options.html#transparent-color">‑transparent‑color</a> • <a href="command-line-options.html#transpose">‑transpose</a> • <a href="command-line-options.html#transverse">‑transverse</a> • <a href="command-line-options.html#treedepth">‑treedepth</a> • <a href="command-line-options.html#trim">‑trim</a> • <a href="command-line-options.html#type">‑type</a> • <a href="command-line-options.html#undercolor">‑undercolor</a> • <a href="command-line-options.html#unique-colors">‑unique‑colors</a> • <a href="command-line-options.html#units">‑units</a> • <a href="command-line-options.html#unsharp">‑unsharp</a> • <a href="command-line-options.html#update">‑update</a> • <a href="command-line-options.html#verbose">‑verbose</a> • <a href="command-line-options.html#version">‑version</a> • <a href="command-line-options.html#view">‑view</a> • <a href="command-line-options.html#vignette">‑vignette</a> • <a href="command-line-options.html#virtual-pixel">‑virtual‑pixel</a> • <a href="command-line-options.html#visual">‑visual</a> • <a href="command-line-options.html#watermark">‑watermark</a> • <a href="command-line-options.html#wave">‑wave</a> • <a href="command-line-options.html#weight">‑weight</a> • <a href="command-line-options.html#white-point">‑white‑point</a> • <a href="command-line-options.html#white-threshold">‑white‑threshold</a> • <a href="command-line-options.html#window">‑window</a> • <a href="command-line-options.html#window-group">‑window‑group</a> • <a href="command-line-options.html#write">‑write</a> </p>
48
49<p class="lead magick-description">Below is list of command-line options recognized by the ImageMagick <a href="command-line-tools.html">command-line tools</a>. If you want a description of a particular option, click on the option name in the navigation bar above and you will go right to it. Unless otherwise noted, each option is recognized by the commands: <a href="convert.html">convert</a> and <a href="mogrify.html">mogrify</a>.</p>
50
51<div style="margin: auto;">
52 <h3 class="magick-header"><a id="adaptive-blur"></a>-adaptive-blur <var>radius</var>[x<var>sigma</var>]</h3>
53</div>
54
55<p class="magick-description">Adaptively blur pixels, with decreasing effect near edges.</p>
56
57<p>A Gaussian operator of the given radius and standard deviation (<var>sigma</var>) is used. If <var>sigma</var> is not given it
58defaults to 1.</p>
59
60<div style="margin: auto;">
61 <h3 class="magick-header"><a id="adaptive-resize"></a>-adaptive-resize <var>geometry</var></h3>
62</div>
63
64<p class="magick-description">Resize the image using data-dependent triangulation.</p>
65
66<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <a href="command-line-options.html#adaptive-resize">-adaptive-resize</a>
67option defaults to data-dependent triangulation. Use the <a href="command-line-options.html#filter">-filter</a> to choose a different resampling algorithm.
68Offsets, if present in the geometry string, are ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
69
70<div style="margin: auto;">
71 <h3 class="magick-header"><a id="adaptive-sharpen"></a>-adaptive-sharpen <var>radius</var>[x<var>sigma</var>]</h3>
72</div>
73
74<p class="magick-description">Adaptively sharpen pixels, with increasing effect near edges.</p>
75
76<p>A Gaussian operator of the given radius and standard deviation
77(<var>sigma</var>) is used. If <var>sigma</var> is not given it
78defaults to 1.</p>
79
80<div style="margin: auto;">
81 <h3 class="magick-header"><a id="adjoin"></a>-adjoin</h3>
82</div>
83
84<p class="magick-description">Join images into a single multi-image file.</p>
85
86<p>This option is enabled by default. An attempt is made to save all images of
87an image sequence into the given output file. However, some formats, such as
88JPEG and PNG, do not support more than one image per file, and in that case
89ImageMagick is forced to write each image as a separate file. As such, if
90more than one image needs to be written, the filename given is modified by
91adding a <a href="command-line-options.html#scene">-scene</a> number before the suffix, in order to
92make distinct names for each image. </p>
93
94<p>Use <a href="command-line-options.html#adjoin">+adjoin</a> to force each image to be written to
95separate files, whether or not the file format allows multiple images per file
96(for example, GIF, MIFF, and TIFF). </p>
97
98<p>Including a C-style integer format string in the output filename will
99automagically enable <a href="command-line-options.html#adjoin">+adjoin</a> and are used to specify
100where the <a href="command-line-options.html#scene">-scene</a> number is placed in the filenames. These
101strings, such as '<code>%d</code>' or '<code>%03d</code>', are familiar to those
102who have used the standard <code>printf()</code>' C-library function. As an
103example, the command</p>
104
105<pre>
106convert logo: rose: -morph 15 my%02dmorph.jpg
107</pre>
108
109<p>will create a sequence of 17 images (the two given plus 15 more created by
110<a href="command-line-options.html#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg,
111my02morph.jpg, ..., my16morph.jpg. </p>
112
113<p>In summary, ImageMagick tries to write all images to one file, but will
114save to multiple files, if any of the following conditions exist...</p>
115<ol>
116<li>the output image's file format does not allow multi-image files,</li>
117<li>the <a href="command-line-options.html#adjoin">+adjoin</a> option is given, or</li>
118<li>a printf() integer format string (eg: "%d") is present in the output
119 filename.</li>
120</ol>
121
122
123<div style="margin: auto;">
124 <h3 class="magick-header"><a id="affine"></a>-affine
125 <var>s<sub>x</sub></var>,<var>r<sub>x</sub></var>,<var>r<sub>y</sub></var>,<var>s<sub>y</sub></var>[,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>]</h3>
126</div>
127
128<p class="magick-description">Set the drawing transformation matrix for combined rotating and scaling.</p>
129
130<p>This option sets a transformation matrix, for use by subsequent <a href="command-line-options.html#draw">-draw</a> or <a href="command-line-options.html#transform">-transform</a> options. </p>
131
132<p>The matrix entries are entered as comma-separated numeric values either in
133quotes or without spaces. </p>
134
135<p>Internally, the transformation matrix has 3x3 elements, but three of them
136are omitted from the input because they are constant. The new (transformed)
137coordinates (<var>x'</var>, <var>y'</var>) of a pixel at
138position (<var>x</var>, <var>y</var>) in the original
139image are calculated using the following matrix equation.</p>
140
141<p class="text-center"><img class="img-thumbnail" alt="affine transformation" src="../images/affine.png"> </p>
142
143<p> The size of the resulting image is that of the smallest rectangle that
144contains the transformed source image. The parameters
145<var>t<sub>x</sub></var> and <var>t<sub>y</sub></var>
146subsequently shift the image pixels so that those that are moved out of the
147image area are cut off.</p>
148
149<p>The transformation matrix complies with the left-handed pixel coordinate
150system: positive <var>x</var> and <var>y</var> directions
151are rightward and downward, resp.; positive rotation is clockwise.</p>
152
153<p> If the translation coefficients <var>t<sub>x</sub></var> and
154<var>t<sub>y</sub></var> are omitted they default to 0,0. Therefore,
155four parameters suffice for rotation and scaling without translation.</p>
156
157<p>Scaling by the factors <var>s<sub>x</sub></var> and
158<var>s<sub>y</sub></var> in the <var>x</var> and <var>y</var> directions,
159respectively, is accomplished with the following.</p>
160
161<p>See <a href="command-line-options.html#transform">-transform</a>, and the <a href="command-line-options.html#distort">-distort</a> method '<code>Affineprojection</code> for more
162information </p>
163
164
165<pre>
166-affine <var>s<sub>x</sub></var>,0,0,<var>s<sub>y</sub></var>
167</pre>
168
169<p>Translation by a displacement (<var>t<sub>x</sub></var>, <var>t<sub>y</sub></var>) is accomplished like so:</p>
170
171<pre>
172-affine 1,0,0,1,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>
173</pre>
174
175<p>Rotate clockwise about the origin (the upper left-hand corner) by an angle
176<var>a</var> by letting <var>c</var> = cos(<var>a</var>), <var>s</var>
177= sin(<var>a</var>), and using the following.</p>
178
179<pre>
180-affine <var>c</var>,<var>s</var>,-<var>s</var>,<var>c</var>
181</pre>
182
183<p>The cumulative effect of a sequence of <a href="command-line-options.html#affine">-affine</a>
184transformations can be accomplished by instead by a single <a href="command-line-options.html#affine">-affine</a> operation using the matrix equal to the product of the matrices
185of the individual transformations.</p>
186
187<p>An attempt is made to detect near-singular transformation matrices. If the
188matrix determinant has a sufficiently small absolute value it is rejected.</p>
189
190<div style="margin: auto;">
191 <h3 class="magick-header"><a id="alpha"></a>-alpha <var>type</var></h3>
192</div>
193
194<p class="magick-description">Gives control of the alpha/matte channel of an image.</p>
195
196<p>Used to set a flag on an image indicating whether or not to use existing alpha
197channel data, to create an alpha channel, or to perform other operations on the alpha channel. Choose the argument <var>type</var> from the list below.</p>
198
199<dl class="dl-horizontal">
200 <dt>Activate</dt>
201 <dd>
202 Enable the image's transparency channel. Note normally Set
203 should be used instead of this, unless you specifically need to
204 preserve existing (but specifically turned Off) transparency
205 channel. </dd>
206
207 <dt>Associate</dt>
208 <dd>
209 associate the alpha channel with the image.</dd>
210
211 <dt>Deactivate</dt>
212 <dd>
213 Disables the image's transparency channel. Does not delete or change the
214 existing data, just turns off the use of that data.</dd>
215
216 <dt>Disassociate</dt>
217 <dd>
218 disassociate the alpha channel from the image.</dd>
219
220 <dt>Set</dt>
221 <dd>
222 Activates the alpha/matte channel. If it was previously turned off
223 then it also resets the channel to opaque. If the image already had
224 the alpha channel turned on, it will have no effect.</dd>
225
226 <dt>Opaque</dt>
227 <dd>
228 Enables the alpha/matte channel and forces it to be fully opaque.
229 </dd>
230
231 <dt>Transparent</dt>
232 <dd>
233 Activates the alpha/matte channel and forces it to be fully
234 transparent. This effectively creates a fully transparent image the
235 same size as the original and with all its original RGB data still
236 intact, but fully transparent. </dd>
237
238 <dt>Extract</dt>
239 <dd>
240 Copies the alpha channel values into all the color channels and turns
241 'Off' the the image's transparency, so as to generate
242 a gray-scale mask of the image's shape. The alpha channel data is left
243 intact just deactivated. This is the inverse of 'Copy'.
244 </dd>
245
246 <dt>Copy</dt>
247 <dd>
248 Turns 'On' the alpha/matte channel, then copies the
249 gray-scale intensity of the image, into the alpha channel, converting
250 a gray-scale mask into a transparent shaped mask ready to be colored
251 appropriately. The color channels are not modified. </dd>
252
253 <dt>Shape</dt>
254 <dd>
255 As per 'Copy' but also colors the resulting shape mask with
256 the current background color. That is the RGB color channels is
257 replaced, with appropriate alpha shape.
258 </dd>
259
260 <dt>Remove</dt>
261 <dd>
262 Composite the image over the background color.
263 </dd>
264
265 <dt>Background</dt>
266 <dd>
267 Set any fully-transparent pixel to the background color, while leaving
268 it fully-transparent. This can make some image file formats, such as
269 PNG, smaller as the RGB values of transparent pixels are more uniform,
270 and thus can compress better.
271 </dd>
272</dl>
273
274<p>Note that while the obsolete <code>+matte</code> operation was the
275same as "<code><a href="command-line-options.html#alpha">-alpha</a> Off</code>", the <code>
276&gt;-matte</code> operation was the same as "<code><a href="command-line-options.html#alpha">-alpha</a>
277Set</code>" and not "<code><a href="command-line-options.html#alpha">-alpha</a> On</code>". </p>
278
279
280<div style="margin: auto;">
281 <h3 class="magick-header"><a id="annotate"></a>
282 -annotate <var>degrees</var> <var>text</var><br>
283 -annotate <var>Xdegrees</var>x<var>Ydegrees</var> <var>text</var><br> -annotate <var>Xdegrees</var>x<var>Ydegrees</var> {+-}<var>t<sub>x</sub></var>{+-}<var>t<sub>y</sub></var> <var>text</var><br> -annotate {+-}<var>t<sub>x</sub></var>{+-}<var>t<sub>y</sub></var> <var>text</var></h3>
284</div>
285
286<p class="magick-description">Annotate an image with text</p>
287
288<p>This is a convenience for annotating an image with text. For more precise
289control over text annotations, use <a href="command-line-options.html#draw">-draw</a>.</p>
290
291
292<p>The values <var>Xdegrees</var> and <var>Ydegrees</var>
293control the shears applied to the text, while <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are offsets that give the location of the text relative any <a href="command-line-options.html#gravity">-gravity</a> setting and defaults to the upper left corner of the image.</p>
294
295<p>Using <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>
296or <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>x<var>degrees</var> produces an unsheared rotation of the text. The
297direction of the rotation is positive, which means a clockwise rotation if <var>degrees</var> is positive. (This conforms to the usual mathematical
298convention once it is realized that the positive <var>y</var>–direction is
299conventionally considered to be <var>downward</var> for images.)</p>
300
301<p>The new (transformed) coordinates (<var>x'</var>, <var>y'</var>) of a pixel at position (<var>x</var>, <var>y</var>) in the image are calculated using the following matrix
302equation.</p>
303
304<p class="text-center"><img class="img-thumbnail" alt="annotate transformation" src="../images/annotate.png"></p>
305
306<p>If <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are omitted, they default to 0. This makes the
307bottom-left of the text becomes the upper-left corner of the image, which is
308probably undesirable. Adding a <a href="command-line-options.html#gravity">-gravity</a> option in this
309case leads to nice results.</p>
310
311<p>Text is any UTF-8 encoded character sequence. If <var>text</var>
312is of the form '@mytext.txt', the text is read from the file
313<code>mytext.txt</code>. Text in a file is taken literally; no embedded
314formatting characters are recognized.</p>
315
316<div style="margin: auto;">
317 <h3 class="magick-header"><a id="antialias"></a>-antialias</h3>
318</div>
319
320<p class="magick-description">Enable/Disable of the rendering of anti-aliasing pixels when drawing fonts and lines.</p>
321
322<p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
323drawn. Use <a href="command-line-options.html#antialias">+antialias</a> to disable the addition of
324antialiasing edge pixels. This will then reduce the number of colors added to
325an image to just the colors being directly drawn. That is, no mixed colors
326are added when drawing such objects. </p>
327
328<div style="margin: auto;">
329 <h3 class="magick-header"><a id="append"></a>-append</h3>
330</div>
331
332<p class="magick-description">Join current images vertically or horizontally.</p>
333
334<p>This option creates a single longer image, by joining all the current
335images in sequence top-to-bottom. Use <a href="command-line-options.html#append">+append</a> to
336stack images left-to-right. </p>
337
338<p>If they are not of the same width, narrower images are padded with the
339current <a href="command-line-options.html#background">-background</a> color setting, and their
340position relative to each other can be controlled by the current <a href="command-line-options.html#gravity">-gravity</a> setting. </p>
341
342
343<div style="margin: auto;">
344 <h3 class="magick-header"><a id="attenuate"></a>-attenuate <var>value</var></h3>
345</div>
346
347<p class="magick-description">Lessen (or intensify) when adding noise to an image.</p>
348
349<p>If unset the value is equivalent to 1.0, or a maximum noise addition</p>
350
351<div style="margin: auto;">
352 <h3 class="magick-header"><a id="authenticate"></a>-authenticate <var>password</var></h3>
353</div>
354
355<p class="magick-description">Decrypt a PDF with a password.</p>
356
357<p>Use this option to supply a <var>password</var> for decrypting
358a PDF that has been encrypted using Microsoft Crypto API (MSC API). The
359encrypting using the MSC API is not supported.</p>
360
361<p>For a different encryption method, see <a href="command-line-options.html#encipher">-encipher</a>
362and <a href="command-line-options.html#decipher">-decipher</a>. </p>
363
364
365<div style="margin: auto;">
366 <h3 class="magick-header"><a id="auto-gamma"></a>-auto-gamma</h3>
367</div>
368
369<p class="magick-description">Automagically adjust gamma level of image.</p>
370
371<p>This calculates the mean values of an image, then applies a calculated <a href="command-line-options.html#gamma">-gamma</a> adjustment so that is the mean color exists in the
372image it will get a have a value of 50%. </p>
373
374<p>This means that any solid 'gray' image becomes 50% gray. </p>
375
376<p>This works well for real-life images with little or no extreme dark and
377light areas, but tend to fail for images with large amounts of bright sky or
378dark shadows. It also does not work well for diagrams or cartoon like images.
379</p>
380
381<p>It uses the <a href="command-line-options.html#channel">-channel</a> setting, (including the
382'<var>sync</var>' flag for channel synchronization), to determine which color
383values is used and modified. As the default <a href="command-line-options.html#channel">-channel</a> setting is '<var>RGB,sync</var>', channels are modified
384together by the same gamma value, preserving colors. </p>
385
386
387
388<div style="margin: auto;">
389 <h3 class="magick-header"><a id="auto-level"></a>-auto-level</h3>
390</div>
391
392<p class="magick-description">Automagically adjust color levels of image.</p>
393
394<p>This is a 'perfect' image normalization operator. It finds the exact
395minimum and maximum color values in the image and then applies a <a href="command-line-options.html#level">-level</a> operator to stretch the values to the full range of
396values. </p>
397
398<p>The operator is not typically used for real-life images, image scans, or
399JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
400for the <a href="command-line-options.html#level">-level</a> operation. On the other hand it is the
401right operator to use for color stretching gradient images being used to
402generate Color lookup tables, distortion maps, or other 'mathematically'
403defined images. </p>
404
405<p>The operator is very similar to the <a href="command-line-options.html#normalize">-normalize</a>, <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>, and <a href="command-line-options.html#linear-stretch">-linear-stretch</a> operators, but without 'histogram binning' or 'clipping'
406problems that these operators may have. That is <a href="command-line-options.html#auto-level">-auto-level</a> is the perfect or ideal version these operators. </p>
407
408<p>It uses the <a href="command-line-options.html#channel">-channel</a> setting, (including the
409special '<var>sync</var>' flag for channel synchronization), to determine
410which color values are used and modified. As the default <a href="command-line-options.html#channel">+channel</a> setting is '<var>RGB,sync</var>', the
411'<var>sync</var>' ensures that the color channels will are modified
412together by the same gamma value, preserving colors, and ignoring
413transparency. </p>
414
415
416<div style="margin: auto;">
417 <h3 class="magick-header"><a id="auto-orient"></a>-auto-orient</h3>
418</div>
419
420<p class="magick-description">adjusts an image so that its orientation is suitable for viewing (i.e. top-left orientation).</p>
421
422<p>This operator reads and resets the EXIF image profile setting 'Orientation'
423and then performs the appropriate 90 degree rotation on the image to orient
424the image, for correct viewing. </p>
425
426<p>This EXIF profile setting is usually set using a gravity sensor in digital
427camera, however photos taken directly downward or upward may not have an
428appropriate value. Also images that have been orientation 'corrected' without
429reseting this setting, may be 'corrected' again resulting in a incorrect
430result. If the EXIF profile was previously stripped, the <a href="command-line-options.html#auto-orient">-auto-orient</a> operator will do nothing. </p>
431
432
433<div style="margin: auto;">
434 <h3 class="magick-header"><a id="average"></a>-average</h3>
435</div>
436
437<p class="magick-description">Average a set of images.</p>
438
439<p>An error results if the images are not identically sized.</p>
440
441
442<div style="margin: auto;">
443 <h3 class="magick-header"><a id="backdrop"></a>-backdrop</h3>
444</div>
445
446<p class="magick-description">Display the image centered on a backdrop.</p>
447
448<p>This backdrop covers the entire workstation screen and is useful for hiding
449other X window activity while viewing the image. The color of the backdrop is
450specified as the background color. The color is specified using the format
451described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
452
453<div style="margin: auto;">
454 <h3 class="magick-header"><a id="background"></a>-background <var>color</var></h3>
455</div>
456
457<p class="magick-description">Set the background color.</p>
458
459<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option. The default background color (if none is
460specified or found in the image) is white.</p>
461
462<div style="margin: auto;">
463 <h3 class="magick-header"><a id="bench"></a>-bench <var>iterations</var></h3>
464</div>
465
466<p class="magick-description">Measure performance.</p>
467
468<p>Repeat the entire command for the given number of <var>iterations</var> and report the user-time and elapsed time. For instance,
469consider the following command and its output. Modify the benchmark with the
470-duration to run the benchmark for a fixed number of seconds and -concurrent
471to run the benchmark in parallel (requires the OpenMP feature).</p>
472
473<pre>
474-&gt; convert logo: -resize 1000% -bench 5 logo.png
475Performance[4]: 5i 0.875657ips 6.880u 0:05.710
476</pre>
477
478<p>In this example, 5 iterations were completed at 0.875657 iterations per
479second, using 4 threads and 6.88 seconds of the user's allotted time, for
480a total elapsed time of 5.71 seconds.</p>
481
482<div style="margin: auto;">
483 <h3 class="magick-header"><a id="bias"></a>-bias <var>value</var>{<var>%</var>}</h3>
484</div>
485
486<p class="magick-description">Add bias when convolving an image.</p>
487
488<p>This option shifts the output of <a href="command-line-options.html#convolve">‑convolve</a> so that
489positive and negative results are relative to the specified bias value. </p>
490
491<p>This is important for non-HDRI compilations of ImageMagick when dealing
492with convolutions that contain negative as well as positive values. This is
493especially the case with convolutions involving high pass filters or edge
494detection. Without an output bias, the negative values are clipped at
495zero.</p>
496
497<p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
498negative results without clipping to the color value range
499(0..QuantumRange).</p>
500
501<p>See the discussion on HDRI implementations of ImageMagick on the page <a href="high-dynamic-range.html">High Dynamic-Range Images</a>. For more
502about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
503<a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
504entry. </p>
505
506<div style="margin: auto;">
507 <h3 class="magick-header"><a id="black-point-compensation"></a>-black-point-compensation</h3>
508</div>
509
510<p class="magick-description">Use black point compensation.</p>
511
512<div style="margin: auto;">
513 <h3 class="magick-header"><a id="black-threshold"></a>-black-threshold <var>value</var>{<var>%</var>}</h3>
514</div>
515
516<p class="magick-description">Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</p>
517
518<p> The threshold value can be given as a percentage or as an absolute integer
519value within [0, <var>QuantumRange</var>] corresponding to the
520desired <a href="command-line-options.html#channel">‑channel</a> value. See <a href="command-line-options.html#threshold">‑threshold</a>for more details on thresholds and resulting values. </p>
521
522
523<div style="margin: auto;">
524 <h3 class="magick-header"><a id="blend"></a>-blend <var>geometry</var></h3>
525</div>
526
527<p class="magick-description">blend an image into another by the given absolute value or percent.</p>
528
529<p>Blend will average the images together ('plus') according to the
530percentages given and each pixels transparency. If only a single percentage
531value is given it sets the weight of the composite or 'source' image, while
532the background image is weighted by the exact opposite amount. That is a
533<code>-blend 30%</code> merges 30% of the 'source' image with 70% of the
534'destination' image. Thus it is equivalent to <code>-blend 30x70%</code>.</p>
535
536
537<div style="margin: auto;">
538 <h3 class="magick-header"><a id="blue-primary"></a>-blue-primary <var>x</var>,<var>y</var></h3>
539</div>
540
541<p class="magick-description">Set the blue chromaticity primary point.</p>
542
543<div style="margin: auto;">
544 <h3 class="magick-header"><a id="blue-shift"></a>-blue-shift <var>factor</var></h3>
545</div>
546
547<p class="magick-description">simulate a scene at nighttime in the moonlight. Start with a factor of 1.5</p>
548
549<div style="margin: auto;">
550
551<div style="margin: auto;">
552 <h3 class="magick-header"><a id="blur"></a>-blur <var>radius</var><br>-blur <var>radius</var>x<var>sigma</var></h3>
553</div>
554
555<p class="magick-description">Reduce image noise and reduce detail levels.</p>
556
557<p>Convolve the image with a Gaussian or normal distribution using the given
558<var>Sigma</var> value. The formula is:</p>
559
560<p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"></p>
561
562<p>The <var>Sigma</var> value is the important argument, and
563determines the actual amount of blurring that will take place. </p>
564
565<p>The <var>Radius</var> is only used to determine the size of the
566array which will hold the calculated Gaussian distribution. It should be an
567integer. If not given, or set to zero, IM will calculate the largest possible
568radius that will provide meaningful results for the Gaussian distribution.
569</p>
570
571<p>The larger the <var>Radius</var> the slower the
572operation is. However too small a <var>Radius</var>, and sever
573aliasing effects may result. As a guideline, <var>Radius</var>
574should be at least twice the <var>Sigma</var> value, though three
575times will produce a more accurate result. </p>
576
577<p>This option differs from <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a> simply
578by taking advantage of the separability properties of the distribution. Here
579we apply a single-dimensional Gaussian matrix in the horizontal direction,
580then repeat the process in the vertical direction.</p>
581
582<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
583pixels which are outside the image proper are blurred into the final result.
584</p>
585
586
587<div style="margin: auto;">
588 <h3 class="magick-header">-blur <var>Width</var>[x<var>Height</var>[+<var>Angle</var>]]</h3>
589</div>
590
591<p class="magick-description">Variably blur an image according to the overlay mapping.</p>
592
593<p>Each pixel in the overlaid region is replaced with an Elliptical Weighted
594Average (EWA) of the source image, scaled according to the grayscale
595mapping. </p>
596
597<p>The ellipse is weighted with sigma set to the given <var>Width</var> and <var>Height</var>. The <var>Height</var>
598defaults to the <var>Width</var> for a normal circular Gaussian
599weighting. The <var>Angle</var> will rotate the ellipse from
600horizontal clock-wise. </p>
601
602<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
603pixels which are outside the image proper are blurred into the final result.
604</p>
605
606
607<div style="margin: auto;">
608 <h3 class="magick-header"><a id="border"></a>-border <var>geometry</var></h3>
609</div>
610
611<p class="magick-description">Surround the image with a border of color. </p>
612
613<p>Set the width and height using the <var>size</var> portion of the
614<var>geometry</var> argument. See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets are
615ignored. </p>
616
617<p>As of IM 6.7.8-8, the <var>geometry</var> arguments behave as follows:</p>
618
619<dl class="dl-horizontal">
620<dt><var>value</var></dt>
621<dd>value is added to both left/right and top/bottom</dd>
622<dt><var>value-x</var><kbd>x</kbd></dt>
623<dd>value-x is added only to left/right and top/bottom are unchanged</dd>
624<dt><kbd>x</kbd><var>value-y</var></dt>
625<dd>value-y is added only to top/bottom and left/right are unchanged</dd>
626<dt><var>value-x</var><kbd>x</kbd><var>value-y</var></dt>
627<dd>value-x is added to left/right and value-y added to top/bottom</dd>
628<dt><var>value-x</var><kbd>x</kbd>0</dt>
629<dd>value-x is added only to left/right and top/bottom are unchanged</dd>
630<dt>0<kbd>x</kbd><var>value-y</var></dt>
631<dd>value-y is added only to top/bottom and left/right are unchanged</dd>
632<dt><var>value</var>%</dt>
633<dd>value % of width is added to left/right and value % of height is added to top/bottom</dd>
634<dt><var>value-x</var><kbd>x</kbd>%</dt>
635<dd>value-x % of width is added to left/right and to top/bottom</dd>
636<dt>x<var>value-y</var>%</dt>
637<dd>value-y % of height is added to top/bottom and to left/right</dd>
638<dt><var>value-x</var>%<kbd>x</kbd><var>value-y</var>%</dt>
639<dd>value-x % of width is added to left/right and value-y % of height is added to top/bottom</dd>
640<dt><var>value-x</var>%<kbd>x</kbd>0%</dt>
641<dd>value-x % of width is added to left/right and top/bottom are unchanged</dd>
642<dt>0%<kbd>x</kbd><var>value-y</var>%</dt>
643<dd>value-y % of height is added to top/bottom and left/right are unchanged</dd>
644</dl>
645
646<p>Set the border color by preceding with the <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
647
648<p>The <a href="command-line-options.html#border">-border</a> operation is affected by the current <a href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
649'<code>Over</code>' composition method. It generates an image of the appropriate
650size colors by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> before
651overlaying the original image in the center of this net image. This means that
652with the default compose method of '<code>Over</code>' any transparent parts may
653be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
654<p>See also the <a href="command-line-options.html#frame">-frame</a> option, which has more
655functionality.</p>
656
657<div style="margin: auto;">
658 <h3 class="magick-header"><a id="bordercolor"></a>-bordercolor <var>color</var></h3>
659</div>
660
661<p class="magick-description">Set the border color.</p>
662
663<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
664
665<p>The default border color is <code>#DFDFDF</code>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
666
667<div style="margin: auto;">
668 <h3 class="magick-header"><a id="borderwidth"></a>-borderwidth <var>geometry</var> </h3>
669</div>
670
671<p class="magick-description">Set the border width.</p>
672
673<div style="margin: auto;">
674 <h3 class="magick-header"><a id="brightness-contrast"></a>-brightness-contrast <var>brightness</var><br>-brightness-contrast <var>brightness</var>{x<var>contrast</var>}{<var>%</var>}}</h3>
675</div>
676
677<p class="magick-description">Adjust the brightness and/or contrast of the image.</p>
678
679<p>Brightness and Contrast values apply changes to the input image. They are
680not absolute settings. A brightness or contrast value of zero means no change.
681The range of values is -100 to +100 on each. Positive values increase the
682brightness or contrast and negative values decrease the brightness or contrast.
683To control only contrast, set the brightness=0. To control only brightness,
684set contrast=0 or just leave it off.</p>
685
686<p>You may also use <a href="command-line-options.html#fill">-channel</a> to control which channels to
687apply the brightness and/or contrast change. The default is to apply the same
688transformation to all channels.</p>
689
690<p>Brightness and Contrast arguments are converted to offset and slope of a
691linear transform and applied
692using <a href="command-line-options.html#fill">-function polynomial "slope,offset"</a>.</p>
693
694<p>The slope varies from 0 at contrast=-100 to almost vertical at
695contrast=+100. For brightness=0 and contrast=-100, the result are totally
696midgray. For brightness=0 and contrast=+100, the result will approach but
697not quite reach a threshold at midgray; that is the linear transformation
698is a very steep vertical line at mid gray.</p>
699
700<p>Negative slopes, i.e. negating the image, are not possible with this
701function. All achievable slopes are zero or positive.</p>
702
703<p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
704at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
705totally white. Similarly, when contrast=0 and brightness=-100, the result is
706totally black.</p>
707
708<p>As the range of values for the arguments are -100 to +100, adding the '%'
709symbol is no different than leaving it off.</p>
710
711<div style="margin: auto;">
712 <h3 class="magick-header"><a id="cache"></a>-cache <var>threshold</var></h3>
713</div>
714
715<p class="magick-description">(This option has been replaced by the <a href="command-line-options.html#limit">-limit</a> option).</p>
716
717<div style="margin: auto;">
718 <h3 class="magick-header"><a id="canny"></a>-canny <var>radius</var><br>-canny <var>radius</var>x<var>sigma</var>{<var>+lower-percent</var>}{<var>+upper-percent</var>}</h3>
719</div>
720
721<p class="magick-description">Canny edge detector uses a multi-stage algorithm to detect a wide range of edges in the image.</p>
722
723<p>The thresholds range from 0 to 100% (e.g. -canny 0x1+10%+30%) with {<var>+lower-percent</var>} &lt; {<var>+upper-percent</var>}. If {<var>+upper-percent</var>} is increased but {<var>+lower-percent</var>} remains the same, lesser edge components will be detected, but their lengths will be the same. If {<var>+lower-percent</var>} is increased but {<var>+upper-percent</var>} is the same, the same number of edge components will be detected but their lengths will be shorter. The default thresholds are shown. The <var>radius</var>x<var>sigma</var> controls a gaussian blur applied to the input image to reduce noise and smooth the edges.</p>
724
725<div style="margin: auto;">
726 <h3 class="magick-header"><a id="caption"></a>-caption <var>string</var></h3>
727</div>
728
729<p class="magick-description">Assign a caption to an image.</p>
730
731<p>This option sets the caption meta-data of an image read in after this
732option has been given. To modify a caption of images already in memory use
733"<code><a href="command-line-options.html#set">-set</a> caption</code>". </p>
734
735<p>The caption can contain special format characters listed in the <a href="escape.html">Format and
736Print Image Properties</a>. These attributes are expanded when the caption
737is finally assigned to the individual images. </p>
738
739<p>If the first character of <var>string</var> is <var>@</var>, the image caption is read from a file titled by the
740remaining characters in the string. Comments read in from a file are literal;
741no embedded formatting characters are recognized.</p>
742
743<p>Caption meta-data is not visible on the image itself. To do that use the
744<a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
745instead.</p>
746
747<p>For example,</p>
748
749<pre>
750-caption "%m:%f %wx%h" bird.miff
751</pre>
752
753<p>produces an image caption of <code>MIFF:bird.miff 512x480</code> (assuming
754that the image <code>bird.miff</code> has a width of 512 and a height of
755480.</p>
756
757
758<div style="margin: auto;">
759 <h3 class="magick-header"><a id="cdl"></a>-cdl <var>filename</var></h3>
760</div>
761
762<p class="magick-description">color correct with a color decision list.</p>
763
764<p>Here is an example color correction collection:</p>
765
766<pre>
767&lt;?xml version="1.0" encoding="UTF-8"?&gt;
768&lt;ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2"&gt;
769 &lt;ColorCorrection id="cc06668"&gt;
770 &lt;SOPNode&gt;
771 &lt;Slope&gt; 0.9 1.2 0.5 &lt;/Slope&gt;
772 &lt;Offset&gt; 0.4 -0.5 0.6 &lt;/Offset&gt;
773 &lt;Power&gt; 1.0 0.8 1.5 &lt;/Power&gt;
774 &lt;/SOPNode&gt;
775 &lt;SATNode&gt;
776 &lt;Saturation&gt; 0.85 &lt;/Saturation&gt;
777 &lt;/SATNode&gt;
778 &lt;/ColorCorrection&gt;
779&lt;/ColorCorrectionCollection&gt;
780</pre>
781
782<div style="margin: auto;">
783 <h3 class="magick-header"><a id="channel"></a>-channel <var>type</var></h3>
784</div>
785
786<p class="magick-description">Specify those image color channels to which subsequent operators are limited.</p>
787
788<p>Choose from: <code>Red</code>, <code>Green</code>, <code>Blue</code>,
789<code>Alpha</code>, <code>Gray</code>, <code>Cyan</code>, <code>Magenta</code>,
790<code>Yellow</code>, <code>Black</code>, <code>Opacity</code>,
791<code>Index</code>, <code>RGB</code>, <code>RGBA</code>, <code>CMYK</code>, or
792<code>CMYKA</code>.</p>
793
794<p>The channels above can also be specified as a comma-separated list or can be
795abbreviated as a concatenation of the letters '<code>R</code>', '<code>G</code>',
796'<code>B</code>', '<code>A</code>', '<code>O</code>', '<code>C</code>',
797'<code>M</code>', '<code>Y</code>', '<code>K</code>'.
798
799For example, to only select the <code>Red</code> and <code>Blue</code> channels
800you can either use </p>
801<pre>
802-channel Red,Blue
803</pre>
804<p>or you can use the short hand form</p>
805<pre>
806-channel RB
807</pre>
808
809<p>All the channels that are present in an image can be specified using the
810special channel type <code>All</code>. Not all operators are 'channel capable',
811but generally any operators that are generally 'grey-scale' image operators,
812will understand this setting. See individual operator documentation. </p>
813
814<br>
815
816<p>On top of the normal channel selection an extra flag can be specified,
817'<code>Sync</code>'. This is turned on by default and if set means that
818operators that understand this flag should perform: cross-channel
819synchronization of the channels. If not specified, then most grey-scale
820operators will apply their image processing operations to each individual
821channel (as specified by the rest of the <a href="command-line-options.html#channel">-channel</a>
822setting) completely independently from each other. </p>
823
824<p>For example for operators such as <a href="command-line-options.html#auto-level">-auto-level</a> and
825<a href="command-line-options.html#auto-gamma">-auto-gamma</a> the color channels are modified
826together in exactly the same way so that colors will remain in-sync. Without
827it being set, then each channel is modified separately and
828independently, which may produce color distortion. </p>
829
830<p>The <a href="command-line-options.html#morphology">-morphology</a> '<code>Convolve</code>' method
831and the <a href="command-line-options.html#compose">-compose</a> mathematical methods, also understands
832the '<code>Sync</code>' flag to modify the behaviour of pixel colors according
833to the alpha channel (if present). That is to say it will modify the image
834processing with the understanding that fully-transparent colors should not
835contribute to the final result. </p>
836
837<p>Basically, by default, operators work with color channels in synchronous, and
838treats transparency as special, unless the <a href="command-line-options.html#channel">-channel</a>
839setting is modified so as to remove the effect of the '<code>Sync</code>' flag.
840How each operator does this depends on that operators current implementation.
841Not all operators understands this flag at this time, but that is changing.
842</p>
843
844<p>To print a complete list of channel types, use <a href="command-line-options.html#list">-list
845channel</a>.</p>
846
847<p>By default, ImageMagick sets <a href="command-line-options.html#channel">-channel</a> to the value
848'<code>RGBK,sync</code>', which specifies that operators act on all color
849channels except the transparency channel, and that all the color channels are
850to be modified in exactly the same way, with an understanding of transparency
851(depending on the operation being applied). The 'plus' form <a href="command-line-options.html#channel">+channel</a> will reset the value back to this default. </p>
852
853<p>Options that are affected by the <a href="command-line-options.html#channel">-channel</a> setting
854include the following.
855
856<a href="command-line-options.html#auto-gamma">-auto-gamma</a>,
857<a href="command-line-options.html#auto-level">-auto-level</a>,
858<a href="command-line-options.html#black-threshold">-black-threshold</a>,
859<a href="command-line-options.html#blur">-blur</a>,
860<a href="command-line-options.html#clamp">-clamp</a>,
861<a href="command-line-options.html#clut">-clut</a>,
862<a href="command-line-options.html#combine">-combine</a>,
863<a href="command-line-options.html#composite">-composite</a> (Mathematical compose methods only),
864<a href="command-line-options.html#convolve">-convolve</a>,
865<a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
866<a href="command-line-options.html#evaluate">-evaluate</a>,
867<a href="command-line-options.html#function">-function</a>,
868<a href="command-line-options.html#fx">-fx</a>,
869<a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>,
870<a href="command-line-options.html#hald-clut">-hald-clut</a>,
871<a href="command-line-options.html#motion-blur">-motion-blur</a>,
872<a href="command-line-options.html#morphology">-morphology</a>,
873<a href="command-line-options.html#negate">-negate</a>,
874<a href="command-line-options.html#normalize">-normalize</a>,
875<a href="command-line-options.html#ordered-dither">-ordered-dither</a>,
876<a href="command-line-options.html#radial-blur">-radial-blur</a>,
877<a href="command-line-options.html#random-threshold">-random-threshold</a>,
878<a href="command-line-options.html#separate">-separate</a>,
879<a href="command-line-options.html#threshold">-threshold</a>, and
880<a href="command-line-options.html#white-threshold">-white-threshold</a>.
881</p>
882
883<p>Warning, some operators behave differently when the <a href="command-line-options.html#channel">+channel</a> default setting is in effect, verses ANY user defined <a href="command-line-options.html#channel">-channel</a> setting (including the equivalent of the
884default). These operators have yet to be made to understand the newer 'Sync'
885flag. </p>
886
887<p>For example <a href="command-line-options.html#threshold">-threshold</a> will by default gray-scale
888the image before thresholding, if no <a href="command-line-options.html#channel">-channel</a> setting
889has been defined. This is not 'Sync flag controlled, yet. </p>
890
891<p>Also some operators such as <a href="command-line-options.html#blur">-blur</a>, <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>, will modify their handling of the
892color channels if the '<code>alpha</code>' channel is also enabled by <a href="command-line-options.html#channel">-channel</a>. Generally this done to ensure that
893fully-transparent colors are treated as being fully-transparent, and thus any
894underlying 'hidden' color has no effect on the final results. Typically
895resulting in 'halo' effects. The newer <a href="command-line-options.html#morphology">-morphology</a>
896convolution equivalents however does have a understanding of the 'Sync' flag
897and will thus handle transparency correctly by default. </p>
898
899<p>As a alpha channel is optional within images, some operators will read the
900color channels of an image as a greyscale alpha mask, when the image has no
901alpha channel present, and the <a href="command-line-options.html#channel">-channel</a> setting tells
902the operator to apply the operation using alpha channels. The <a href="command-line-options.html#clut">-clut</a> operator is a good example of this. </p>
903
904
905
906<div style="margin: auto;">
907 <h3 class="magick-header"><a id="charcoal"></a>-charcoal <var>factor</var></h3>
908</div>
909
910<p class="magick-description">Simulate a charcoal drawing.</p>
911
912<div style="margin: auto;">
913 <h3 class="magick-header"><a id="chop"></a>-chop <var>geometry</var></h3>
914</div>
915
916<p class="magick-description">Remove pixels from the interior of an image.</p>
917
918<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <var>width</var>
919and <var>height</var> given in the of the <var>size</var>
920portion of the <var>geometry</var> argument give the number of
921columns and rows to remove. The <var>offset</var> portion of
922the <var>geometry</var> argument is influenced by
923a <a href="command-line-options.html#gravity">-gravity</a> setting, if present.</p>
924
925<p>The <a href="command-line-options.html#chop">-chop</a> option removes entire rows and columns,
926and moves the remaining corner blocks leftward and upward to close the gaps.</p>
927
928<p>While it can remove internal rows and columns of pixels, it is more
929typically used with as <a href="command-line-options.html#gravity">-gravity</a> setting and zero
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]930offsets so as to remove a single edge from an image. Compare this to <a href="command-line-options.html#shave">-shave</a> which removes equal numbers of pixels from opposite
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]931sides of the image. </p>
932
933<p>Using <a href="command-line-options.html#chop">-chop</a> effectively undoes the results of a <a href="command-line-options.html#splice">-splice</a> that was given the same <var>geometry</var> and <a href="command-line-options.html#gravity">-gravity</a> settings. </p>
934
935<div style="margin: auto;">
936 <h3 class="magick-header"><a id="clamp"></a>-clamp</h3>
937</div>
938
939<p class="magick-description">set each pixel whose value is below zero to zero and any the pixel whose value is above the quantum range to the quantum range (e.g. 65535) otherwise the pixel value remains unchanged.</p>
940
941<div style="margin: auto;">
942 <h3 class="magick-header"><a id="clip"></a>-clip</h3>
943</div>
944
945<p class="magick-description">Apply the clipping path if one is present.</p>
946
947<p>If a clipping path is present, it is applied to subsequent operations.</p>
948
949<p>For example, in the command</p>
950
951<pre>
952convert cockatoo.tif -clip -negate negated.tif
953</pre>
954
955<p>only the pixels within the clipping path are negated.</p>
956
957<p>The <a href="command-line-options.html#clip">-clip</a> feature requires SVG support. If the SVG
958delegate library is not present, the option is ignored.</p>
959
960<p>Use <a href="command-line-options.html#clip">+clip</a> to disable clipping for subsequent operations.</p>
961
962<div style="margin: auto;">
963 <h3 class="magick-header"><a id="clip-mask"></a>-clip-mask</h3>
964</div>
965
966<p class="magick-description">Clip the image as defined by this mask.</p>
967
968<p>Use the alpha channel of the current image as a mask. Any areas that is
969white is not modified by any of the 'image processing operators' that follow,
970until the mask is removed. Pixels in the black areas of the clip mask are
971modified per the requirements of the operator. </p>
972
973<p>In some ways this is similar to (though not the same) as defining
974a rectangular <a href="command-line-options.html#region">-region</a>, or using the negative of the
975mask (third) image in a three image <a href="command-line-options.html#composite">-composite</a>,
976operation. </p>
977
978<p>Use <a href="command-line-options.html#clip-mask">+clip-mask</a> to disable clipping for subsequent operations.</p>
979
980<div style="margin: auto;">
981 <h3 class="magick-header"><a id="clip-path"></a>-clip-path <var>id</var></h3>
982</div>
983
984<p class="magick-description">Clip along a named path from the 8BIM profile.</p>
985
986<p>This is identical to <a href="command-line-options.html#clip">-clip</a> except choose a specific clip path in the event the image has more than one path available. </p>
987
988<p>Use <a href="command-line-options.html#clip-path">+clip-path</a> to disable clipping for subsequent operations.</p>
989
990<div style="margin: auto;">
991 <h3 class="magick-header"><a id="clone"></a>-clone <var>index(s)</var></h3>
992</div>
993
994<p class="magick-description">make a clone of an image (or images).</p>
995
996<p>Inside parenthesis (where the operator is normally used) it will make a
997clone of the images from the last 'pushed' image sequence, and adds them to
998the end of the current image sequence. Outside parenthesis
999(not recommended) it clones the images from the current image sequence. </p>
1000
1001<p>Specify the image by its index in the sequence. The first image is index
10020. Negative indexes are relative to the end of the sequence; for
1003example, <code>−1</code>
1004represents the last image of the sequence. Specify a range of images with a
1005dash (e.g. <code>0−4</code>). Separate multiple indexes with commas but no
1006spaces (e.g. <code>0,2,5</code>). A value of '<code>0−−1</code> will
1007effectively clone all the images. </p>
1008
1009<p>The <a href="command-line-options.html#clone">+clone</a> will simply make a copy of the last image
1010in the image sequence, and is thus equivalent to using a argument of
1011'<code>−1</code>'. </p>
1012
1013<div style="margin: auto;">
1014 <h3 class="magick-header"><a id="clut"></a>-clut</h3>
1015</div>
1016
1017<p class="magick-description">Replace the channel values in the first image using each corresponding channel in the second image as a <b>c</b>olor <b>l</b>ook<b>u</b>p <b>t</b>able.</p>
1018
1019<p>The second (LUT) image is ordinarily a gradient image containing the
1020histogram mapping of how each channel should be modified. Typically it is a
1021either a single row or column image of replacement color values. If larger
1022than a single row or column, values are taken from a diagonal line from
1023top-left to bottom-right corners.</p>
1024
1025<p>The lookup is further controlled by the <a href="command-line-options.html#interpolate">-interpolate</a> setting, which is especially handy for an
1026LUT which is not the full length needed by the ImageMagick installed Quality
1027(Q) level. Good settings for this are the '<code>bilinear</code>' and
1028'<code>bicubic</code>' interpolation settings, which give smooth color
1029gradients, and the '<code>integer</code>' setting for a direct, unsmoothed
1030lookup of color values. </p>
1031
1032<p>This operator is especially suited to replacing a grayscale image with a
1033specific color gradient from the CLUT image. </p>
1034
1035<p>Only the channel values defined by the <a href="command-line-options.html#channel">-channel</a>
1036setting will have their values replaced. In particular, since the default <a href="command-line-options.html#channel">-channel</a> setting is <code>RGB</code>, this means that
1037transparency (alpha/matte channel) is not affected, unless the <a href="command-line-options.html#channel">-channel</a> setting is modified. When the alpha channel is
1038set, it is treated by the <a href="command-line-options.html#clut">-clut</a> operator in the same way
1039as the other channels, implying that alpha/matte values are replaced using the
1040alpha/matte values of the original image. </p>
1041
1042<p>If either the image being modified, or the lookup image, contains no
1043transparency (i.e. <a href="command-line-options.html#alpha">-alpha</a> is turned 'off') but the <a href="command-line-options.html#channel">-channel</a> setting includes alpha replacement, then it is
1044assumed that image represents a gray-scale gradient which is used for the
1045replacement alpha values. That is you can use a gray-scale CLUT image to
1046adjust a existing images alpha channel, or you can color a gray-scale image
1047using colors form CLUT containing the desired colors, including transparency.
1048</p>
1049
1050<p>See also <a href="command-line-options.html#hald-clut">-hald-clut</a> which replaces colors
1051according to the lookup of the full color RGB value from a 2D representation
1052of a 3D color cube. </p>
1053
1054
1055<div style="margin: auto;">
1056 <h3 class="magick-header"><a id="coalesce"></a>-coalesce</h3>
1057</div>
1058
1059<p class="magick-description">Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</p>
1060
1061<p>Overlay each image in an image sequence according to
1062its <a href="command-line-options.html#dispose">-dispose</a> meta-data, to reproduce the look of
1063an animation at each point in the animation sequence. All images should be
1064the same size, and are assigned appropriate GIF disposal settings for the
1065animation to continue working as expected as a GIF animation. Such frames
1066are more easily viewed and processed than the highly optimized GIF overlay
1067images. </p>
1068
1069<p>The animation can be re-optimized after processing using
1070the <a href="command-line-options.html#layers">-layers</a> method '<code>optimize</code>', although
1071there is no guarantee that the restored GIF animation optimization is
1072better than the original. </p>
1073
1074
1075<div style="margin: auto;">
1076 <h3 class="magick-header"><a id="colorize"></a>-colorize <var>value</var></h3>
1077</div>
1078
1079<p class="magick-description">Colorize the image by an amount specified by <var>value</var> using the color specified by the most recent <a href="command-line-options.html#fill">-fill</a> setting.</p>
1080
1081<p>Specify the amount of colorization as a percentage. Separate colorization
1082values can be applied to the red, green, and blue channels of the image with
1083a comma-delimited list of colorization
1084values (e.g., <code>-colorize 0,0,50</code>).</p>
1085
1086<div style="margin: auto;">
1087 <h3 class="magick-header"><a id="colormap"></a>-colormap <var>type</var></h3>
1088</div>
1089
1090<p class="magick-description">Define the colormap type.</p>
1091
1092<p>The <var>type</var> can be <code>shared</code> or <code>private</code>.</p>
1093
1094<p>This option only applies when the default X server visual
1095is <code>PseudoColor</code> or <code>GrayScale</code>. Refer
1096to <a href="command-line-options.html#visual">-visual</a> for more details. By default,
1097a shared colormap is allocated. The image shares colors with
1098other X clients. Some image colors could be approximated,
1099therefore your image may look very different than intended.
1100If <code>private</code> is chosen, the image colors appear exactly
1101as they are defined. However, other clients may go <var>technicolor</var>
1102when the image colormap is installed.</p>
1103
1104<div style="margin: auto;">
1105 <h3 class="magick-header"><a id="colors"></a>-colors <var>value</var></h3>
1106</div>
1107
1108<p class="magick-description">Set the preferred number of colors in the image.</p>
1109
1110<p>The actual number of colors in the image may be less than your request,
1111but never more. Note that this a color reduction option. Images with fewer
1112unique colors than specified by <var>value</var> will have any
1113duplicate or unused colors removed. The ordering of an existing color
1114palette may be altered. When converting an image from color to grayscale,
1115it is more efficient to convert the image to the gray colorspace before
1116reducing the number of colors. Refer to
1117the <a href="quantize.html">
1118color reduction algorithm</a> for more details.</p>
1119
1120<div style="margin: auto;">
1121 <h3 class="magick-header"><a id="color-matrix"></a>-color-matrix <var>matrix</var></h3>
1122</div>
1123
1124<p class="magick-description">apply color correction to the image.</p>
1125
1126<p>This option permits saturation changes, hue rotation, luminance to alpha,
1127and various other effects. Although variable-sized transformation matrices
1128can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1129for CMYKA (or RGBA with offsets). The matrix is similar to those used by
1130Adobe Flash except offsets are in column 6 rather than 5 (in support of
1131CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1132
1133<p>As an example, to add contrast to an image with offsets, try this command:</p>
1134
1135<pre>
1136convert kittens.jpg -color-matrix \
1137 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1138 0.0 1.5 0.0 0.0, 0.0, -0.157 \
1139 0.0 0.0 1.5 0.0, 0.0, -0.157 \
1140 0.0 0.0 0.0 1.0, 0.0, 0.0 \
1141 0.0 0.0 0.0 0.0, 1.0, 0.0 \
1142 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
1143</pre>
1144<div style="margin: auto;">
1145 <h3 class="magick-header"><a id="colorspace"></a>-colorspace <var>value</var></h3>
1146</div>
1147
1148<p class="magick-description">Set the image colorspace.</p>
1149
1150<p>Choices are:</p>
1151
1152<pre>
1153CMY CMYK Gray HCL
1154HCLp HSB HSI HSL
1155HSV HWB Lab LCHab
1156LCHuv LMS Log Luv
1157OHTA Rec601YCbCr Rec709YCbCr RGB
1158scRGB sRGB Transparent xyY
1159XYZ YCbCr YCC YDbDr
1160YIQ YPbPr YUV
1161</pre>
1162
1163<p>To print a complete list of colorspaces, use <a href="command-line-options.html#list">-list colorspace</a>.</p>
1164
1165<p>For a more accurate color conversion to or from the linear RGB, CMYK, or grayscale colorspaces, use the <a href="command-line-options.html#profile">-profile</a> option. Note, ImageMagick assumes the sRGB colorspace if the image format does not indicate otherwise. For colorspace conversion, the gamma function is first removed to produce linear RGB.</p>
1166
1167<table class="table table-condensed table-striped">
1168 <caption>Conversion of RGB to Other Color Spaces</caption>
1169 <tr><th valign="middle">CMY</th></tr>
1170 <tr><td valign="middle">C=<var>QuantumRange</var>−R</td></tr>
1171 <tr><td valign="middle">M=<var>QuantumRange</var>−G</td></tr>
1172 <tr><td valign="middle">Y=<var>QuantumRange</var>−B</td></tr>
1173 <tr><th valign="middle">CMYK — starts with CMY from above</th></tr>
1174 <tr><td valign="middle">K=min(C,Y,M)</td></tr>
1175 <tr><td valign="middle">C=<var>QuantumRange</var>*(C−K)/(<var>QuantumRange</var>−K)</td></tr>
1176 <tr><td valign="middle">M=<var>QuantumRange</var>*(M−K)/(<var>QuantumRange</var>−K)</td></tr>
1177 <tr><td valign="middle">Y=<var>QuantumRange</var>*(Y−K)/(<var>QuantumRange</var>−K)</td></tr>
1178
1179 <tr><th valign="middle">Gray</th></tr>
1180 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1181
1182 <tr><th valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1183 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1184 <tr><td valign="middle">S=distance from axis outward</td></tr>
1185 <tr><td valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <var>intensity-like</var></td></tr>
1186
1187 <tr><th valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr>
1188 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1189 <tr><td valign="middle">S=distance from axis outward</td></tr>
1190 <tr><td valign="middle">L=distance along axis from bottom upward; L=0.5*max(R,G,B) + 0.5*min(R,G,B); <var>intensity-like</var></td></tr>
1191
1192 <tr><th valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1193 <tr><td valign="middle">Hue (complicated equation)</td></tr>
1194 <tr><td valign="middle">Whiteness (complicated equation)</td></tr>
1195 <tr><td valign="middle">Blackness (complicated equation)</td></tr>
1196
1197 <tr><th valign="middle">LAB</th></tr>
1198 <tr><td valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1199 <tr><td valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1200 <tr><td valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1201
1202 <tr><th valign="middle">LOG</th></tr>
1203 <tr><td valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1204 <tr><td valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1205 <tr><td valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1206
1207 <tr><th valign="middle">OHTA — approximates principal components transformation</th></tr>
1208 <tr><td valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <var>intensity-like</var></td></tr>
1209 <tr><td valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1210 <tr><td valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1211
1212 <tr><th valign="middle">Rec601Luma</th></tr>
1213 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1214
1215 <tr><th valign="middle">Rec601YCbCr</th></tr>
1216 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1217 <tr><td valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1218 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1219
1220 <tr><th valign="middle">Rec709Luma</th></tr>
1221 <tr><td valign="middle">Gray=0.212656*R+0.715158*G+0.072186*B</td></tr>
1222
1223 <tr><th valign="middle">Rec709YCbCr</th></tr>
1224 <tr><td valign="middle">Y=0.212656*R+0.715158*G+0.072186*B; <var>intensity-like</var></td></tr>
1225 <tr><td valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1226 <tr><td valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1227
1228 <tr><th valign="middle">sRGB</th></tr>
1229 <tr><td valign="middle">if R ≤ .0.0031308 then Rs=R/12.92 else Rs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1230 <tr><td valign="middle">if G ≤ .0.0031308 then Gs=B/12.92 else Gs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1231 <tr><td valign="middle">if B ≤ .0.0031308 then Bs=B/12.92 else Bs=1.055 R ^ (1.0 / 2.4) ? 0.055</td></tr>
1232
1233 <tr><th valign="middle">XYZ</th></tr>
1234 <tr><td valign="middle">X=0.4124564*R+0.3575761*G+0.1804375*B</td></tr>
1235 <tr><td valign="middle">Y=0.2126729*R+0.7151522*G+0.0721750*B</td></tr>
1236 <tr><td valign="middle">Z=0.0193339*R+0.1191920*G+0.9503041*B</td></tr>
1237
1238 <tr><th valign="middle">YCC</th></tr>
1239 <tr><td valign="middle">Y=(0.298839*R+0.586811*G+0.114350*B) (with complicated scaling); <var>intensity-like</var></td></tr>
1240 <tr><td valign="middle">C1=(−0.298839*R−0.586811*G+0.88600*B) (with complicated scaling)</td></tr>
1241 <tr><td valign="middle">C2=(0.70100*R−0.586811*G−0.114350*B) (with complicated scaling)</td></tr>
1242
1243 <tr><th valign="middle">YCbCr</th></tr>
1244 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1245 <tr><td valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1246 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1247
1248 <tr><th valign="middle">YIQ</th></tr>
1249 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1250 <tr><td valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1251 <tr><td valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1252
1253 <tr><th valign="middle">YPbPr</th></tr>
1254 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1255 <tr><td valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1256 <tr><td valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1257
1258 <tr><th valign="middle">YUV</th></tr>
1259 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1260 <tr><td valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1261 <tr><td valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1262</table>
1263
1264<p>Note the scRGB colorspace requires HDRI support otherwise it behaves just like linear RGB.</p>
1265
1266<div style="margin: auto;">
1267 <h3 class="magick-header"><a id="combine"></a>-combine</h3>
1268</div>
1269
1270<p class="magick-description">Combine one or more images into a single image.</p>
1271
1272<p>The channels (previously set by <a href="command-line-options.html#channel">-channel</a>) of the
1273combined image are taken from the grayscale values of each image in the
1274sequence, in order. For the default -channel setting of <code>RGB</code>, this
1275means the first image is assigned to the <code>Red</code> channel, the second
1276to the <code>Green</code> channel, the third to the <code>Blue</code>.</p>
1277
1278<p>This option can be thought of as the inverse to <a href="command-line-options.html#separate">-separate</a>, so long as the channel settings are the same.
1279Thus, in the following example, the final image should be a copy of the
1280original. </p>
1281
1282<pre>
1283convert original.png -channel RGB -separate sepimage.png
1284convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \
1285 -combine imagecopy.png
1286</pre>
1287
1288<div style="margin: auto;">
1289 <h3 class="magick-header"><a id="comment"></a>-comment <var>string</var></h3>
1290</div>
1291
1292<p class="magick-description">Embed a comment in an image.</p>
1293
1294<p>This option sets the comment meta-data of an image read in after this
1295option has been given. To modify a comment of images already in memory use
1296"<code><a href="command-line-options.html#set">-set</a> comment</code>". </p>
1297
1298<p>The comment can contain special format characters listed in the <a href="escape.html">Format and
1299Print Image Properties</a>. These attributes are expanded when the comment
1300is finally assigned to the individual images. </p>
1301
1302<p>If the first character of <var>string</var> is <var>@</var>, the image comment is read from a file titled by the
1303remaining characters in the string. Comments read in from a file are literal;
1304no embedded formatting characters are recognized.</p>
1305
1306<p>Comment meta-data are not visible on the image itself. To do that use the
1307<a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1308instead.</p>
1309
1310<p>For example,</p>
1311
1312<pre>
1313-comment "%m:%f %wx%h" bird.miff
1314</pre>
1315
1316<p>produces an image comment of <code>MIFF:bird.miff 512x480</code> (assuming
1317that the image <code>bird.miff</code> has a width of 512 and a height of
1318480.</p>
1319
1320<div style="margin: auto;">
1321 <h3 class="magick-header"><a id="compare"></a>-compare</h3>
1322</div>
1323
1324<p class="magick-description">mathematically and visually annotate the difference between an image and its reconstruction</p>
1325
1326<p>This is a convert version of "<code>compare</code>" for two same sized images. The syntax is as follows, but other metrics are allowed.</p>
1327
1328<pre>
1329convert image.png reference.png -metric RMSE -compare \ <br> difference.png
1330</pre>
1331
1332<p>To get the metric value use the string format "%[distortion]".</p>
1333
1334<pre>
1335convert image.png reference.png -metric RMSE -compare -format \
1336 "%[distortion]" info:
1337</pre>
1338
1339<div style="margin: auto;">
1340 <h3 class="magick-header"><a id="complex"></a>-complex <var>operator</var></h3>
1341</div>
1342
1343<p class="magick-description">perform complex mathematics on an image sequence</p>
1344
1345Choose from these operators:
1346
1347<pre>
1348add
1349conjugate
1350divide
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]1351magnitude-phase
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]1352multiply
1353real-imaginary
1354subtract
1355</pre>
1356
1357<p>Optionally specify the <code>divide</code> operator SNR with <code><a href="command-line-options.html#define">-define</a> complex:snr=float</code>.</p>
1358
1359<div style="margin: auto;">
1360 <h3 class="magick-header"><a id="compose"></a>-compose <var>operator</var></h3>
1361</div>
1362
1363<p class="magick-description">Set the type of image composition.</p>
1364
1365<p>See <a href="compose.html">Alpha Compositing</a> for
1366a detailed discussion of alpha compositing.</p>
1367
1368<p>This setting effects image processing operators that merge two (or more)
1369images together in some way. This includes the operators,
1370<a href="command-line-options.html#composite">-compare</a>,
1371<a href="command-line-options.html#composite">-composite</a>,
1372<a href="command-line-options.html#layers">-layers</a> composite,
1373<a href="command-line-options.html#flatten">-flatten</a>,
1374<a href="command-line-options.html#mosaic">-mosaic</a>,
1375<a href="command-line-options.html#layers">-layers</a> merge,
1376<a href="command-line-options.html#border">-border</a>,
1377<a href="command-line-options.html#frame">-frame</a>,
1378and <a href="command-line-options.html#extent">-extent</a>. </p>
1379
1380<p>It is also one of the primary options for the "<code>composite</code>"
1381command. </p>
1382
1383
1384<div style="margin: auto;">
1385 <h3 class="magick-header"><a id="composite"></a>-composite</h3>
1386</div>
1387
1388<p class="magick-description">Perform alpha composition on two images and an optional mask</p>
1389
1390<p>Take the first image 'destination' and overlay the second 'source' image
1391according to the current <a href="command-line-options.html#compose">-compose</a> setting. The location
1392of the 'source' or 'overlay' image is controlled according to <a href="command-line-options.html#geometry">-geometry</a>, and <a href="command-line-options.html#geometry">-geometry</a>
1393settings. </p>
1394
1395<p>If a third image is given this is treated as a gray-scale blending 'mask' image
1396relative to the first 'destination' image. This mask is blended with the
1397source image. However for the '<code>displace</code>' compose method, the
1398mask is used to provide a separate Y-displacement image instead. </p>
1399
1400<p>If a <a href="command-line-options.html#compose">-compose</a> method requires extra numerical
1401arguments or flags these can be provided by setting the <a href="command-line-options.html#set">-set</a> '<code>option:compose:args</code>'
1402appropriately for the compose method. </p>
1403
1404<p>Some <a href="command-line-options.html#compose">-compose</a> methods can modify the 'destination'
1405image outside the overlay area. You can disable this by setting the special <a href="command-line-options.html#set">-set</a> '<code>option:compose:outside-overlay</code>'
1406to '<code>false</code>'. </p>
1407
1408<p>The SVG compositing specification requires that color and opacity values range between zero and QuantumRange inclusive. You can permit values outside this range with this option: <a href="command-line-options.html#set">-set</a> '<code>option:compose:clamp=false</code></p>
1409
1410
1411<div style="margin: auto;">
1412 <h3 class="magick-header"><a id="compress"></a>-compress <var>type</var></h3>
1413</div>
1414
1415<p class="magick-description">Use pixel compression specified by <var>type</var> when writing the image.</p>
1416
1417<p>Choices are: <code>None</code>, <code>BZip</code>, <code>Fax</code>, <code>Group4</code>, <code>JPEG</code>, <code>JPEG2000</code>, <code>Lossless</code>, <code>LZW</code>, <code>RLE</code> or <code>Zip</code>.</p>
1418
1419<p>To print a complete list of compression types, use <a href="command-line-options.html#list">-list
1420compress</a>.</p>
1421
1422<p>Specify <a href="command-line-options.html#compress">+compress</a> to store the binary image in an
1423uncompressed format. The default is the compression type of the specified
1424image file.</p>
1425
1426<p>If <code>LZW</code> compression is specified but LZW compression has not been
1427enabled, the image data is written in an uncompressed LZW format that can be
1428read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1429
1430<p><code>Lossless</code> refers to lossless JPEG, which is only available if the
1431JPEG library has been patched to support it. Use of lossless JPEG is generally
1432not recommended.</p>
1433
1434<p>
1435When writing an ICO file, you may request that the images be encoded in
1436PNG format, by specifying <code>Zip</code> compression.</p>
1437
1438<p>
1439When writing a JNG file, specify <code>Zip</code> compression to request that
1440the alpha channel be encoded in PNG "IDAT" format, or <code>JPEG</code>
1441to request that it be encoded in JPG "JDAA" format.</p>
1442
1443<p>Use the <a href="command-line-options.html#quality">-quality</a> option to set the compression level
1444to be used by JPEG, PNG, MIFF, and MPEG encoders.
1445Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to set the
1446sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling
1447the chroma channels.</p>
1448
1449<div style="margin: auto;">
1450 <h3 class="magick-header"><a id="connected-components"></a>-connected-components <var>connectivity</var></h3>
1451</div>
1452
1453<p class="magick-description">connected-components uniquely labeled, choose from 4 or 8 way connectivity.</p>
1454
1455<p>Use <code><a href="command-line-options.html#define">-define</a> connected-components:verbose=true</code> to output statistics associated with each unique label.</p>
1456
1457<div style="margin: auto;">
1458 <h3 class="magick-header"><a id="contrast"></a>-contrast</h3>
1459</div>
1460
1461<p class="magick-description">Enhance or reduce the image contrast.</p>
1462
1463<p>This option enhances the intensity differences between the lighter and
1464darker elements of the image. Use <a href="command-line-options.html#contrast">-contrast</a> to enhance
1465the image or <a href="command-line-options.html#contrast">+contrast</a> to reduce the image
1466contrast.</p>
1467
1468<p>For a more pronounced effect you can repeat the option:</p>
1469
1470<pre>
1471convert rose: -contrast -contrast rose_c2.png
1472</pre>
1473
1474<div style="margin: auto;">
1475 <h3 class="magick-header"><a id="contrast-stretch"></a>-contrast-stretch <var>black-point</var><br>-contrast-stretch <var>black-point</var>{x<var>white-point</var>}{<var>%</var>}}</h3>
1476</div>
1477
1478<p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
1479
1480<p>While performing the stretch, black-out at most <var>black-point</var> pixels and white-out at most <var>white-point</var> pixels. Or, if percent is used, black-out at most
1481<var>black-point %</var> pixels and white-out at most <var>white-point %</var> pixels.</p>
1482
1483<p>Prior to ImageMagick 6.4.7-0, <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> will black-out at most <var>black-point</var> pixels and white-out at most <var>total pixels
1484minus white-point</var> pixels. Or, if percent is used, black-out at most <var>black-point %</var> pixels and white-out at most <var>100% minus white-point %</var> pixels.</p>
1485
1486<p>Note that <code>-contrast-stretch 0</code> will modify the image such that
1487the image's min and max values are stretched to 0 and <var>QuantumRange</var>, respectively, without any loss of data due to burn-out or
1488clipping at either end. This is not the same as <a href="command-line-options.html#normalize">-normalize</a>, which is equivalent to <code>-contrast-stretch 0.15x0.05%</code> (or
1489prior to ImageMagick 6.4.7-0, <code>-contrast-stretch 2%x99%</code>).</p>
1490
1491<p>Internally operator works by creating a histogram bin, and then uses that
1492bin to modify the image. As such some colors may be merged together when they
1493originally fell into the same 'bin'. </p>
1494
1495<p>All the channels are normalized in concert by the came amount so as to
1496preserve color integrity, when the default <a href="command-line-options.html#channel">+channel</a>
1497setting is in use. Specifying any other <a href="command-line-options.html#channel">-channel</a>
1498setting will normalize the RGB channels independently.</p>
1499
1500<p>See also <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect'
1501normalization of mathematical images. </p>
1502
1503<p>This operator is under review for re-development. </p>
1504
1505
1506<div style="margin: auto;">
1507 <h3 class="magick-header"><a id="convolve"></a>-convolve <var>kernel</var></h3>
1508</div>
1509
1510<p class="magick-description">Convolve an image with a user-supplied convolution kernel.</p>
1511
1512<p>The <var>kernel</var> is a matrix specified as
1513a comma-separated list of integers (with no spaces), ordered left-to right,
1514starting with the top row. Presently, only odd-dimensioned kernels are
1515supported, and therefore the number of entries in the specified <var>kernel</var> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25,
15167<sup>2</sup>=49, etc. </p>
1517
1518<p>Note that the <a href="command-line-options.html#convolve">‑convolve</a> operator supports the <a href="command-line-options.html#bias">‑bias</a> setting. This option shifts the convolution so that
1519positive and negative results are relative to a user-specified bias value.
1520This is important for non-HDRI compilations of ImageMagick when dealing with
1521convolutions that contain negative as well as positive values. This is
1522especially the case with convolutions involving high pass filters or edge
1523detection. Without an output bias, the negative values is clipped at zero.
1524</p>
1525
1526<p>When using an ImageMagick with the HDRI compile-time setting, <a href="command-line-options.html#bias">‑bias</a> is not needed, as ImageMagick is able to store/handle any
1527negative results without clipping to the color value range (0..QuantumRange).
1528See the discussion on HDRI implementations of ImageMagick on the page <a href="high-dynamic-range.html">High
1529Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
1530<a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1531entry. </p>
1532
1533
1534<div style="margin: auto;">
1535 <h3 class="magick-header"><a id="copy"></a>-copy <var>geometry</var> <var>offset</var></h3>
1536</div>
1537
1538<p class="magick-description">copy pixels from one area of an image to another.</p>
1539
1540<div style="margin: auto;">
1541 <h3 class="magick-header"><a id="crop"></a>-crop <var>geometry</var>{<var>@</var>}{<var>!</var>}</h3>
1542</div>
1543
1544<p class="magick-description">Cut out one or more rectangular regions of the image.</p>
1545
1546<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1547
1548<p>The <var>width</var> and <var>height</var> of the <var>geometry</var> argument give the size of the image that remains
1549after cropping, and <var>x</var> and <var>y</var> in the
1550<var>offset</var> (if present) gives the location of the top left
1551corner of the cropped image with respect to the original image. To specify the
1552amount to be removed, use <a href="command-line-options.html#shave">-shave</a> instead.</p>
1553
1554<p>If the <var>x</var> and <var>y</var> offsets are
1555present, a single image is generated, consisting of the pixels from the
1556cropping region. The offsets specify the location of the upper left corner of
1557the cropping region measured downward and rightward with respect to the upper
1558left corner of the image. If the <a href="command-line-options.html#gravity">-gravity</a> option is
1559present with <code>NorthEast</code>, <code>East</code>, or <code>SouthEast</code>
1560gravity, it gives the distance leftward from the right edge of the image to
1561the right edge of the cropping region. Similarly, if the <a href="command-line-options.html#gravity">-gravity</a> option is present with <code>SouthWest</code>,
1562<code>South</code>, or <code>SouthEast</code> gravity, the distance is measured
1563upward between the bottom edges.</p>
1564
1565<p>If the <var>x</var> and <var>y</var> offsets are
1566omitted, a set of tiles of the specified geometry, covering the entire input
1567image, is generated. The rightmost tiles and the bottom tiles are smaller if
1568the specified geometry extends beyond the dimensions of the input image.</p>
1569
1570<p>You can add the <var>@</var> to the geometry argument to equally divide the image into the number of tiles generated.</p>
1571
1572<p>By adding a exclamation character flag to the geometry argument, the
1573cropped images virtual canvas page size and offset is set as if the
1574geometry argument was a viewport or window. This means the canvas page size
1575is set to exactly the same size you specified, the image offset set
1576relative top left corner of the region cropped. </p>
1577
1578<p>If the cropped image 'missed' the actual image on its virtual canvas, a
1579special single pixel transparent 'missed' image is returned, and a 'crop
1580missed' warning given. </p>
1581
1582<p>It might be necessary to <a href="command-line-options.html#repage">+repage</a> the image prior to
1583cropping the image to ensure the crop coordinate frame is relocated to the
1584upper-left corner of the visible image.
1585
1586Similarly you may want to use <a href="command-line-options.html#repage">+repage</a> after cropping to
1587remove the page offset that will be left behind. This is especially true when
1588you are going to write to an image format such as PNG that supports an image
1589offset.</p>
1590
1591<div style="margin: auto;">
1592 <h3 class="magick-header"><a id="cycle"></a>-cycle <var>amount</var></h3>
1593</div>
1594
1595<p class="magick-description">displace image colormap by amount.</p>
1596
1597<p><var>Amount</var> defines the number of positions each
1598colormap entry is shifted.</p>
1599
1600
1601<div style="margin: auto;">
1602 <h3 class="magick-header"><a id="debug"></a>-debug <var>events</var></h3>
1603</div>
1604
1605<p class="magick-description">enable debug printout.</p>
1606
1607<p>The <code>events</code> parameter specifies which events are to be logged. It
1608can be either <code>None</code>, <code>All</code>, <code>Trace</code>, or
1609a comma-separated list consisting of one or more of the following domains:
1610<code>Accelerate</code>, <code>Annotate</code>, <code>Blob</code>, <code>Cache</code>,
1611<code>Coder</code>, <code>Configure</code>, <code>Deprecate</code>,
1612<code>Exception</code>, <code>Locale</code>, <code>Render</code>,
1613<code>Resource</code>, <code>Security</code>, <code>TemporaryFile</code>,
1614<code>Transform</code>, <code>X11</code>, or <code>User</code>. </p>
1615
1616
1617<p>For example, to log cache and blob events, use.</p>
1618
1619<pre>
1620convert -debug "Cache,Blob" rose: rose.png
1621</pre>
1622
1623<p>The <code>User</code> domain is normally empty, but developers can log user
1624events in their private copy of ImageMagick.</p>
1625
1626<p>To print the complete list of debug methods, use <a href="command-line-options.html#list">-list
1627debug</a>.</p>
1628
1629<p>Use the <a href="command-line-options.html#log">-log</a> option to specify the format for debugging
1630output.</p>
1631
1632<p>Use <a href="command-line-options.html#debug">+debug</a> to turn off all logging.</p>
1633
1634<p>Debugging may also be set using the <code>MAGICK_DEBUG</code> <a href="resources.html#environment">environment variable</a>. The allowed values for the <code>MAGICK_DEBUG</code>
1635environment variable are the same as for the <a href="command-line-options.html#debug">-debug</a>
1636option.</p>
1637
1638
1639<div style="margin: auto;">
1640 <h3 class="magick-header"><a id="decipher"></a>-decipher <var>filename</var></h3>
1641</div>
1642
1643<p class="magick-description">Decipher and restore pixels that were previously transformed by <a href="command-line-options.html#encipher">-encipher</a>.</p>
1644
1645<p>Get the passphrase from the file specified by <var>filename</var>.</p>
1646
1647<p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or
1648Decipher an Image</a>.</p>
1649
1650
1651<div style="margin: auto;">
1652 <h3 class="magick-header"><a id="deconstruct"></a>-deconstruct</h3>
1653</div>
1654
1655<p class="magick-description">find areas that has changed between images </p>
1656
1657<p>Given a sequence of images all the same size, such as produced by <a href="command-line-options.html#coalesce">-coalesce</a>, replace the second and later images, with
1658a smaller image of just the area that changed relative to the previous image.
1659</p>
1660
1661<p>The resulting sequence of images can be used to optimize an animation
1662sequence, though will not work correctly for GIF animations when parts of the
1663animation can go from opaque to transparent. </p>
1664
1665<p>This option is actually equivalent to the <a href="command-line-options.html#layers">-layers</a>
1666method '<code>compare-any</code>'. </p>
1667
1668
1669<div style="margin: auto;">
1670 <h3 class="magick-header"><a id="define"></a>-define <var>key</var>{<var>=value</var>}<var>...</var></h3>
1671</div>
1672
1673<p class="magick-description">add specific global settings generally used to control coders and image processing operations.</p>
1674
1675<p>This option creates one or more definitions for coders and decoders to use
1676while reading and writing image data. Definitions are generally used to
1677control image file format coder modules, and image processing operations,
1678beyond what is provided by normal means. Defined settings are listed in <a href="command-line-options.html#verbose">-verbose</a> information ("<code>info:</code>" output format)
1679as "Artifacts". </p>
1680
1681<p>If <var>value</var> is missing for a definition, an empty-valued
1682definition of a flag is created with that name. This used to control on/off
1683options. Use <a href="command-line-options.html#define">+define key</a> to remove definitions
1684previously created. Use <a href="command-line-options.html#define">+define "*"</a> to remove all
1685existing definitions.</p>
1686
1687<p>The same 'artifact' settings can also be defined using the <a href="command-line-options.html#set">-set "option:<var>key</var>" "<var>value</var>"</a> option, which also allows the use of <a href="escape.html">Format and Print Image
1688Properties</a> in the defined value. </p>
1689
1690<p>The <var>option</var> and <var>key</var> are case-independent (they are
1691converted to lowercase for use within the decoders) while the <var>value</var>
1692is case-dependent.</p>
1693
1694<p>Such settings are global in scope, and affect all images and operations. </p>
1695
1696<p>The following definitions are just some of the artifacts that are
1697available:</p>
1698
1699<table class="table table-condensed table-striped">
1700 <tr>
1701 <td>bmp:format=<var>value</var></td>
1702 <td> valid values are <var>bmp2</var>, <var>bmp3</var>,
1703 and <var>bmp4</var>. This option can be useful when the
1704 method of prepending "BMP2:" to the output filename is inconvenient or
1705 is not available, such as when using the <a href="mogrify.html">mogrify</a> utility.</td>
1706 </tr>
1707
1708 <tr>
1709 <td>colorspace:auto-grayscale=<var>on|off</var></td>
1710 <td>prevent automatic conversion to grayscale inside coders that support grayscale.</td>
1711 </tr>
1712
1713 <tr>
1714 <td>complex:snr=<var>value</var></td>
1715 <td>Set the divide SNR constant<a href="command-line-options.html#complex">-complex</a></td>
1716 </tr>
1717
1718 <tr>
1719 <td>compose:args=<var>arguments</var></td>
1720 <td>Sets certain compose argument values when using convert ... -compose ...
1721 -composite. See <a href="http://www.imagemagick.org/www/compose.html">Image Composition</a></td>
1722 </tr>
1723
1724 <tr>
1725 <td>compose:clamp=<var>on|off</var></td>
1726 <td>set each pixel whose value is below zero to zero and any the pixel whose value is above the quantum range to the quantum range (e.g. 65535) otherwise the pixel value remains unchanged. Define supported in ImageMagick 6.9.1-3 and above.</td>
1727 </tr>
1728
1729 <tr>
1730 <td>convolve:scale=<var>{kernel_scale}[!^] [,{origin_addition}] [%]</var></td>
1731 <td>Defines the kernel scaling. The special flag ! automatically scales to
1732 full dynamic range. The ! flag can be used in combination with a factor or
1733 percent. The factor or percent is then applied after the automatic scaling.
1734 An example is 50%!. This produces a result 50% darker than full dynamic
1735 range scaling. The ^ flag assures the kernel is 'zero-summing', for
1736 example when some values are positive and some are negative as in edge
1737 detection kernels. The origin addition adds that value to the center
1738 pixel of the kernel. This produces and effect that is like adding the image
1739 that many times to the result of the filtered image. The typical value
1740 is 1 so that the original image is added to the result of the convolution.
1741 The default is 0.</td>
1742 </tr>
1743
1744 <tr>
1745 <td>convolve:showkernel=<var>1</var></td>
1746 <td>Outputs (to 'standard error') all the information about a specified <a href="command-line-options.html#morphology">-morphology convolve</a> kernel.</td>
1747 </tr>
1748
1749 <tr>
1750 <td>dcm:display-range=<var>reset</var></td>
1751 <td>Sets the display range to the minimum and maximum pixel values for the
1752 DCM image format.</td>
1753 </tr>
1754
1755 <tr>
1756 <td>dds:cluster-fit=<var>true|false</var></td>
1757 <td>Enables the dds cluster-fit.</td>
1758 </tr>
1759
1760 <tr>
1761 <td>dds:compression=<var>dxt1|dxt5|none</var></td>
1762 <td>Sets the dds compression.</td>
1763 </tr>
1764
1765 <tr>
1766 <td>dds:mipmaps=<var>value</var></td>
1767 <td>Sets the dds number of mipmaps.</td>
1768 </tr>
1769
1770 <tr>
1771 <td>dds:weight-by-alpha=<var>true|false</var></td>
1772 <td>Enables the dds alpha weighting.</td>
1773 </tr>
1774
1775 <tr>
1776 <td>delegate:bimodal=<var>true</var></td>
1777 <td>Specifies direct conversion from Postscript to PDF.</td>
1778 </tr>
1779
1780 <tr>
1781 <td>distort:scale=<var>value</var></td>
1782 <td>Sets the output scaling factor for use with <a href="command-line-options.html#distort">-distort</a></td>
1783 </tr>
1784
1785 <tr>
1786 <td>distort:viewport=<var>WxH+X+Y</var></td>
1787 <td>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a></td>
1788 </tr>
1789
1790 <tr>
1791 <td>dot:layout-engine=<var>value</var></td>
1792 <td>Specifies the layout engine for the DOT image format (e.g.
1793 <code>neato</code>).</td>
1794 </tr>
1795
1796 <tr>
1797 <td>filter:option=<var>value</var></td>
1798 <td>Set a filter option for use with <a href="command-line-options.html#resize">-resize</a>.
1799 See <a href="command-line-options.html#filter">-filter</a> for details.</td>
1800 </tr>
1801
1802 <tr>
1803 <td>fourier:normalize=<var>inverse</var></td>
1804 <td>Sets the location for the FFT/IFT normalization as use by
1805 <a href="command-line-options.html#fft">+-fft</a> and <a href="command-line-options.html#ift">+-ift</a>. The default is
1806 <var>forward</var>.</td>
1807 </tr>
1808
1809 <tr>
1810 <td>h:format=<var>value</var></td>
1811 <td>Set the image encoding format use when writing a C-style header.
1812 <var>format</var> can be any output format supported by ImageMagick
1813 except for <var>h</var> and <var>magick</var></td>. If this
1814 option is omitted, the default is <var>GIF</var> for PseudoClass
1815 images and <var>PNM</var> for DirectClass images.
1816 </tr>
1817
1818 <tr>
1819 <td>icon:auto-resize</td>
1820 <td>Automatically stores multiple sizes when writing an ico image
1821 (requires a 256x256 input image).</td>
1822 </tr>
1823
1824 <tr>
1825 <td>jp2:layer-number=<var>value</var></td>
1826 <td>Sets the maximum number of quality layers to decode. Same for JPT, JC2,
1827 and J2K</td>
1828 </tr>
1829
1830 <tr>
1831 <td>jp2:number-resolutions=<var>value</var></td>
1832 <td>Sets the number of resolutions to encode.Same for JPT, JC2, and J2K</td>
1833 </tr>
1834
1835 <tr>
1836 <td>jp2:progression-order=<var>value</var></td>
1837 <td>choose from LRCP, RLCP, RPCL, PCRL or CPRL. Same for JPT, JC2, and
1838 J2K</td>
1839 </tr>
1840
1841 <tr>
1842 <td>jp2:quality=<var>value,value...</var></td>
1843 <td>Sets the quality layer PSNR, given in dB. The order is from left to
1844 right in ascending order. The default is a single lossless quality layer.
1845 Same for JPT, JC2, and J2K</td>
1846 </tr>
1847
1848 <tr>
1849 <td>jp2:rate=<var>value</var></td>
1850 <td>Specify the compression factor to use while writing JPEG-2000 files. The
1851 compression factor is the reciprocal of the compression ratio. The valid
1852 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined,
1853 this value overrides the -quality setting. A quality setting of 75
1854 results in a rate value of 0.06641. Same for JPT, JC2, and J2K</td>
1855 </tr>
1856
1857 <tr>
1858 <td>jp2:reduce-factor=<var>value</var></td>
1859 <td>Sets the number of highest resolution levels to be discarded.Same for
1860 JPT, JC2, and J2K</td>
1861 </tr>
1862
1863 <tr>
1864 <td>jpeg:block-smoothing=<var>on|off</var></td>
1865 <td>&amp;nbsp</td>
1866 </tr>
1867
1868 <tr>
1869 <td>jpeg:colors=<var>value</var></td>
1870 <td>Set the desired number of colors and let the JPEG encoder do the
1871 quantizing.</td>
1872 </tr>
1873
1874 <tr>
1875 <td>jpeg:dct-method=<var>value</var></td>
1876 <td>Choose from <code>default</code>, <code>fastest</code>,
1877 <code>float</code>, <code>ifast</code>, and <code>islow</code>.</td>
1878 </tr>
1879
1880 <tr>
1881 <td>jpeg:extent=<var>value</var></td>
1882 <td>Restrict the maximum JPEG file size, for example <code>-define
1883 jpeg:extent=400KB</code>. The JPEG encoder will search for the highest
1884 compression quality level that results in an output file that does not
1885 exceed the value. The <code>-quality</code> option is ignored if it
1886 is also present.</td>
1887 </tr>
1888
1889 <tr>
1890 <td>jpeg:fancy-upsampling=<var>on|off</var></td>
1891 <td>&amp;nbsp</td>
1892 </tr>
1893
1894 <tr>
1895 <td>jpeg:optimize-coding=<var>on|off</var></td>
1896 <td>&amp;nbsp</td>
1897 </tr>
1898
1899 <tr>
1900 <td>jpeg:q-table=<var>table</var></td>
1901 <td>&amp;nbsp</td>
1902 </tr>
1903
1904 <tr>
1905 <td>jpeg:sampling-factor=<var>sampling-factor-string</var></td>
1906 <td>&amp;nbsp</td>
1907 </tr>
1908
1909 <tr>
1910 <td>jpeg:size=<var>geometry</var></td>
1911 <td>Set the size hint of a JPEG image, for
1912 example, <code>-define jpeg:size=128x128</code>.
1913 It is most useful for increasing performance and reducing the memory
1914 requirements when reducing the size of a large JPEG image.</td>
1915 </tr>
1916
1917 <tr>
1918 <td>json:features</td>
1919 <td>includes features in verbose information</td>
1920 </tr>
1921
1922 <tr>
1923 <td>json:limit</td>
1924 <td>&amp;nbsp</td>
1925 </tr>
1926
1927 <tr>
1928 <td>json:locate</td>
1929 <td>&amp;nbsp</td>
1930 </tr>
1931
1932 <tr>
1933 <td>json:moments</td>
1934 <td>includes image moments in verbose information</td>
1935 </tr>
1936
1937 <tr>
1938 <td>magick:format=<var>value</var></td>
1939 <td>Set the image encoding format use when writing a C-style header.
1940 This is the same as "h:format=format" described above.</td>.
1941 </tr>
1942
1943 <tr>
1944 <td>mng:need-cacheoff</td>
1945 <td>turn playback caching off for streaming MNG.</td>
1946 </tr>
1947
1948 <tr>
1949 <td>morphology:compose=<var>compose-method</var></td>
1950 <td>Specifies how to merge results generated by multiple<a href="command-line-options.html#morphology">-morphology</a> kernel. The default is none. One
1951 typical value is 'lighten' as used, for example, with the sobel edge
1952 kernels. </td>
1953 </tr>
1954
1955 <tr>
1956 <td>morphology:showkernel=<var>1</var></td>
1957 <td>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</td>
1958 </tr>
1959
1960 <tr>
1961 <td>pcl:fit-to-page=<var>true</var></td>
1962
1963 </tr><tr>
1964 <td>pdf:fit-page=<var>geometry</var></td>
1965 <td> geometry specifies the scaling dimensions for resizing when the PDF is
1966 being read. The geometry is either WxH{%} or page size. No offsets are
1967 allowed. (introduced in IM 6.8.8-8)</td>
1968 </tr>
1969
1970 <tr>
1971 <td>pdf:fit-to-page=<var>true</var></td>
1972 <td>&amp;nbsp</td>
1973 </tr>
1974
1975 <tr>
1976 <td>pdf:use-cropbox=<var>true</var></td>
1977 <td>&amp;nbsp</td>
1978 </tr>
1979
1980 <tr>
1981 <td>pdf:use-trimbox=<var>true</var></td>
1982 <td>&amp;nbsp</td>
1983 </tr>
1984
1985 <tr>
1986 <td>png:bit-depth=<var>value</var></td>
1987 <td>&amp;nbsp</td>
1988 </tr>
1989 <tr>
1990 <td>png:color-type=<var>value</var></td>
1991 <td>desired bit-depth and color-type for PNG output. You can force the PNG
1992 encoder to use a different bit-depth and color-type than it would have
1993 normally selected, but only if this does not cause any loss of image
1994 quality. Any attempt to reduce image quality is treated as an error and no
1995 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
1996 can use these "defines" to cause it to be written as an 8-bit grayscale,
1997 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
1998 you cannot force it to be written as a grayscale or indexed PNG. If you
1999 wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
2000 <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
2001 reduce the image quality prior to using the PNG encoder. Note that in
2002 indexed PNG files, "bit-depth" refers to the number of bits per index,
2003 which can be 1, 2, 4, or 8. In such files, the color samples always have
2004 8-bit depth.</td>
2005 </tr>
2006
2007 <tr>
2008 <td>png:compression-filter=<var>value</var></td>
2009 <td> valid values are 0 through 9. 0-4 are the corresponding PNG filters,
2010 5 means adaptive filtering except for images with a colormap, 6 means
2011 adaptive filtering for all images, 7 means MNG "loco" compression, 8 means
2012 Z_RLE strategy with adaptive filtering, and 9 means Z_RLE strategy with no
2013 filtering.</td>
2014 </tr>
2015
2016 <tr>
2017 <td>png:compression-level=<var>value</var></td>
2018 <td> valid values are 0 through 9, with 0 providing the least but fastest
2019 compression and 9 usually providing the best and always the slowest.</td>
2020 </tr>
2021
2022 <tr>
2023 <td>png:compression-strategy=<var>value</var></td>
2024 <td> valid values are 0 through 4, meaning default, filtered, huffman_only,
2025 rle, and fixed ZLIB compression strategy. If you are using an old zlib
2026 that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
2027 values 3 and 4, respectively, will use the zlib default strategy
2028 instead.</td>
2029 </tr>
2030
2031 <tr>
2032 <td>png:format=<var>value</var></td>
2033 <td> valid values are <var>png8</var>, <var>png24</var>,
2034 <var>png32</var>, <var>png48</var>,
2035 <var>png64</var>, and <var>png00</var>.
2036 This property can be useful for specifying
2037 the specific PNG format to be used, when the usual method of prepending the
2038 format name to the output filename is inconvenient, such as when writing
2039 a PNG-encoded ICO file or when using <a href="mogrify.html">mogrify</a>.
2040 Value = <var>png8</var> reduces the number of colors to 256,
2041 only one of which may be fully transparent, if necessary. The other
2042 values do not force any reduction of quality; it is an error to request
2043 a format that cannot represent the image data without loss (except that
2044 it is allowed to reduce the bit-depth from 16 to 8 for all formats).
2045 Value = <var>png24</var> and <var>png48</var>
2046 allow transparency, only if a single color is fully transparent and that
2047 color does not also appear in an opaque pixel; such transparency is
2048 written in a PNG <code>tRNS</code> chunk.
2049 Value = <var>png00</var> causes the image to inherit its
2050 color-type and bit-depth from the input image, if the input was also
2051 a PNG.</td>
2052 </tr>
2053
2054 <tr>
2055 <td>png:exclude-chunk=<var>value</var></td>
2056
2057 </tr><tr>
2058 <td>png:include-chunk=<var>value</var></td>
2059 <td>ancillary chunks to be excluded from or included in PNG output.
2060
2061 <p>The <var>value</var> can be the name of a PNG chunk-type such
2062 as <var>bKGD</var>, a comma-separated list of chunk-names
2063 (which can include the word <var>date</var>, the word
2064 <var>all</var>, or the word <var>none</var>).
2065 Although PNG chunk-names are case-dependent, you can use all lowercase
2066 names if you prefer.</p>
2067
2068 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
2069 of the PNG encoder and have no effect on the PNG decoder.</p>
2070
2071 <p>As a special case, if the <code>sRGB</code> chunk is excluded and
2072 the <code>gAMA</code> chunk is included, the <code>gAMA</code> chunk will
2073 only be written if gamma is not 1/2.2, since most decoders assume
2074 sRGB and gamma=1/2.2 when no colorspace information is included in
2075 the PNG file. Because the list is processed from left to right, you
2076 can achieve this with a single define:</p>
2077
2078<pre>
2079-define png:include-chunk=none,gAMA
2080</pre>
2081
2082 <p>As a special case, if the <code>sRGB</code> chunk is not excluded and
2083 the PNG encoder recognizes that the image contains the sRGB ICC profile,
2084 the PNG encoder will write the <code>sRGB</code> chunk instead of the
2085 entire ICC profile. To force the PNG encoder to write the sRGB
2086 profile as an <code>iCCP</code> chunk in the output PNG instead of the
2087 <code>sRGB</code> chunk, exclude the <code>sRGB</code> chunk.</p>
2088
2089 <p>The critical PNG chunks <code>IHDR</code>, <code>PLTE</code>,
2090 <code>IDAT</code>, and <code>IEND</code> cannot be excluded. Any such
2091 entries appearing in the list will be ignored.</p>
2092
2093 <p>If the ancillary PNG <code>tRNS</code> chunk is excluded and the
2094 image has transparency, the PNG colortype is forced to be 4 or 6
2095 (GRAY_ALPHA or RGBA). If the image is not transparent, then the
2096 <code>tRNS</code> chunk isn't written anyhow, and there is no effect
2097 on the PNG colortype of the output image.</p>
2098
2099 <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2100 following for PNG output:</p>
2101
2102<pre>
2103-define png:exclude-chunk=EXIF,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date
2104</pre>
2105
2106 <p>The default behavior is to include all known PNG ancillary chunks
2107 plus ImageMagick's private <code>vpAg</code> ("virtual page") chunk,
2108 and to exclude all PNG chunks that are unknown to ImageMagick,
2109 regardless of their PNG "copy-safe" status as described in the
2110 PNG specification.</p>
2111
2112 <p>Any chunk names that are not known to ImageMagick are ignored
2113 if they appear in either the "include-chunk" or "exclude-chunk" list.
2114 The ancillary chunks currently known to ImageMagick are
2115 <code>bKGD</code>, <code>cHRM</code>, <code>gAMA</code>, <code>iCCP</code>,
2116 <code>oFFs</code>, <code>pHYs</code>, <code>sRGB</code>, <code>tEXt</code>,
2117 <code>tRNS</code>, <code>vpAg</code>, and <code>zTXt</code>.</p>
2118
2119 <p>You can also put <code>date</code> in the list to include or exclude
2120 the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2121 inserts in the output PNG.</p></td>
2122 </tr>
2123
2124 <tr>
2125 <td>png:preserve-colormap[=<var>true</var>]</td>
2126 <td>Use the existing image-&gt;colormap. Normally the PNG encoder will
2127 try to optimize the palette, eliminating unused entries and putting
2128 the transparent colors first. If this flag is set, that behavior
2129 is suppressed.</td>
2130 </tr>
2131
2132 <tr>
2133 <td>png:preserve-iCCP[=<var>true</var>]</td>
2134 <td>By default, the PNG decoder and encoder examine any ICC profile
2135 that is present, either from an <code>iCCP</code> chunk in the PNG
2136 input or supplied via an option, and if the profile is recognized
2137 to be the sRGB profile, converts it to the <code>sRGB</code> chunk.
2138 You can use <code>-define png:preserve-iCCP</code> to prevent
2139 this from happening; in such cases the <code>iCCP</code> chunk
2140 will be read or written and no <code>sRGB</code> chunk will be
2141 written. There are some ICC profiles that claim to be sRGB but
2142 have various errors that cause them to be rejected by libpng16; such
2143 profiles are recognized anyhow and converted to the <code>sRGB</code>
2144 chunk, but are rejected if the <code>-define png:preserve-iCCP</code>
2145 is present. Note that not all "sRGB" ICC profiles are recognized
2146 yet; we will add them to the list as we encounter them.</td>
2147 </tr>
2148
2149 <tr>
2150 <td>png:swap-bytes[=<var>true</var>]</td>
2151 <td>The PNG specification requires that any multi-byte integers be stored in
2152 network byte order (MSB-LSB endian). This option allows you to
2153 fix any invalid PNG files that have 16-bit samples stored incorrectly
2154 in little-endian order (LSB-MSB). The "-define png:swap-bytes" option
2155 must appear before the input filename on the commandline. The swapping
2156 is done during the libpng decoding operation.</td>
2157 </tr>
2158
2159 <tr>
2160 <td>profile:skip=<var>name1,name2,...</var></td>
2161 <td>Skip the named profile[s] when reading the image. Use skip="*" to
2162 skip all named profiles in the image. Many named profiles exist,
2163 including ICC, EXIF, APP1, IPTC, XMP, and others.</td>
2164 </tr>
2165
2166 <tr>
2167 <td>ps:imagemask</td>
2168 <td>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create
2169 Postscript files that render bilevel images with the Postscript imagemask
2170 operator instead of the image operator.</td>
2171 </tr>
2172
2173 <tr>
2174 <td>quantum:format=<var>type</var></td>
2175 <td>Set the type to <code>floating-point</code> to specify a floating-point
2176 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2177 to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2178 included, the result is a single precision floating point format.
2179 If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2180 double precision floating point format.</td>
2181 </tr>
2182
2183 <tr>
2184 <td>quantum:polarity=<var>photometric-interpretation</var></td>
2185 <td>Set the photometric-interpretation of an image (typically for TIFF image
2186 file format) to either <code>min-is-black</code> (default) or
2187 <code>min-is-white</code>.</td>
2188 </tr>
2189
2190 <tr>
2191 <td>sample:offset=<var>geometry</var></td>
2192 <td>Location of the sampling point within the sub-region being sampled,
2193 expressed as percentages (see <a href="command-line-options.html#sample">-sample</a>).</td>
2194 </tr>
2195
2196 <tr>
2197 <td>showkernel=<var>1</var></td>
2198 <td>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</td>
2199 </tr>
2200
2201 <tr>
2202 <td>stream:buffer-size=<var>value</var></td>
2203 <td>Set the stream buffer size. Select 0 for unbuffered I/O.</td>
2204 </tr>
2205
2206 <tr>
2207 <td>tiff:alpha=<var>associated|unassociated|unspecified</var></td>
2208 <td>Specify the alpha extra samples as associated, unassociated or unspecified </td>
2209 </tr>
2210
2211 <tr>
2212 <td>tiff:endian=<var>msb|lsb</var></td>
2213 <td>&amp;nbsp</td>
2214 </tr>
2215
2216 <tr>
2217 <td>tiff:exif-properties=<var>false</var></td>
2218 <td>Skips reading the EXIF properties.</td>
2219 </tr>
2220
2221 <tr>
2222 <td>tiff:fill-order=<var>msb|lsb</var></td>
2223 <td>&amp;nbsp</td>
2224 </tr>
2225
2226 <tr>
2227 <td>tiff:ignore-layers=<var>true</var></td>
2228 <td>Ignores the photoshop layers.</td>
2229 </tr>
2230
2231 <tr>
2232 <td>tiff:ignore-tags=<var>comma-separate-list-of-tag-IDs</var></td>
2233 <td>Allows one or more tag ID values to be ignored.</td>
2234 </tr>
2235
2236 <tr>
2237 <td>tiff:rows-per-strip=<var>value</var></td>
2238 <td>Sets the number of rows per strip</td>
2239 </tr>
2240
2241 <tr>
2242 <td>tiff:tile-geometry=<var>WxH</var></td>
2243 <td>Sets the tile size for pyramid tiffs. Requires the suffix
2244 PTIF: before the outputname</td>
2245 </tr>
2246</table>
2247
2248<p>For example, to create a postscript file that will render only the black
2249pixels of a bilevel image, use:</p>
2250
2251<pre>
2252convert bilevel.tif -define ps:imagemask eps3:stencil.ps
2253</pre>
2254
2255<p>Set attributes of the image registry by prefixing the value with
2256<code>registry:</code>. For example, to set a temporary path to put work files,
2257use:</p>
2258
2259<pre>
2260-define registry:temporary-path=/data/tmp
2261</pre>
2262
2263<div style="margin: auto;">
2264 <h3 class="magick-header"><a id="delay"></a>-delay <var>ticks</var> <br>-delay <var>ticks</var>x<var>ticks-per-second</var> {<var>&lt;</var>} {<var>&gt;</var>}</h3>
2265</div>
2266
2267<p class="magick-description">display the next image after pausing.</p>
2268
2269<p>This option is useful for regulating the animation of image sequences
2270<var>ticks/ticks-per-second</var> seconds must expire before the display of the
2271next image. The default is no delay between each showing of the image
2272sequence. The default ticks-per-second is 100.</p>
2273
2274<p>Use <code>&gt;</code> to change the image delay <var>only</var> if its current
2275value exceeds the given delay. <code>&lt;</code> changes the image delay
2276<var>only</var> if current value is less than the given delay. For example, if
2277you specify <code>30&gt;</code> and the image delay is 20, the image delay does
2278not change. However, if the image delay is 40 or 50, the delay it is changed
2279to 30. Enclose the given delay in quotation marks to prevent the
2280<code>&lt;</code> or <code>&gt;</code> from being interpreted by your shell as
2281a file redirection.</p>
2282
2283
2284<div style="margin: auto;">
2285 <h3 class="magick-header"><a id="delete"></a>-delete <var>indexes</var></h3>
2286</div>
2287
2288<p class="magick-description">delete the images specified by index, from the image sequence.</p>
2289
2290<p>Specify the image by its index in the sequence. The first image is index
22910. Negative indexes are relative to the end of the sequence, for example, -1
2292represents the last image of the sequence. Specify a range of images with
2293a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use
2294<code>+delete</code> to delete the last image in the current image sequence.</p>
2295
2296
2297<div style="margin: auto;">
2298 <h3 class="magick-header"><a id="density"></a>-density <var>width</var><br>-density <var>width</var>x<var>height</var></h3>
2299</div>
2300
2301<p class="magick-description">Set the horizontal and vertical resolution of an image for rendering to devices.</p>
2302
2303<p>This option specifies the image resolution to store while encoding a raster
2304image or the canvas resolution while rendering (reading) vector formats such
2305as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2306provides the unit of measure to apply when rendering to an output device or
2307raster image. The default unit of measure is in dots per inch (DPI). The <a href="command-line-options.html#units">-units</a> option may be used to select dots per centimeter
2308instead.</p>
2309
2310<p>The default resolution is 72 dots per inch, which is equivalent to one
2311point per pixel (Macintosh and Postscript standard). Computer screens are
2312normally 72 or 96 dots per inch, while printers typically support 150, 300,
2313600, or 1200 dots per inch. To determine the resolution of your display, use
2314a ruler to measure the width of your screen in inches, and divide by the
2315number of horizontal pixels (1024 on a 1024x768 display).</p>
2316
2317<p>If the file format supports it, this option may be used to update the
2318stored image resolution. Note that Photoshop stores and obtains image
2319resolution from a proprietary embedded profile. If this profile is not
2320stripped from the image, then Photoshop will continue to treat the image using
2321its former resolution, ignoring the image resolution specified in the standard
2322file header.</p>
2323
2324<p>The <a href="command-line-options.html#density">-density</a> option sets an <var>attribute</var> and
2325does not alter the underlying raster image. It may be used to adjust the
2326rendered size for desktop publishing purposes by adjusting the scale applied
2327to the pixels. To resize the image so that it is the same size at a different
2328resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2329
2330<div style="margin: auto;">
2331 <h3 class="magick-header"><a id="depth"></a>-depth <var>value</var></h3>
2332</div>
2333
2334<p class="magick-description">depth of the image.</p>
2335
2336<p>This the number of bits in a color sample within a pixel. Use this option
2337to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2338or CMYK, or to change the depth of any image after it has been read.</p>
2339
2340<div style="margin: auto;">
2341 <h3 class="magick-header"><a id="descend"></a>-descend</h3>
2342</div>
2343
2344<p class="magick-description">obtain image by descending window hierarchy.</p>
2345
2346<div style="margin: auto;">
2347 <h3 class="magick-header"><a id="deskew"></a>-deskew <var>threshold</var></h3>
2348</div>
2349
2350<p class="magick-description">straighten an image. A threshold of 40% works for most images.</p>
2351
2352<p>Use <a href="command-line-options.html#set">-set</a> <code>option:deskew:auto-crop
2353<var>width</var></code> to auto crop the image. The set argument is the pixel
2354width of the image background (e.g 40).</p>
2355
2356<div style="margin: auto;">
2357 <h3 class="magick-header"><a id="despeckle"></a>-despeckle</h3>
2358</div>
2359
2360<p class="magick-description">reduce the speckles within an image.</p>
2361
2362<div style="margin: auto;">
2363 <h3 class="magick-header"><a id="direction"></a>-direction <var>type</var></h3>
2364</div>
2365
2366<p class="magick-description">render text right-to-left or left-to-right.</p>
2367
2368<div style="margin: auto;">
2369 <h3 class="magick-header"><a id="displace"></a>-displace <var>horizontal-scale</var><br>-displace <var>horizontal-scale</var>x<var>vertical-scale</var></h3>
2370</div>
2371
2372<p class="magick-description">shift image pixels as defined by a displacement map.</p>
2373
2374<p>With this option, the 'overlay' image, and optionally the 'mask' image,
2375is used as a displacement map, which is used to displace the lookup of
2376what part of the 'background' image is seen at each point of the overlaid
2377area. Much like the displacement map is a 'lens' that redirects light shining
2378through it so as to present a distorted view the original 'background' image
2379behind it. </p>
2380
2381<p>Any perfect grey areas of the displacement map produce a zero
2382displacement of the image. Black areas produce the given maximum negative
2383displacement of the lookup point, while white produce a maximum positive
2384displacement of the lookup. </p>
2385
2386<p>Note that it is the lookup of the 'background' that is displaced, not a
2387displacement of the image itself. As such an area of the displacement map
2388containing 'white' will have the lookup point 'shifted' by a positive amount,
2389and thus generating a copy of the destination image to the right/downward from
2390the correct position. That is the image will look like it may have been
2391'shifted' in a negative left/upward direction. Understanding this is a very
2392important in understanding how displacement maps work. </p>
2393
2394<p>The given arguments define the maximum amount of displacement in pixels
2395that a particular map can produce. If the displacement scale is large enough
2396it is also possible to lookup parts of the 'background' image that lie well
2397outside the bounds of the displacement map itself. That is you could very
2398easily copy a section of the original image from outside the overlay area
2399into the overlay area. </p>
2400
2401<p>The '%' flag makes the displacement scale relative to the size of the
2402overlay image (100% = half width/height of image). Using '!' switches
2403percentage arguments to refer to the destination image size instead.
2404these flags were added as of IM v6.5.3-5.</p>
2405
2406<p>Normally a single grayscale displacement map is provided, which with the
2407given scaling values will determine a single direction (vector) in which
2408displacements can occur (positively or negatively). However, if you also
2409specify a third image which is normally used as a <var>mask</var>,
2410the <var>composite image</var> is used for horizontal X
2411displacement, while the <var>mask image</var> is used for vertical Y
2412displacement. This allows you to define completely different displacement
2413values for the X and Y directions, and allowing you to lookup any point within
2414the <var>scale</var> bounds. In other words each pixel can lookup
2415any other nearby pixel, producing complex 2 dimensional displacements, rather
2416than a simple 1 dimensional vector displacements. </p>
2417
2418<p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2419you can use the 'red' channel of the overlay image to specify the horizontal
2420or X displacement, and the 'green' channel for the vertical or Y displacement.
2421</p>
2422
2423<p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2424mask the transparency of the destination image. However areas outside the
2425overlaid areas will not be effected. </p>
2426
2427
2428<div style="margin: auto;">
2429 <h3 class="magick-header"><a id="display"></a>-display <var>host:display[.screen]</var></h3>
2430</div>
2431
2432<p class="magick-description">Specifies the X server to contact.</p>
2433
2434<p>This option is used with convert for obtaining image or font from this
2435X server. See <var>X(1)</var>.</p>
2436
2437<div style="margin: auto;">
2438 <h3 class="magick-header"><a id="dispose"></a>-dispose <var>method</var></h3>
2439</div>
2440
2441<p class="magick-description">define the GIF disposal image setting for images that are being created or read in. </p>
2442
2443<p>The layer disposal method defines the way each the displayed image is to be
2444modified after the current 'frame' of an animation has finished being
2445displayed (after its 'delay' period), but before the next frame on an
2446animation is to be overlaid onto the display. </p>
2447
2448<p>Here are the valid methods:</p>
2449
2450<dl class="dl-horizontal">
2451<dt>Undefined</dt><dd>0: No disposal specified (equivalent to '<code>none</code>').</dd>
2452<dt>None</dt><dd>1: Do not dispose, just overlay next frame image.</dd>
2453<dt>Background</dt><dd>2: Clear the frame area with the background color.</dd>
2454<dt>Previous</dt><dd>3: Clear to the image prior to this frames overlay.</dd>
2455</dl>
2456
2457<p>You can also use the numbers given above, which is what the GIF format
2458uses internally to represent the above settings. </p>
2459
2460<p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2461
2462<p>Use <a href="command-line-options.html#dispose">+dispose</a>, turn off the setting and prevent
2463resetting the layer disposal methods of images being read in. </p>
2464
2465<p>Use <a href="command-line-options.html#set">-set</a> '<code>dispose</code>' method to set the image
2466disposal method for images already in memory.</p>
2467
2468<div style="margin: auto;">
2469 <h3 class="magick-header"><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <var>value</var></h3>
2470</div>
2471
2472<p class="magick-description">maximum RMSE for subimage match (default 0.2).</p>
2473
2474
2475<div style="margin: auto;">
2476 <h3 class="magick-header"><a id="dissolve"></a>-dissolve <var>src_percent</var>[x<var>dst_percent</var>]</h3>
2477</div>
2478
2479<p class="magick-description">dissolve an image into another by the given percent.</p>
2480
2481<p>The opacity of the composite image is multiplied by the given percent, then
2482it is composited 'over' the main image. If <var>src_percent</var>
2483is greater than 100, start dissolving the main image so it becomes
2484transparent at a value of '<code>200</code>'. If both percentages
2485are given, each image are dissolved to the percentages given. </p>
2486
2487<p>Note that dissolve percentages do not add, two opaque images dissolved
2488'50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2489images, you would need to use dissolve values of '50,100'. </p>
2490
2491<div style="margin: auto;">
2492 <h3 class="magick-header"><a id="distort"></a>-distort <var>method arguments</var></h3>
2493</div>
2494
2495<p class="magick-description">distort an image, using the given <var>method</var> and its required <var>arguments</var>.</p>
2496
2497<p>The <var>arguments</var> is a single string containing a list
2498of floating point numbers separated by commas or spaces. The number of
2499and meaning of the floating point values depends on the distortion <var>method</var> being used. </p>
2500
2501<p>Choose from these distortion types:</p>
2502
2503<table class="table table-condensed table-striped">
2504 <tr>
2505 <th style="width: 8%">Method</th>
2506 <th>Description</th>
2507 </tr>
2508
2509 <tr>
2510 <td>ScaleRotateTranslate <br> SRT</td>
2511 <td>
2512 Distort image by first scaling and rotating about a given 'center',
2513 before translating that 'center' to the new location, in that order. It
2514 is an alternative method of specifying a 'Affine' type of
2515 distortion, but without shearing effects. It also provides a good way
2516 of rotating and displacing a smaller image for tiling onto a larger
2517 background (IE 2-dimensional animations). <br>
2518
2519 The number of arguments determine the specific meaning of each
2520 argument for the scales, rotation, and translation operations. <br>
2521
2522 <dl class="dl-horizontal">
2523 <dt>2:</dt><dd><var>Scale Angle</var></dd>
2524 <dt>3:</dt><dd><var>X,Y Angle</var></dd>
2525 <dt>4:</dt><dd><var>X,Y Scale Angle</var></dd>
2526 <dt>5:</dt> <dd><var>X,Y ScaleX,ScaleY Angle</var></dd>
2527 <dt>6:</dt> <dd><var>X,Y Scale Angle NewX,NewY</var></dd>
2528 <dt>7:</dt> <dd><var>X,Y ScaleX,ScaleY Angle NewX,NewY</var></dd>
2529 </dl>
2530
2531 This is actually an alternative way of specifying a 2 dimensional linear
2532 'Affine' or 'AffineProjection' distortion. </td> </tr>
2533
2534 <tr>
2535 <td>Affine</td>
2536 <td>
2537 Distort the image linearly by moving a list of at least 3 or more sets
2538 of control points (as defined below). Ideally 3 sets or 12 floating
2539 point values are given allowing the image to be linearly scaled,
2540 rotated, sheared, and translated, according to those three points. See
2541 also the related 'AffineProjection' and 'SRT'
2542 distortions. <br>
2543
2544 More than 3 sets given control point pairs (12 numbers) is least
2545 squares fitted to best match a linear affine distortion. If only 2
2546 control point pairs (8 numbers) are given a two point image translation
2547 rotation and scaling is performed, without any possible shearing,
2548 flipping or changes in aspect ratio to the resulting image. If only one
2549 control point pair is provides the image is only translated, (which may
2550 be a floating point non-integer translation). <br>
2551
2552 This distortion does not include any form of perspective distortion.
2553 </td>
2554
2555 </tr>
2556
2557 <tr>
2558 <td>AffineProjection</td>
2559 <td>
2560 Linearly distort an image using the given Affine Matrix of 6
2561 pre-calculated coefficients forming a set of Affine Equations to map
2562 the source image to the destination image.
2563
2564 <p class="text-center"><var>
2565 s<sub>x</sub>, r<sub>x</sub>,
2566 r<sub>y</sub>, s<sub>y</sub>,
2567 t<sub>x</sub>, t<sub>y</sub>
2568 </var></p>
2569
2570 See <a href="command-line-options.html#affine">-affine</a> setting for more detail, and
2571 meanings of these coefficients. <br>
2572
2573 The distortions 'Affine' and 'SRT' provide
2574 alternative methods of defining this distortion, with ImageMagick doing
2575 the calculations needed to generate the required coefficients. You can
2576 see the internally generated coefficients, by using a <a href="command-line-options.html#verbose">-verbose</a> setting with those other variants. </td>
2577
2578 </tr>
2579
2580 <tr>
2581 <td>BilinearForward<br>
2582 BilinearReverse</td>
2583 <td>
2584 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2585 16 values (see below). Not that lines may not appear straight after
2586 distortion, though the distance between coordinates will remain
2587 consistent. <br>
2588
2589 The 'BilinearForward' is used to map rectangles to any
2590 quadrilateral, while the 'BilinearReverse' form maps any
2591 quadrilateral to a rectangle, while preserving the straight line edges
2592 in each case. <br>
2593
2594 Note that 'BilinearForward' can generate invalid pixels
2595 which will be colored using the <a href="command-line-options.html#mattecolor">-mattecolor</a>
2596 color setting. Also if the quadrilateral becomes 'flipped' the image
2597 may disappear. <br>
2598
2599 There are future plans to produce a true Bilinear distortion that will
2600 attempt to map any quadrilateral to any other quadrilateral, while
2601 preserving edges (and edge distance ratios).
2602
2603 </td>
2604 </tr>
2605
2606 <tr>
2607 <td>Perspective</td>
2608 <td>
2609 Perspective distort the images, using a list of 4 or more sets of
2610 control points (as defined below). More that 4 sets (16 numbers) of
2611 control points provide least squares fitting for more accurate
2612 distortions (for the purposes of image registration and panorama
2613 effects). Less than 4 sets will fall back to a 'Affine'
2614 linear distortion. <br>
2615
2616 Perspective Distorted images ensures that straight lines remain
2617 straight, but the scale of the distorted image will vary. The horizon
2618 is anti-aliased, and the 'sky' color may be set using the
2619 <a href="command-line-options.html#mattecolor">-mattecolor</a> setting. </td>
2620 </tr>
2621
2622 <tr>
2623 <td>PerspectiveProjection </td>
2624 <td>
2625 Do a 'Perspective' distortion biased on a set of 8
2626 pre-calculated coefficients. You can get these coefficients by looking
2627 at the <a href="command-line-options.html#verbose">-verbose</a> output of a
2628 'Perspective' distortion, or by calculating them yourself.
2629 If the last two perspective scaling coefficients are zero, the
2630 remaining 6 represents a transposed 'Affine Matrix'. </td>
2631
2632 </tr>
2633
2634 <tr>
2635 <td>Arc</td>
2636 <td>
2637 Arc the image (variation of polar mapping) over the angle given around
2638 a circle.
2639
2640 <p></p><dl class="dl-horizontal">
2641 <dt>arc_angle</dt>
2642 <dd>The angle over which to arc the image side-to-side</dd>
2643 <dt>rotate_angle</dt>
2644 <dd>Angle to rotate resulting image from vertical center</dd>
2645 <dt>top_radius</dt>
2646 <dd>Set top edge of source image at this radius</dd>
2647 <dt>bottom_radius </dt>
2648 <dd>Set bottom edge to this radius (radial scaling)</dd>
2649 </dl>
2650
2651 The resulting image is always resized to best fit the resulting image,
2652 (as if using <a href="command-line-options.html#distort">+distort</a>) while attempting to
2653 preserve scale and aspect ratio of the original image as much as
2654 possible with the arguments given by the user. All four arguments will
2655 be needed to change the overall aspect ratio of an 'Arc'ed image. <br>
2656
2657 This a variation of a polar distortion designed to try to preserve the
2658 aspect ratio of the image rather than direct Cartesian to Polar
2659 conversion. </td>
2660 </tr>
2661
2662 <tr>
2663 <td>Polar</td>
2664 <td>
2665 Like 'Arc' but do a complete Cartesian to Polar mapping of
2666 the image. that is the height of the input image is mapped to the
2667 radius limits, while the width is wrapped around between the
2668 angle limits. <br>
2669
2670 Arguments: <var>Rmax,Rmin CenterX,CenterY, start,end_angle</var> <br>
2671
2672 All arguments are optional. With <var>Rmin</var> defaulting to zero, the
2673 center to the center of the image, and the angles going from -180 (top)
2674 to +180 (top). If <var>Rmax</var> is given the special value of
2675 '0', the the distance from the center to the nearest edge
2676 is used for the radius of the output image, which will ensure the whole
2677 image is visible (though scaled smaller). However a special value of
2678 '-1' will use the distance from the center to the furthest
2679 corner, This may 'clip' the corners from the input rectangular image,
2680 but will generate the exact reverse of a 'DePolar' with
2681 the same arguments. <br>
2682
2683 If the plus form of distort (<a href="command-line-options.html#distort">+distort</a>) is used
2684 output image center will default to 0,0 of the virtual
2685 canvas, and the image size adjusted to ensure the whole input image is
2686 made visible in the output image on the virtual canvas. </td>
2687
2688 </tr>
2689
2690 <tr>
2691 <td>DePolar</td>
2692 <td>
2693 Uses the same arguments and meanings as a 'Polar' distortion
2694 but generates the reverse Polar to Cartesian distortion. <br>
2695
2696 The special <var>Rmax</var> setting of '0' may however clip
2697 the corners of the input image. However using the special
2698 <var>Rmax</var> setting of '-1' (maximum center to corner
2699 distance) will ensure the whole distorted image is preserved in the
2700 generated result, so that the same argument to 'Polar' will
2701 reverse the distortion re-producing the original.
2702
2703 Note that as this distortion requires the area resampling of a circular
2704 arc, which can not be handled by the builtin EWA resampling function.
2705 As such the normal EWA filters are turned off. It is recommended some
2706 form of 'super-sampling' image processing technique be used to produce
2707 a high quality result. </td>
2708
2709 </tr>
2710
2711 <tr>
2712 <td>Barrel</td>
2713 <td>
2714 Given the four coefficients (A,B,C,D) as defined by <a href="http://wiki.panotools.org/Lens_correction_model">Helmut
2715 Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
2716 correct radial lens distortions. That is in photographs, make straight
2717 lines straight again. <br>
2718
2719 <p class="text-center">Arguments: <var>A B C</var> [ <var>D</var> [
2720 <var>X</var> , <var>Y</var> ] ] <br>
2721 or <var>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2722 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></var>
2723 [ <var>X</var> , <var>Y</var> ] </p>
2724 So that it forms the function
2725 <p class="text-center">Rsrc = r * ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2726 <var>C</var>*r + <var>D</var> )</p>
2727
2728 Where <var>X</var>,<var>Y</var> is the optional center of the distortion
2729 (defaulting to the center of the image). <br>
2730 The second form is typically used to distort images, rather than
2731 correct lens distortions. <br>
2732 </td>
2733
2734 </tr>
2735
2736 <tr>
2737 <td>BarrelInverse</td>
2738 <td>
2739 This is very similar to 'Barrel' with the same set of
2740 arguments, and argument handling. However it uses the inverse
2741 of the radial polynomial,
2742 so that it forms the function
2743 <p class="text-center">Rsrc = r / ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2744 <var>C</var>*r + <var>D</var> )</p>
2745 Note that this is not the reverse of the 'Barrel'
2746 distortion, just a different barrel-like radial distortion method.
2747
2748 </td>
2749 </tr>
2750
2751 <tr>
2752 <td>Shepards</td>
2753 <td>
2754 Distort the given list control points (any number) using an Inverse
2755 Squared Distance Interpolation Method (<a href="http://en.wikipedia.org/wiki/Shepard%27s_method">Shepards
2756 Method</a>). The control points in effect do 'localized' displacement
2757 of the image around the given control point (preserving the look and
2758 the rotation of the area near the control points. For best results
2759 extra control points should be added to 'lock' the positions of the
2760 corners, edges and other unchanging parts of the image, to prevent
2761 their movement. <br>
2762
2763 The distortion has been likened to 'taffy pulling' using nails, or
2764 pins' stuck in a block of 'jelly' which is then moved to the new
2765 position, distorting the surface of the jelly. <br>
2766
2767 Internally it is equivalent to generating a displacement map (see <a href="command-line-options.html#displace">-displace</a>) for source image color look-up using
2768 the <a href="command-line-options.html#sparse-color">-sparse-color</a> method of the same name.
2769
2770 </td>
2771 </tr>
2772
2773</table>
2774
2775<p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
2776distort</a>.</p>
2777
2778<p>Many of the above distortion methods such as '<code>Affine</code>',
2779'<code>Perspective</code>', and '<code>Shepards</code>' use a list control points
2780defining how these points in the given image should be distorted in the
2781destination image. Each set of four floating point values represent a source
2782image coordinate, followed immediately by the destination image coordinate.
2783This produces a list of values such as...</p>
2784<p class="text-center"><var>
2785 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
2786 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
2787 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
2788 ...
2789 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
2790</var></p>
2791<p>where <var>U,V</var> on the source image is mapped to <var>X,Y</var> on the
2792destination image. </p>
2793
2794<p>For example, to warp an image using '<code>perspective</code>' distortion,
2795needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
2796perspective distortion of the built-in "rose:" image. Note how spaces were
2797used to group the 4 sets of coordinate pairs, to make it easier to read and
2798understand.</p>
2799
2800<pre>
2801convert rose: -virtual-pixel black \
2802 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \
2803 rose_3d_rotated.gif"
2804</pre>
2805
2806<p>If more that the required number of coordinate pairs are given for
2807a distortion, the distortion method is 'least squares' fitted to produce the
2808best result for all the coordinate pairs given. If less than the ideal number
2809of points are given, the distort will generally fall back to a simpler form of
2810distortion that can handles the smaller number of coordinates (usually a linear
2811'<code>Affine</code>' distortion). </p>
2812
2813<p>By using more coordinates you can make use of image registration tool to
2814find matching coordinate pairs in overlapping images, so as to improve the
2815'fit' of the distortion. Of course a bad coordinate pair can also make the
2816'fit' worse. Caution is always advised. </p>
2817
2818<p>Colors are acquired from the source image according to a cylindrical
2819resampling <a href="command-line-options.html#filter">-filter</a>, using a special technique known as
2820EWA resampling. This produces very high quality results, especially when
2821images become smaller (minified) in the output, which is very common when
2822using '<code>perspective</code>' distortion. For example here we view
2823a infinitely tiled 'plane' all the way to the horizon. </p>
2824
2825<pre>
2826convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \
2827 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \
2828 checks_tiled.jpg
2829</pre>
2830
2831<p>Note that a infinitely tiled perspective images involving the horizon can
2832be very slow, because of the number of pixels that are compressed to generate
2833each individual pixel close to the 'horizon'. You can turn off EWA
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]2834resampling, by specifying the special <a href="command-line-options.html#filter">-filter</a> setting of
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]2835'<code>point</code>' (recommended if you plan to use super-sampling instead).
2836</p>
2837
2838<p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
2839example, <a href="command-line-options.html#distort">-distort</a> will use the current <a href="command-line-options.html#mattecolor">-mattecolor</a> setting for these pixels. If you do not
2840what these pixels to be visible, set the color to match the rest of the
2841ground. </p>
2842
2843<p>The output image size will by default be the same as the input image. This
2844means that if the part of the distorted image falls outside the viewed area of
2845the 'distorted space', those parts is clipped and lost. However if you use
2846the plus form of the operator (<a href="command-line-options.html#distort">+distort</a>) the operator
2847will attempt (if possible) to show the whole of the distorted image, while
2848retaining a correct 'virtual canvas' offset, for image layering. This offset
2849may need to be removed using <a href="command-line-options.html#repage">+repage</a>, to remove if it
2850is unwanted. </p>
2851
2852<p>Setting <a href="command-line-options.html#verbose">-verbose</a> setting, will cause <a href="command-line-options.html#distort">-distort</a> to attempt to output the internal coefficients,
2853and the <a href="command-line-options.html#fx">-fx</a> equivalent to the distortion, for expert study,
2854and debugging purposes. This many not be available for all distorts. </p>
2855
2856<p>You can alternatively specify a special "<code><a href="command-line-options.html#define">-define</a> distort:viewport={geometry_string}</code>" setting which will
2857specify the size and the offset of the generated 'viewport' image of the
2858distorted image space.</p>
2859
2860<p>Setting a "<code><a href="command-line-options.html#define">-define</a>
2861distort:scale={scale_factor}</code>" will scale the output image (viewport or
2862otherwise) by that factor without changing the viewed contents of the
2863distorted image. This can be used either for 'super-sampling' the image for
2864a higher quality result, or for panning and zooming around the image (with
2865appropriate viewport changes, or post-distort cropping and resizing). </p>
2866
2867<p>Setting "<code><a href="command-line-options.html#define">-define</a> resample:verbose=1</code>"
2868will output the cylindrical filter lookup table created by the EWA (Elliptical
2869Weighted Average) resampling algorithm. Note this table uses a squared radius
2870lookup value. This is typically only used for debugging EWA resampling. </p>
2871
2872
2873<div style="margin: auto;">
2874 <h3 class="magick-header"><a id="distribute-cache"></a>-distribute-cache <var>port</var></h3>
2875</div>
2876
2877<p class="magick-description">launch a distributed pixel cache server. </p>
2878
2879<div style="margin: auto;">
2880 <h3 class="magick-header"><a id="dither"></a>-dither <var>method</var></h3>
2881</div>
2882
2883<p class="magick-description">Apply a Riemersma or Floyd-Steinberg error diffusion dither to
2884images when general color reduction is applied via an option, or automagically
2885when saving to specific formats. This enabled by default.</p>
2886
2887<p>Dithering places two or more colors in neighboring pixels so that to the
2888eye a closer approximation of the images original color is reproduced. This
2889reduces the number of colors needed to reproduce the image but at the cost of
2890a lower level pattern of colors. Error diffusion dithers can use any set of
2891colors (generated or user defined) to an image. </p>
2892
2893<p>Dithering is turned on by default, to turn it off use the plus form of the
2894setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
2895without text or graphic aliasing. Disabling dithering often (but not always)
2896leads to faster process, a smaller number of colors, but more cartoon like
2897image coloring. Generally resulting in 'color banding' effects in areas with
2898color gradients. </p>
2899
2900<p>The color reduction operators <a href="command-line-options.html#colors">-colors</a>, <a href="command-line-options.html#monochrome">-monochrome</a>, <a href="command-line-options.html#remap%20">-remap</a>, and <a href="command-line-options.html#posterize">-posterize</a>, apply dithering to images using the reduced
2901color set they created. These operators are also used as part of automatic
2902color reduction when saving images to formats with limited color support, such
2903as <code>GIF:</code>, <code>XBM:</code>, and others, so dithering may also be used
2904in these cases. </p>
2905
2906<p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
2907to generate purely random dither. Or use <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
2908patterns, using uniform color maps, rather than specific color maps. </p>
2909
2910
2911<div style="margin: auto;">
2912 <h3 class="magick-header"><a id="draw"></a>-draw <var>string</var></h3>
2913</div>
2914
2915<p class="magick-description">Annotate an image with one or more graphic primitives.</p>
2916
2917<p>Use this option to annotate or decorate an image with one or more graphic
2918primitives. The primitives include shapes, text, transformations, and pixel
2919operations.</p>
2920
2921<p>The shape primitives:</p>
2922
2923<dl class="dl-horizontal">
2924<dt>point</dt><dd> x,y</dd>
2925<dt>line</dt><dd> x0,y0 x1,y1</dd>
2926<dt>rectangle</dt><dd> x0,y0 x1,y1</dd>
2927<dt>roundRectangle</dt><dd> x0,y0 x1,y1 wc,hc</dd>
2928<dt>arc</dt><dd> x0,y0 x1,y1 a0,a1</dd>
2929<dt>ellipse</dt><dd> x0,y0 rx,ry a0,a1</dd>
2930<dt>circle</dt><dd> x0,y0 x1,y1</dd>
2931<dt>polyline</dt><dd> x0,y0 ... xn,yn</dd>
2932<dt>polygon</dt><dd> x0,y0 ... xn,yn</dd>
2933<dt>bezier</dt><dd> x0,y0 ... xn,yn</dd>
2934<dt>path</dt><dd>specification </dd>
2935<dt>image</dt><dd> operator x0,y0 w,h filename</dd>
2936</dl>
2937
2938<p>The text primitive:</p>
2939
2940<dl class="dl-horizontal">
2941<dt>text</dt><dd>x0,y0 string</dd>
2942</dl>
2943<p>The text gravity primitive:</p>
2944
2945<dl class="dl-horizontal">
2946<dt>gravity</dt><dd>NorthWest, North, NorthEast, West, Center, East, SouthWest, South, or SouthEast</dd>
2947</dl>
2948
2949<p>The text gravity primitive only affects the placement of text and does not
2950interact with the other primitives. It is equivalent to using the <a href="command-line-options.html#gravity">-gravity</a> command-line option, except that it is limited in
2951scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
2952
2953<p>The transformation primitives:</p>
2954
2955<dl class="dl-horizontal">
2956<dt>rotate</dt><dd>degrees</dd>
2957<dt>translate</dt><dd>dx,dy</dd>
2958<dt>scale</dt><dd>sx,sy</dd>
2959<dt>skewX</dt><dd>degrees</dd>
2960<dt>skewY</dt><dd>degrees</dd>
2961</dl>
2962
2963<p>The pixel operation primitives:</p>
2964
2965<dl class="dl-horizontal">
2966<dt>color</dt><dd>x0,y0 method</dd>
2967<dt>matte</dt><dd>x0,y0 method</dd>
2968</dl>
2969
2970<p>The shape primitives are drawn in the color specified by the preceding <a href="command-line-options.html#fill">-fill</a> setting. For unfilled shapes, use <a href="command-line-options.html#fill">-fill none</a>. You can optionally control the stroke (the
2971"outline" of a shape) with the <a href="command-line-options.html#stroke">-stroke</a> and <a href="command-line-options.html#strokewidth">-strokewidth</a> settings.</p>
2972
2973<p>A <code>point</code> primitive is specified by a single <var>point</var> in the
2974pixel plane, that is, by an ordered pair of integer coordinates,
2975<var>x</var>,<var>y</var>. (As it involves only a single pixel, a <code>point</code>
2976primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
2977
2978<p>A <code>line</code> primitive requires a start point and end point.</p>
2979
2980<p>A <code>rectangle</code> primitive is specified by the pair of points at the
2981upper left and lower right corners.</p>
2982
2983<p>A <code>roundRectangle</code> primitive takes the same corner points as
2984a <code>rectangle</code> followed by the width and height of the rounded corners
2985to be removed.</p>
2986
2987<p>The <code>circle</code> primitive makes a disk (filled) or circle (unfilled).
2988Give the center and any point on the perimeter (boundary).</p>
2989
2990<p>The <code>arc</code> primitive is used to inscribe an elliptical segment in
2991to a given rectangle. An <code>arc</code> requires the two corners used for
2992<code>rectangle</code> (see above) followed by the start and end angles of the
2993arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
2994points produced are then joined with a line segment and the resulting segment
2995of an ellipse is filled.</p>
2996
2997<p>Use <code>ellipse</code> to draw a partial (or whole) ellipse. Give the
2998center point, the horizontal and vertical "radii" (the <var>semi-axes</var> of
2999the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
30000,360).</p>
3001
3002<p>The <code>polyline</code> and <code>polygon</code> primitives require three or
3003more points to define their perimeters. A <code>polyline</code> is simply
3004a <code>polygon</code> in which the final point is not stroked to the start
3005point. When unfilled, this is a <var>polygonal line</var>. If the <a href="command-line-options.html#stroke">-stroke</a> setting is <code>none</code> (the default), then
3006a <code>polyline</code> is identical to a <code>polygon</code>. </p>
3007
3008<p>A <var>coordinate</var> is a pair of integers separated by a space or
3009optional comma. </p>
3010
3011<p>As an example, to define a circle centered at 100,100 that extends to
3012150,150 use:</p>
3013
3014<pre>
3015-draw 'circle 100,100 150,150'
3016</pre>
3017
3018<p>The <code>Bezier</code> primitive creates a spline curve and requires three
3019or points to define its shape. The first and last points are the
3020<var>knots</var> and these points are attained by the curve, while any
3021intermediate coordinates are <var>control points</var>. If two control points
3022are specified, the line between each end knot and its sequentially respective
3023control point determines the tangent direction of the curve at that end. If
3024one control point is specified, the lines from the end knots to the one
3025control point determines the tangent directions of the curve at each end. If
3026more than two control points are specified, then the additional control points
3027act in combination to determine the intermediate shape of the curve. In order
3028to draw complex curves, it is highly recommended either to use the
3029<code>path</code> primitive or to draw multiple four-point bezier segments with
3030the start and end knots of each successive segment repeated. For example:</p>
3031
3032<pre>
3033-draw 'bezier 20,50 45,100 45,0 70,50'
3034-draw 'bezier 70,50 95,100 95,0 120,50'
3035</pre>
3036
3037<p>A <code>path</code> represents an outline of an object, defined in terms of
3038moveto (set a new current point), lineto (draw a straight line), curveto (draw
3039a Bezier curve), arc (elliptical or circular arc) and closepath (close the
3040current shape by drawing a line to the last moveto) elements. Compound paths
3041(i.e., a path with subpaths, each consisting of a single moveto followed by
3042one or more line or curve operations) are possible to allow effects such as
3043<var>donut holes</var> in objects. (See <a href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
3044
3045<p>Use <code>image</code> to composite an image with another image. Follow the
3046image keyword with the composite operator, image location, image size, and
3047filename:</p>
3048
3049<pre>
3050-draw 'image SrcOver 100,100 225,225 image.jpg'
3051</pre>
3052
3053<p>You can use 0,0 for the image size, which means to use the actual
3054dimensions found in the image header. Otherwise, it is scaled to the given
3055dimensions. See <a href="compose.html">Alpha Compositing</a> for
3056a detailed discussion of alpha composition methods that are available. </p>
3057
3058<p>The "special augmented compose operators" such as "dissolve" that require
3059arguments cannot be used at present with the <code>-draw image</code> option.
3060 </p>
3061
3062<p>Use <code>text</code> to annotate an image with text. Follow the text
3063coordinates with a string. If the string has embedded spaces, enclose it in
3064single or double quotes.</p>
3065
3066<p>For example, the following annotates the image with <code>Works like
3067magick!</code> for an image titled <code>bird.miff</code>. </p>
3068
3069<pre>
3070-draw "text 100,100 'Works like magick!' "
3071</pre>
3072
3073<p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
3074to annotate an image with text.</p>
3075
3076<p>The <code>rotate</code> primitive rotates subsequent shape primitives and
3077text primitives about the origin of the main image. If the <a href="command-line-options.html#region">-region</a> option precedes the <a href="command-line-options.html#draw">-draw</a>
3078option, the origin for transformations is the upper left corner of the
3079region.</p>
3080
3081<p>The <code>translate</code> primitive translates subsequent shape and text
3082primitives.</p>
3083
3084<p>The <code>scale</code> primitive scales them.</p>
3085
3086<p>The <code>skewX</code> and <code>skewY</code> primitives skew them with respect
3087to the origin of the main image or the region.</p>
3088
3089<p>The transformations modify the current affine matrix, which is initialized
3090from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
3091option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
3092option. The initial affine matrix is not affected; that matrix is only changed
3093by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
3094<a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
3095reinitialized from the initial affine matrix.</p>
3096
3097<p>Use the <code>color</code> primitive to change the color of a pixel to the
3098fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
3099a method:</p>
3100
3101<pre>
3102point
3103replace
3104floodfill
3105filltoborder
3106reset
3107</pre>
3108
3109<p>Consider the target pixel as that specified by your coordinate. The
3110<code>point</code> method recolors the target pixel. The <code>replace</code>
3111method recolors any pixel that matches the color of the target pixel.
3112<code>Floodfill</code> recolors any pixel that matches the color of the target
3113pixel and is a neighbor, whereas <code>filltoborder</code> recolors any neighbor
3114pixel that is not the border color. Finally, <code>reset</code> recolors all
3115pixels.</p>
3116
3117<p>Use <code>matte</code> to the change the pixel matte value to transparent.
3118Follow the pixel coordinate with a method (see the <code>color</code> primitive
3119for a description of methods). The <code>point</code> method changes the matte
3120value of the target pixel. The <code>replace</code> method changes the matte
3121value of any pixel that matches the color of the target pixel.
3122<code>Floodfill</code> changes the matte value of any pixel that matches the
3123color of the target pixel and is a neighbor, whereas <code>filltoborder</code>
3124changes the matte value of any neighbor pixel that is not the border color (<a href="command-line-options.html#bordercolor">-bordercolor</a>). Finally <code>reset</code> changes the
3125matte value of all pixels.</p>
3126
3127<p>You can set the primitive color, font, and font bounding box color with <a href="command-line-options.html#fill">-fill</a>, <a href="command-line-options.html#font">-font</a>, and <a href="command-line-options.html#box">-box</a>
3128respectively. Options are processed in command line order so be sure to use
3129these options <var>before</var> the <a href="command-line-options.html#draw">-draw</a> option.</p>
3130
3131<p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
3132than 1.png).</p>
3133
3134<p>Drawing primitives conform to the <a href="magick-vector-graphics.html">Magick
3135Vector Graphics</a> format.</p>
3136
3137
3138<div style="margin: auto;">
3139 <h3 class="magick-header"><a id="duplicate"></a>-duplicate <var>count,indexes</var></h3>
3140</div>
3141
3142<p class="magick-description">duplicate an image one or more times.</p>
3143
3144<p>Specify the count and the image to duplicate by its index in the sequence.
3145The first image is index 0. Negative indexes are relative to the end of the
3146sequence, for example, -1 represents the last image of the sequence. Specify
3147a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g.
31480,2). Use <code>+duplicate</code> to duplicate the last image in the current
3149image sequence.</p>
3150
3151<div style="margin: auto;">
3152 <h3 class="magick-header"><a id="edge"></a>-edge <var>radius</var></h3>
3153</div>
3154
3155<p class="magick-description">detect edges within an image.</p>
3156
3157<div style="margin: auto;">
3158 <h3 class="magick-header"><a id="emboss"></a>-emboss <var>radius</var></h3>
3159</div>
3160
3161<p class="magick-description">emboss an image.</p>
3162
3163<div style="margin: auto;">
3164 <h3 class="magick-header"><a id="encipher"></a>-encipher <var>filename</var></h3>
3165</div>
3166
3167<p class="magick-description">Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</p>
3168
3169<p>Get the passphrase from the file specified by <var>filename</var>.</p>
3170
3171<p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or
3172Decipher an Image</a>.</p>
3173
3174
3175
3176<div style="margin: auto;">
3177 <h3 class="magick-header"><a id="encoding"></a>-encoding <var>type</var></h3>
3178</div>
3179
3180<p class="magick-description">specify the text encoding.</p>
3181
3182<p>Choose from</p>
3183
3184<pre>
3185AdobeCustom AdobeExpert
3186AdobeStandard AppleRoman
3187BIG5 GB2312
3188Latin 2 None
3189SJIScode Symbol
3190Unicode Wansung
3191</pre>
3192
3193<div style="margin: auto;">
3194 <h3 class="magick-header"><a id="endian"></a>-endian <var>type</var></h3>
3195</div>
3196
3197<p class="magick-description">Specify endianness (<code>MSB</code> or <code>LSB</code>) of the image.</p>
3198
3199<p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3200
3201<p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3202
3203
3204<div style="margin: auto;">
3205 <h3 class="magick-header"><a id="enhance"></a>-enhance</h3>
3206</div>
3207
3208<p class="magick-description">Apply a digital filter to enhance a noisy image.</p>
3209
3210
3211<div style="margin: auto;">
3212 <h3 class="magick-header"><a id="equalize"></a>-equalize</h3>
3213</div>
3214
3215<p class="magick-description">perform histogram equalization on the image channel-by-channel.</p>
3216
3217<p>To perform histogram equalization on all channels in concert, transform the
3218image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3219equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3220
3221<p>For example using HSL, we have: ... <code>-colorspace HSL -channel lightness
3222-equalize -colorspace RGB</code> ...</p>
3223
3224<p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3225components transformation that puts most of the information in the first
3226channel. Here we have ... <code>-colorspace OHTA -channel red -equalize
3227-colorspace RGB</code> ...</p>
3228
3229<div style="margin: auto;">
3230 <h3 class="magick-header"><a id="evaluate"></a>-evaluate <var>operator value</var></h3>
3231</div>
3232
3233<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</p>
3234
3235<p>(See the <a href="command-line-options.html#function">-function</a> operator for some
3236multi-parameter functions. See the <a href="command-line-options.html#fx">-fx</a> operator if more
3237elaborate calculations are needed.)</p>
3238
3239<p>The behaviors of each <var>operator</var> are summarized in the
3240following list. For brevity, the numerical value of a "pixel" referred to
3241below is the value of the corresponding channel of that pixel, while
3242a "normalized pixel" is that number divided by the maximum
3243(installation-dependent) value <var>QuantumRange</var>. (If
3244normalized pixels are used, they are restored, following the other
3245calculations, to the full range by multiplying by <var>QuantumRange</var>.)</p>
3246
3247<table class="table table-condensed table-striped">
3248 <col width="25%">
3249 <col width="75%">
3250 <thead>
3251 <tr>
3252 <th><var>operator</var></th>
3253 <th>Summary (see further below for details)</th>
3254 </tr>
3255 </thead>
3256 <tbody>
3257
3258 <tr><td>Abs </td> <td>Add <var>value</var> to pixels and return absolute value. </td></tr>
3259 <tr><td>Add </td> <td>Add <var>value</var> to pixels. </td></tr>
3260 <tr><td>AddModulus </td> <td>Add <var>value</var> to pixels modulo <var>QuantumRange</var>.</td></tr>
3261 <tr><td>And </td> <td>Binary AND of pixels with <var>value</var>.</td></tr>
3262 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3263 <tr><td>Divide </td> <td>Divide pixels by <var>value</var>.</td></tr>
3264 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
3265 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
3266 <tr><td>LeftShift </td> <td>Shift the pixel values left by <var>value</var> bits (i.e., multiply pixels by 2<sup><var>value</var></sup>).</td></tr>
3267 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
3268 <tr><td>Max </td> <td>Set pixels to maximum of <var>value</var> and current pixel <var>value</var> (i.e. set any pixels currently less than <var>value</var> to <var>value</var>).</td></tr>
3269 <tr><td>Mean </td> <td>Add the <var>value</var> and divide by 2.</td></tr>
3270 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
3271 <tr><td>Min </td> <td>Set pixels to minimum of <var>value</var> and current pixel <var>value</var> (i.e. set any pixels currently greater than <var>value</var> to <var>value</var>).</td></tr>
3272 <tr><td>Multiply </td> <td>Multiply pixels by <var>value</var>.</td></tr>
3273 <tr><td>Or </td> <td>Binary OR of pixels with <var>value</var>.</td></tr>
3274 <tr><td>Pow </td> <td>Raise normalized pixels to the power <var>value</var>.</td></tr>
3275 <tr><td>RightShift </td> <td>Shift the pixel values right by <var>value</var> bits (i.e., divide pixels by 2<sup><var>value</var></sup>).</td></tr>
3276 <tr><td>RMS</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3277 <tr><td>RootMeanSquare</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3278 <tr><td>Set </td> <td>Set pixel equal to <var>value</var>.</td></tr>
3279 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3280 <tr><td>Subtract </td> <td>Subtract <var>value</var> from pixels.</td></tr>
3281 <tr><td>Xor </td> <td>Binary XOR of pixels with <var>value.</var></td></tr>
3282
3283 <tr><td> </td><td> </td></tr>
3284
3285 <tr><td>Gaussian-noise</td><td> </td></tr>
3286 <tr><td>Impulse-noise</td><td> </td></tr>
3287 <tr><td>Laplacian-noise</td><td> </td></tr>
3288 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise">-noise</a> operators.)</td></tr>
3289 <tr><td>PoissonNoise</td><td> </td></tr>
3290 <tr><td>Uniform-noise</td><td> </td></tr>
3291
3292 <tr><td> </td><td> </td></tr>
3293
3294 <tr><td>Threshold </td> <td>Threshold pixels larger than <var>value</var>.</td></tr>
3295 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <var>value</var>.</td></tr>
3296 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <var>value</var>. </td></tr>
3297 </tbody>
3298 </table>
3299
3300<p>The specified functions are applied only to each previously set <a href="command-line-options.html#channel">-channel</a> in the image. If necessary, the results of the
3301calculations are truncated (clipped) to fit in the interval [0, <var>QuantumRange</var>]. The transparency channel of the image is
3302represented as a 'alpha' values (0 = fully transparent), so, for example, a
3303<code>Divide</code> by 2 of the alpha channel will make the image
3304semi-transparent. Append the percent symbol '<code>%</code>' to specify a value
3305as a percentage of the <var>QuantumRange</var>.</p>
3306
3307<p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3308<a href="command-line-options.html#list">-list evaluate</a>.</p>
3309
3310<p>The results of the <code>Add</code>, <code>Subtract</code> and
3311<code>Multiply</code> methods can also be achieved using either the <a href="command-line-options.html#level">-level</a> or the <a href="command-line-options.html#level">+level</a> operator, with
3312appropriate argument, to linearly modify the overall range of color values.
3313Please note, however, that <a href="command-line-options.html#level">-level</a> treats transparency as
3314'matte' values (0 = opaque), while <a href="command-line-options.html#level">-evaluate</a> works with
3315'alpha' values.</p>
3316
3317<p><code>AddModulus</code> has been added as of ImageMagick 6.4.8-4 and provides
3318addition modulo the <var>QuantumRange</var>. It is therefore
3319equivalent to <code>Add</code> unless the resulting pixel value is outside the
3320interval [0, <var>QuantumRange</var>]. </p>
3321
3322<p><code>Exp or Exponential</code> has been added as of ImageMagick 6.6.5-1 and
3323works on normalized pixel values. The <var>value</var> used with
3324<code>Exp</code> should be negative so as to produce a decaying exponential
3325function. Non-negative values will always produce results larger unity and
3326thus outside the interval [0, <var>QuantumRange</var>]. The
3327formula is expressed below. </p>
3328
3329<p class="text-center">
3330exp(<var>value</var> × <b><var>u</var></b>)
3331</p>
3332
3333<p> If the input image is squared, for example, using <a href="command-line-options.html#-function">-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be
3334the result.</p>
3335
3336<p><code>Log</code> has been added as of ImageMagick 6.4.2-1 and works on
3337normalized pixel values. This a <var>scaled</var> log function. The <var>value</var> used with <code>Log</code> provides a <var>scaling
3338factor</var> that adjusts the curvature in the graph of the log function. The
3339formula applied to a normalized value <b><var>u</var></b> is below. </p>
3340
3341<p class="text-center">
3342log(<var>value</var> × <b><var>u</var></b> + 1) / log(<var>value</var> + 1)
3343</p>
3344
3345<p><code>Pow</code> has been added as of ImageMagick 6.4.1-9, and works on
3346normalized pixel values. Note that <code>Pow</code> is related to the <a href="command-line-options.html#gamma">-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent
3347to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3348with <a href="command-line-options.html#gamma">-gamma</a> is simply the reciprocal of the value used
3349with <code>Pow</code>.</p>
3350
3351<p><code>Cosine</code> and <code>Sine</code> was added as of IM v6.4.8-8 and
3352converts the image values into a value according to a (co)sine wave function.
3353The synonyms <code>Cos</code> and <code>Sin</code> may also be used. The output
3354is biased 50% and normalized by 50% so as to fit in the respective color value
3355range. The <var>value</var> scaling of the <var>period</var> of the
3356function (its frequency), and thus determines the number of 'waves' that will
3357be generated over the input color range. For example, if the <var>value</var> is 1, the effective period is simply the <var>QuantumRange</var>; but if the <var>value</var> is 2,
3358then the effective period is the <var>half</var> the <var>QuantumRange</var>.</p>
3359
3360<p class="text-center">
33610.5 + 0.5 × cos(2 π <b><var>u</var></b> × <var>value</var>).
3362</p>
3363
3364<p>See also the <a href="command-line-options.html#function">-function</a> operator, which is a
3365multi-value version of evaluate. </p>
3366
3367<div style="margin: auto;">
3368 <h3 class="magick-header"><a id="evaluate-sequence"></a>-evaluate-sequence <var>operator</var></h3>
3369</div>
3370
3371<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or
3372logical expression over a sequence of images.</p>
3373
3374<p>To print a complete list of <a href="command-line-options.html#evaluate-sequence">-evaluate-sequence</a> operators, use <a href="command-line-options.html#list">-list evaluate</a>.</p>
3375
3376<div style="margin: auto;">
3377 <h3 class="magick-header"><a id="extent"></a>-extent <var>geometry</var></h3>
3378</div>
3379
3380<p class="magick-description">Set the image size and offset.</p>
3381
3382<p>If the image is enlarged, unfilled areas are set to the background color.
3383To position the image, use offsets in the <var>geometry</var>
3384specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting. To
3385specify how to compose the image with the background, use <a href="command-line-options.html#compose">-compose</a>.</p>
3386
3387<p>This command reduces or expands a JPEG image to fit on an 800x600
3388display. If the aspect ratio of the input image isn't exactly 4:3, then the
3389image is centered on an 800x600 black canvas: </p>
3390
3391<pre>
3392convert input.jpg -resize 800x600 -background black -compose Copy \
3393 -gravity center -extent 800x600 -quality 92 output.jpg
3394</pre>
3395
3396<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3397
3398<div style="margin: auto;">
3399 <h3 class="magick-header"><a id="extract"></a>-extract <var>geometry</var></h3>
3400</div>
3401
3402<p class="magick-description">Extract the specified area from image.</p>
3403
3404<p>This option is most useful for extracting a subregion of a very large raw
3405image. Note that these two commands are equivalent:</p>
3406
3407<pre>
3408convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \
3409 image.rgb image.png",
3410convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \
3411 image.rgb image.png"
3412</pre>
3413
3414<p>If you omit the offsets, as in</p>
3415
3416<pre>
3417convert -size 16000x16000 -depth 8 -extract 640x480 \
3418 image.rgb image.png
3419</pre>
3420
3421<p>the image is <var>resized</var> to the specified dimensions instead,
3422equivalent to:</p>
3423
3424<pre>
3425convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png
3426</pre>
3427
3428<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3429
3430<div style="margin: auto;">
3431 <h3 class="magick-header"><a id="family"></a>-family <var>fontFamily</var></h3>
3432</div>
3433
3434<p class="magick-description">Set a font family for text.</p>
3435
3436<p>This setting suggests a font family that ImageMagick should try to use for
3437rendering text. If the family can be found it is used; if not, a default font
3438(e.g., "Arial") or a family known to be similar is substituted (e.g.,
3439"Courier" might be used if "System" is requested but not found). </p>
3440
3441<p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3442
3443<div style="margin: auto;">
3444 <h3 class="magick-header"><a id="features"></a>-features <var>distance</var></h3>
3445</div>
3446
3447<p class="magick-description">display (cooccurrence matrix) texture measure features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance.</p>
3448
3449<pre>
3450Angular Second Moment Sum Entropy
3451Contrast Entropy
3452Correlation Difference Variance
3453Sum of Squares Variance Difference Entropy
3454Inverse Difference Moment Information Measure of Correlation 1
3455Sum Average Information Measure of Correlation 2
3456Sum Variance Maximum Correlation Coefficient
3457</pre>
3458
3459<div style="margin: auto;">
3460 <h3 class="magick-header"><a id="fft"></a>-fft</h3>
3461</div>
3462
3463<p class="magick-description">implements the forward discrete Fourier transform (DFT).</p>
3464
3465<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3466users in ImageMagick 6.6.0-9). It transforms an image from the normal
3467(spatial) domain to the frequency domain. In the frequency domain, an image is
3468represented as a superposition of complex sinusoidal waves of varying
3469amplitudes. The image x and y coordinates are the possible frequencies along
3470the x and y directions, respectively, and the pixel intensity values are
3471complex numbers that correspond to the sinusoidal wave amplitudes. See for
3472example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3473Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3474Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3475Transform</a>.</p>
3476
3477<p>A single image name is provided as output for this option. However, the
3478output result will have two components. It is either a two-frame image or two
3479separate images, depending upon whether the image format specified supports
3480multi-frame images. The reason that we get a dual output result is because the
3481frequency domain represents an image using complex numbers, which cannot be
3482visualized directly. Therefore, the complex values are automagically separated
3483into a two-component image representation. The first component is the
3484magnitude of the complex number and the second is the phase of the complex
3485number. See for example, <a href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3486
3487<p>The magnitude and phase component images must be specified using image
3488formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3489PFM, EXR and PNG are the recommended image formats to use. All of these
3490formats, except PNG support multi-frame images. So for example,</p>
3491
3492<pre>
3493convert image.png -fft fft_image.miff
3494</pre>
3495
3496<p>generates a magnitude image as <code>fft_image.miff[0]</code> and a phase
3497image as <code>fft_image.miff[1]</code>. Similarly,</p>
3498
3499<pre>
3500convert image.png -fft fft_image.png
3501</pre>
3502
3503<p>generates a magnitude image as <code>fft_image-0.png</code> and a phase image
3504as <code>fft_image-1.png</code>. If you prefer this representation, then you can
3505force any of the other formats to produce two output images by including <a href="command-line-options.html#adjoin">+adjoin</a> following -fft in the command line.</p>
3506
3507<p>The input image can be any size, but if not square and even-dimensioned, it
3508is padded automagically to the larger of the width or height of the input
3509image and to an even number of pixels. The padding will occur at the bottom
3510and/or right sides of the input image. The resulting output magnitude and
3511phase images is square at this size. The kind of padding relies on the <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting.</p>
3512
3513<p>Both output components will have dynamic ranges that fit within
3514[0, <var>QuantumRange</var>], so that HDRI need not be enabled.
3515Phase values nominally range from 0 to 2*π, but is scaled to span the full
3516dynamic range. (The first few releases had non-HDRI scaled but HDRI not
3517scaled). The magnitude image is not scaled and thus generally will contain
3518very small values. As such, the image normally will appear totally black. In
3519order to view any detail, the magnitude image typically is enhanced with a log
3520function into what is usually called the spectrum. A log function is used to
3521enhance the darker values more in comparison to the lighter values. This can
3522be done, for example, as follows:</p>
3523
3524<pre>
3525convert fft_image.miff[0] -contrast-stretch 0 \
3526 -evaluate log 1000 fft_image_spectrum.png"
3527</pre>
3528
3529<p>where either <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> 0 or <a href="command-line-options.html#auto-level">-auto-level</a> is used to scale the image to full dynamic
3530range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3531typically is specified between 100 and 10,000, depending upon the amount of
3532detail that one wants to bring out in the spectrum. Larger values produce more
3533visible detail. Too much detail, however, may hide the important features.</p>
3534
3535<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3536use <a href="command-line-options.html#fft">-fft</a>.</p>
3537
3538<p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3539and imaginary components of the complex valued Fourier transform.</p>
3540
3541<p>However, as the real and imaginary components can contain negative values,
3542this requires that IM be configured with HDRI enabled. In this case, you must
3543use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3544results, since they are formats that preserve both negative and fractional
3545values without clipping them or truncating the fractional part. With either
3546MIFF or TIF, one should add -define quantum:format=32, to allow those image
3547types to work properly in HDRI mode without clipping.</p>
3548
3549<p>The real and imaginary component images resulting from <a href="command-line-options.html#fft">+fft</a> are also square, even dimensioned images due to the same
3550padding that was discussed above for the magnitude and phase component
3551images.</p>
3552
3553<p>See the discussion on HDRI implementations of ImageMagick on the page <a href="high-dynamic-range.html">High Dynamic-Range Images</a>. For more
3554about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages, <a href="http://www.fmwconcepts.com/imagemagick/fourier_transforms/fourier.html">Fred's Fourier Processing With ImageMagick page</a> or this <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
3555 entry. </p>
3556
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]3557<p>By default the FFT is normalized (and the IFT is not). Use "<code><a href="command-line-options.html#define">-define</a> fourier:normalize=forward</code> to explicitly normalize the FFT and unnormalize the IFT.</p>
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]3558
3559
3560<div style="margin: auto;">
3561 <h3 class="magick-header"><a id="fill"></a>-fill <var>color</var></h3>
3562</div>
3563
3564<p class="magick-description">color to use when filling a graphic primitive.</p>
3565
3566<p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3567HSL, HSLA, CMYK, or CMYKA specification. See <a href="color.html">Color Names</a> for
3568a description of how to properly specify the color argument.</p>
3569
3570<p>Enclose the color specification in quotation marks to prevent the "#" or
3571the parentheses from being interpreted by your shell.</p>
3572
3573<p>For example,</p>
3574
3575<pre>
3576-fill blue
3577-fill "#ddddff"
3578-fill "rgb(255,255,255)"
3579</pre>
3580
3581<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3582
3583<p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3584
3585<div style="margin: auto;">
3586 <h3 class="magick-header"><a id="filter"></a>-filter <var>type</var></h3>
3587</div>
3588
3589<p class="magick-description">Use this <var>type</var> of filter when resizing or distorting an image.</p>
3590
3591<p>Use this option to affect the resizing operation of an image during
3592operations such as <a href="command-line-options.html#resize">-resize</a> and <a href="command-line-options.html#distort">-distort</a>. For example you can use a simple resize filter such as:</p>
3593
3594<pre>
3595Point Hermite Cubic
3596Box Gaussian Catrom
3597Triangle Quadratic Mitchell
3598</pre>
3599
3600<p>The <code>Bessel</code> and <code>Sinc</code> filter is also provided (as well
3601as a faster <code>SincFast</code> equivalent form). However these filters are
3602generally useless on their own as they are infinite filters that are being
3603clipped to the filters support size. Their direct use is not recommended
3604except via expert settings (see below). </p>
3605
3606<p>Instead these special filter functions are typically windowed by a windowing
3607function that the <a href="command-line-options.html#filter">-filter</a> setting defines. That is
3608using these functions will define a 'Windowed' filter, appropriate to the
3609operator involved. Windowed filters include: </p>
3610
3611<pre>
3612Lanczos Hamming Parzen
3613Blackman Kaiser Welsh
3614Hanning Bartlett Bohman
3615</pre>
3616
3617<p>Also one special self-windowing filter is also provided
3618<code>Lagrange</code>, which will automagically re-adjust its function depending
3619on the current 'support' or 'lobes' expert settings (see below).</p>
3620
3621<p>If you do not select a filter with this option, the filter defaults to
3622<code>Mitchell</code> for a colormapped image, an image with a matte channel, or
3623if the image is enlarged. Otherwise the filter default to
3624<code>Lanczos</code>.</p>
3625
3626<p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3627filter</a> option.</p>
3628
3629<p>You can modify how the filter behaves as it scales your image through the
3630use of these expert settings (see also <a href="command-line-options.html#define">-define</a> and <a href="command-line-options.html#set">-set</a>):-</p>
3631
3632<table class="table table-condensed table-striped">
3633 <tr>
3634 <td>-define filter:blur=<var>factor</var></td>
3635 <td>Scale the X axis of the filter (and its window). Use &gt; 1.0 for
3636 blurry or &lt; 1.0 for sharp. This should only be used with Gaussian and
3637 Gaussian-like filters simple filters, or you may not get the expected
3638 results. </td>
3639 </tr>
3640
3641 <tr>
3642 <td>-define filter:support=<var>radius</var></td>
3643 <td>Set the filter support radius. Defines how large the filter should be and
3644 thus directly defines how slow the filtered resampling process is. All
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]3645 filters have a default 'preferred' support size. Some filters like
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]3646 <code>Lagrange</code> and windowed filters adjust themselves depending on
3647 this value. With simple filters this value either does nothing (but slow
3648 the resampling), or will clip the filter function in a detrimental way.
3649 </td>
3650 </tr>
3651
3652 <tr>
3653 <td>-define filter:lobes=<var>count</var></td>
3654 <td>Set the number of lobes to use for the Sinc/Bessel filter. This an
3655 alternative way of specifying the 'support' range of the filter, that is
3656 designed to be more suited to windowed filters, especially when used for
3657 image distorts.</td>
3658 </tr>
3659
3660 <tr>
3661 <td>-define filter:sigma=<var>value</var></td>
3662 <td>The 'sigma' value used to define the <code>Gaussian</code> filter. Default
3663 sigma value is '<code>0.5</code>'. It only effects <code>Gaussian</code> but
3664 does not shrink (but may enlarge) the filter's 'support'. It can be used
3665 to generate very small blurs but without the filter 'missing' pixels due
3666 to using a small support setting. A larger value of '<code>0.707</code>'
3667 (a value of '1/sqrt(2)') is another common setting. </td>
3668 </tr>
3669
3670 <tr>
3671 <td>-define filter:b=<var>b-spline_factor</var></td>
3672 </tr><tr>
3673 <td>-define filter:c=<var>keys_alpha_factor</var></td>
3674 <td>Redefine the values used for cubic filters such as <code>Cubic</code>,
3675 <code>Catrom</code>, <code>Mitchel</code>, and <code>Hermite</code>, as well as
3676 the <code>Parzen</code> cubic windowing function. If only one of the values
3677 are defined, the other is set so as to generate a 'Cubic-Keys' filter.
3678 The values meaning was defined by a research paper by
3679 Mitchell-Netravali.</td>
3680 </tr>
3681
3682 <tr>
3683 <td>-define filter:kaiser-beta=<var>value</var></td>
3684 <td>The 'alpha' value used to as part of the Kaiser Windowing function.
3685 Default value is '6.5'. It only effects Kaiser windowing function, and
3686 does not effect any other attributes.
3687 Before ImageMagick v6.7.6-10, this option was known as "filter:alpha", (an
3688 inheritance from the very old "zoom" program). It was changed to bring the
3689 function in line with more modern academic research usage, and better
3690 assign it be more definitive. </td>
3691 </tr>
3692
3693 <tr>
3694 <td>-define filter:kaiser-alpha=<var>value</var></td>
3695 <td>This value when multiplied by 'PI' is equivalent to "kaiser-beta", and
3696 will override that setting. It only effects Kaiser windowing function,
3697 and does not effect any other attributes. </td>
3698 </tr>
3699
3700 <tr>
3701 <td>-define filter:filter=<var>filter_function</var></td>
3702 <td>Use this function directly as the weighting filter. This will allow
3703 you to directly use a windowing function such as <code>Blackman</code>,
3704 as a resampling filter, rather than as its normal usage as a windowing
3705 function. If defined, no windowing function also defined, the window function is set
3706 to <code>Box</code>). Directly specifying <code>Sinc</code> or <code>Jinc</code>
3707 as a filter will also do this. </td>
3708 </tr>
3709
3710 <tr>
3711 <td>-define filter:window=<var>filter_function</var></td>
3712 <td>The IIR (infinite impulse response) filters <code>Sinc</code> and
3713 <code>Jinc</code> are windowed (brought down to zero over the defined
3714 support range) with the given filter. This allows you to specify a filter
3715 function to be used as a windowing function for these IIR filters.
3716 Many of the defined filters are actually windowing functions for these IIR
3717 filters. A typical choices is <code>Box</code>, (which effectively turns
3718 off the windowing function). </td>
3719 </tr>
3720
3721 <tr>
3722 <td>-define filter:win-support=<var>radius</var></td>
3723 <td>Scale windowing function to this size instead. This causes the windowing
3724 (or self-windowing Lagrange filter) to act is if the support window is
3725 larger than what is actually supplied to the calling operator. The filter
3726 however is still clipped to the real support size given. If unset this
3727 will equal the normal filter support size. </td>
3728 </tr>
3729
3730 <tr>
3731 <td>-define filter:verbose=<var>1</var></td>
3732 <td>This causes IM to print information on the final internal filter
3733 selection to standard output. This includes a commented header on the
3734 filter settings being used, and data allowing the filter weights to be
3735 easily graphed. Note however that some filters are internally defined in terms of other filters. The <code>Lanczos</code> filter for example is defined in terms of
3736 a <code>SincFast</code> windowed <code>SincFast</code> filter, while
3737 <code>Mitchell</code> is defined as a general <code>Cubic</code> family filter
3738 with specific 'B' and 'C' settings. </td>
3739 </tr>
3740
3741</table>
3742
3743<p>For example, to get a 8 lobe jinc windowed sinc filter (Genseng filter?):</p>
3744
3745<pre>
3746convert image.png \
3747 -filter sinc \
3748 -set filter:window=jinc \
3749 -set filter:lobes=8 \
3750 -resize 150% image.jpg"
3751</pre>
3752
3753<p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
3754
3755<pre>
3756convert image.png \
3757 -set filter:filter=sinc \
3758 -set filter:lobes=4 \
3759 -resize 150% image.jpg"
3760</pre>
3761
3762<p>To extract the data for a raw windowing function, combine it with
3763a '<code>Box</code>' filter. For example the '<code>Welch</code> parabolic
3764windowing function. </p>
3765
3766<pre>
3767convert null: -define filter:filter=Box \
3768 -define filter:window=Welch \
3769 -define filter:support=1.0 \
3770 -define filter:verbose=1 \
3771 -resize 2 null: &gt; window_welch.dat
3772gnuplot
3773 set grid
3774 plot \"window_welch.dat\" with lines
3775</pre>
3776
3777<p>Note that the use of expert options is provided for image processing experts
3778who have studied and understand how resize filters work. Without this
3779knowledge, and an understanding of the definition of the actual filters
3780involved, using expert settings are more likely to be detrimental to your image
3781resizing.</p>
3782
3783
3784<div style="margin: auto;">
3785 <h3 class="magick-header"><a id="flatten"></a>-flatten</h3>
3786</div>
3787
3788<p class="magick-description">This is a simple alias for the <a href="command-line-options.html#layers">-layers</a> method "flatten".</p>
3789
3790
3791<div style="margin: auto;">
3792 <h3 class="magick-header"><a id="flip"></a>-flip</h3>
3793</div>
3794
3795<p class="magick-description">create a <var>mirror image</var></p>
3796
3797<p>reflect the scanlines in the vertical direction. The image will be mirrored
3798upside-down. </p>
3799
3800
3801<div style="margin: auto;">
3802 <h3 class="magick-header"><a id="floodfill"></a>-floodfill {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var> <var>color</var></h3>
3803</div>
3804
3805<p class="magick-description">floodfill the image with color at the specified offset.</p>
3806
3807<p>Flood fill starts from the given 'seed point' which is not gravity effected.
3808Any color that matches within <a href="command-line-options.html#fuzz">-fuzz</a> color distance of the
3809given <var>color</var> argument, connected to that 'seed point'
3810will be replaced with the current <a href="command-line-options.html#fill">-fill</a> color. </p>
3811
3812<p>Note that if the pixel at the 'seed point' does not itself match the given
3813<var>color</var> (according to <a href="command-line-options.html#fuzz">-fuzz</a>), then no
3814action will be taken. </p>
3815
3816<p>This operator works more like the <a href="command-line-options.html#opaque">-opaque</a> option, than
3817a more general flood fill that reads the matching color directly at the 'seed
3818point'. For this form of flood fill, look at <a href="command-line-options.html#draw">-draw</a> and
3819its 'color floodfill' drawing method. </p>
3820
3821
3822<div style="margin: auto;">
3823 <h3 class="magick-header"><a id="flop"></a>-flop</h3>
3824</div>
3825
3826<p class="magick-description">create a <var>mirror image</var>.</p>
3827
3828<p>Reflect the scanlines in the horizontal direction, just like the image in
3829a vertical mirror. </p>
3830
3831
3832<div style="margin: auto;">
3833 <h3 class="magick-header"><a id="font"></a>-font <var>name</var></h3>
3834</div>
3835
3836<p class="magick-description">set the font to use when annotating images with text, or creating labels.</p>
3837
3838<p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
3839option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
3840
3841<p>In addition to the fonts specified by the above pre-defined list, you can
3842also specify a font from a specific source. For example <code>Arial.ttf</code>
3843is a TrueType font file, <code>ps:helvetica</code> is PostScript font, and
3844<code>x:fixed</code> is X11 font.</p>
3845
3846<p>For other settings that affect fonts, see the options <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3847
3848
3849<div style="margin: auto;">
3850 <h3 class="magick-header"><a id="foreground"></a>-foreground <var>color</var></h3>
3851</div>
3852
3853<p class="magick-description">Define the foreground color for menus.", "display</p>
3854
3855<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
3856
3857<p>The default foreground color is black.</p>
3858
3859<div style="margin: auto;">
3860 <h3 class="magick-header"><a id="format"></a>-format <var>type</var></h3>
3861</div>
3862
3863<p class="magick-description">the image format type.</p>
3864
3865<p>When used with the <code>mogrify</code> utility, this option converts any
3866image to the image <a href="formats.html">format</a> you specify.
3867For a list of image format types supported by ImageMagick, use <a href="command-line-options.html#list">-list format</a>.</p>
3868
3869<p>By default the file is written to its original name. However, if the
3870filename extension matches a supported format, the extension is replaced with
3871the image format type specified with <a href="command-line-options.html#format">-format</a>. For
3872example, if you specify <var>tiff</var> as the format type and the
3873input image filename is <var>image.gif</var>, the output image
3874filename becomes <var>image.tiff</var>.</p>
3875
3876<div style="margin: auto;">
3877 <h3 class="magick-header"><a id="format_identify_"></a>-format <var>string</var></h3>
3878</div>
3879
3880<p class="magick-description">output formatted image characteristics.</p>
3881
3882<p>See <a href="escape.html">Format and Print Image
3883Properties</a> for an explanation on how to specify the argument to this
3884option.</p>
3885
3886<div style="margin: auto;">
3887 <h3 class="magick-header"><a id="frame"></a>-frame <var>geometry</var></h3>
3888</div>
3889
3890<p class="magick-description">Surround the image with a border or beveled frame.</p>
3891
3892<p>The color of the border is specified with the <a href="command-line-options.html#mattecolor">-mattecolor</a> command line option. </p>
3893
3894<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <var>size</var> portion of the <var>geometry</var> argument indicates the amount of extra width and
3895height that is added to the dimensions of the image. If no offsets are given
3896in the <var>geometry</var> argument, then the border added is
3897a solid color. Offsets <var>x</var> and <var>y</var>, if present, specify that
3898the width and height of the border is partitioned to form an outer bevel of
3899thickness <var>x</var> pixels and an inner bevel of thickness
3900<var>y</var> pixels. Negative offsets make no sense as frame arguments.
3901</p>
3902
3903<p>The <a href="command-line-options.html#frame">-frame</a> option is affected by the current <a href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
3904'<code>Over</code>' composition method. It generates an image of the appropriate
3905size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
3906draws the frame of four distinct colors close to the current <a href="command-line-options.html#mattecolor">-mattecolor</a>. The original image is then overlaid onto
3907center of this image. This means that with the default compose method of
3908'<code>Over</code>' any transparent parts may be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
3909
3910<p>The image composition is not
3911affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
3912
3913
3914<div style="margin: auto;">
3915 <h3 class="magick-header"><a id="frame_import_"></a>-frame</h3>
3916</div>
3917
3918<p class="magick-description">include the X window frame in the imported image. </p>
3919<div style="margin: auto;">
3920 <h3 class="magick-header"><a id="function"></a>-function <var>function</var> <var>parameters</var></h3>
3921</div>
3922
3923<p class="magick-description">Apply a function to channel values.</p>
3924
3925<p>This operator performs calculations based on the given arguments to modify
3926each of the color values for each previously set <a href="command-line-options.html#channel">-channel</a> in the image. See <a href="command-line-options.html#evaluate">-evaluate</a> for details concerning how the results of the
3927calculations are handled.</p>
3928
3929<p>This is can be considered a multi-argument version of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
3930ImageMagick 6.4.8−8.)</p>
3931
3932<p>Here, <var>parameters</var> is a comma-separated list of
3933numerical values. The number of values varies depending on which <var>function</var> is selected. Choose the <var>function</var> from:</p>
3934
3935<pre>
3936Polynomial
3937Sinusoid
3938Arcsin
3939Arctan
3940</pre>
3941
3942<p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
3943use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
3944
3945<dl class="dl-horizontal">
3946 <dt>Polynomial</dt>
3947 <dd><p>The <code>Polynomial</code> function takes an arbitrary number of parameters,
3948these being the coefficients of a polynomial, in decreasing order of degree.
3949That is, entering</p>
3950
3951<pre>
3952-function Polynomial <var>a</var><sub><var>n</var></sub>,<var>a</var><sub><var>n</var>-1</sub>,...<var>a</var><sub>1</sub>,<var>a</var><sub>0</sub>
3953</pre>
3954
3955<p>will invoke a polynomial function given by</p>
3956
3957<pre>
3958<var>a</var><sub><var>n</var></sub> <b><var>u</var></b><sup><var>n</var></sup> + <var>a</var><sub><var>n</var>-1</sub> <b><var>u</var></b><sup><var>n</var>-1</sup> + ··· <var>a</var><sub>1</sub> <b><var>u</var></b> + <var>a</var><sub>0</sub>,
3959</pre>
3960
3961<p>where <b><var>u</var></b> is pixel's original normalized channel value.</p>
3962
3963<p>The <code>Polynomial</code> function can be used in place of <code>Set</code>
3964(the <var>constant</var> polynomial) and <code>Add</code>, <code>Divide</code>,
3965<code>Multiply</code>, and <code>Subtract</code> (some <var>linear</var>
3966polynomials) of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. The <a href="command-line-options.html#level">-level</a> operator also affects channels linearly. Some
3967correspondences follow.</p>
3968
3969<table class="table table-condensed table-striped">
3970 <tr>
3971 <td>-evaluate Set <var>value</var> </td>
3972 <td>-function Polynomial <var>value</var></td>
3973 <td>(Constant functions; set <var>value</var>×100% gray when channels are RGB.)</td>
3974 </tr>
3975 <tr>
3976 <td>-evaluate Add <var>value</var> </td>
3977 <td>-function Polynomial 1,<var>value</var></td>
3978 </tr>
3979 <tr>
3980 <td>-evaluate Subtract <var>value</var> </td>
3981 <td>-function Polynomial 1,−<var>value</var></td>
3982 </tr>
3983 <tr>
3984 <td>-evaluate Multiply <var>value</var> </td>
3985 <td>-function Polynomial <var>value</var>,0</td>
3986 </tr>
3987 <tr>
3988 <td>+level black% x white%</td>
3989 <td>-function Polynomial A,B</td>
3990 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
3991 </tr>
3992</table>
3993
3994<p>The <code>Polynomial</code> function gives great versatility, since
3995polynomials can be used to fit any continuous curve to any degree of accuracy
3996desired.</p>
3997
3998</dd>
3999<dt>Sinusoid</dt>
4000<dd>
4001<p>The <code>Sinusoid</code> function can be used to vary the channel values
4002sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
4003values are given as one to four parameters, as follows,</p>
4004
4005<pre>
4006-function <code>Sinusoid</code> <var>freq</var>,[<var>phase</var>,[<var>amp</var>,[<var>bias</var>]]]
4007</pre>
4008
4009<p>where <var>phase</var> is in degrees. (The domain [0,1] of the function
4010corresponds to 0 through <var>freq</var>×360 degrees.)
4011The result is that if a pixel's normalized channel value is originally
4012<b><var>u</var></b>, its resulting normalized value is given by </p>
4013
4014<pre>
4015<var>amp</var> * sin(2*π* (<var>freq</var> * <b><var>u</var></b> + <var>phase</var> / 360)) + <var>bias</var>
4016</pre>
4017
4018<p> For example, the following generates a curve that starts and ends at 0.9
4019(when <b><var>u</var></b>=0 and 1, resp.), oscillating three times between
4020.7−.2=.5 and .7+.2=.9. </p>
4021
4022<pre>
4023-function Sinusoid 3,-90,.2,.7
4024</pre>
4025
4026<p>The default values of <var>amp</var> and <var>bias</var> are both .5. The default for <var>phase</var>
4027is 0.</p>
4028
4029<p>The <code>Sinusoid</code> function generalizes <code>Sin</code> and
4030<code>Cos</code> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
4031varying amplitude, phase and bias. The correspondence is as follows.</p>
4032
4033<table class="table table-condensed table-striped">
4034 <tr>
4035 <td>-evaluate Sin <var>freq</var> </td>
4036 <td>-function Sinusoid <var>freq</var>,0 </td>
4037 </tr>
4038 <tr>
4039 <td>-evaluate Cos <var>freq</var> </td>
4040 <td>-function Sinusoid <var>freq</var>,90 </td>
4041 </tr>
4042</table>
4043 </dd>
4044<dt>ArcSin</dt>
4045<dd>
4046<p>The <code>ArcSin</code> function generates the inverse curve of a Sinusoid,
4047and can be used to generate cylindrical distortion and displacement maps.
4048The curve can be adjusted relative to both the input values and output range
4049of values.</p>
4050
4051<pre>
4052-function <code>ArcSin</code> <var>width</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4053</pre>
4054
4055<p>with all values given in terms of normalized color values (0.0 for black,
40561.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
4057for bout input (<var>width</var>), and output (<var>width</var>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
4058
4059<pre>
4060<var>range</var>/π * asin( 2/<var>width</var> * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4061</pre>
4062
4063</dd>
4064<dt>ArcTan</dt>
4065<dd>
4066<p>The <code>ArcTan</code> function generates a curve that smooth crosses from
4067limit values at infinities, though a center using the given slope value.
4068All these values can be adjusted via the arguments.</p>
4069
4070<pre>
4071-function <code>ArcTan</code> <var>slope</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4072</pre>
4073
4074<p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
4075</p>
4076
4077<pre>
4078<var>range</var>/π * atan( <var>slope</var>*π * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4079</pre>
4080 </dd>
4081
4082</dl>
4083
4084
4085
4086<div style="margin: auto;">
4087 <h3 class="magick-header"><a id="fuzz"></a>-fuzz <var>distance</var>{<var>%</var>}</h3>
4088</div>
4089
4090<p class="magick-description">Colors within this <var>distance</var> are considered equal.</p>
4091
4092<p>A number of algorithms search for a target color. By default the color must
4093be exact. Use this option to match colors that are close to the target color
4094in RGB space. For example, if you want to automagically trim the edges of an
4095image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
4096background color may differ by a small amount. This option can account for
4097these differences.</p>
4098
4099<p>The <var>distance</var> can be in absolute intensity units or, by
4100appending <code>%</code> as a percentage of the maximum possible intensity (255,
410165535, or 4294967295).</p>
4102
4103<p>Use <a href="command-line-options.html#fuzz">+fuzz</a> to reset the fuzz value to 0.</p>
4104
4105
4106<div style="margin: auto;">
4107 <h3 class="magick-header"><a id="fx"></a>-fx <var>expression</var></h3>
4108</div>
4109
4110<p class="magick-description">apply a mathematical expression to an image or image channels.</p>
4111
4112<p>If the first character of <var>expression</var> is <code>@</code>,
4113the expression is read from a file titled by the remaining characters in the
4114string.</p>
4115
4116<p>See <a href="fx.html">FX,
4117The Special Effects Image Operator</a> for a detailed discussion of this
4118option.</p>
4119
4120
4121<div style="margin: auto;">
4122 <h3 class="magick-header"><a id="gamma"></a>-gamma <var>value</var></h3>
4123</div>
4124
4125<p class="magick-description">level of gamma correction.</p>
4126
4127<p>The same color image displayed on two different workstations may look
4128different due to differences in the display monitor. Use gamma correction to
4129adjust for this color difference. Reasonable values extend from
4130<code>0.8</code> to <code>2.3</code>. Gamma less than 1.0 darkens the image and
4131gamma greater than 1.0 lightens it. Large adjustments to image gamma may
4132result in the loss of some image information if the pixel quantum size is only
4133eight bits (quantum range 0 to 255).</p>
4134
4135<p>Gamma adjusts the image's channel values pixel-by-pixel according to
4136a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
4137normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
4138same as taking the square root of the image.</p>
4139
4140<p>You can apply separate gamma values to the red, green, and blue channels of
4141the image with a gamma value list delimited with commas (e.g.,
4142<code>1.7,2.3,1.2</code>).</p>
4143
4144<p>Use <a href="command-line-options.html#gamma">+gamma <var>value</var></a> to set the
4145image gamma level without actually adjusting the image pixels. This option
4146is useful if the image is of a known gamma but not set as an image attribute
4147(e.g. PNG images). Write the "file gamma" which is the reciprocal of the
4148display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
4149chunk, use</p>
4150
4151<pre>
4152convert input.png +gamma .45455 output.png
4153</pre>
4154
4155<p>(0.45455 is 1/2.2)</p>
4156
4157<p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
4158
4159<div style="margin: auto;">
4160 <h3 class="magick-header"><a id="gaussian-blur"></a>-gaussian-blur <var>radius</var><br>-gaussian-blur <var>radius</var>x<var>sigma</var></h3>
4161</div>
4162
4163<p class="magick-description">Blur the image with a Gaussian operator.</p>
4164
4165<p>Convolve the image with a Gaussian or normal distribution using the given
4166<var>Sigma</var> value. The formula is:</p>
4167
4168<p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"> </p>
4169
4170<p>The <var>Sigma</var> value is the important argument, and
4171determines the actual amount of blurring that will take place. </p>
4172
4173<p>The <var>Radius</var> is only used to determine the size of the
4174array which will hold the calculated Gaussian distribution. It should be an
4175integer. If not given, or set to zero, IM will calculate the largest possible
4176radius that will provide meaningful results for the Gaussian distribution.
4177</p>
4178
4179<p>The larger the <var>Radius</var> the radius the slower the
4180operation is. However too small a <var>Radius</var>, and sever
4181aliasing effects may result. As a guideline, <var>Radius</var>
4182should be at least twice the <var>Sigma</var> value, though three
4183times will produce a more accurate result. </p>
4184
4185<p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4186full 2-dimensional convolution is used to generate the weighted average of the
4187neighboring pixels. </p>
4188
4189<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4190pixels which are outside the image proper are blurred into the final result.
4191</p>
4192
4193
4194<div style="margin: auto;">
4195 <h3 class="magick-header"><a id="geometry"></a>-geometry <var>geometry</var></h3>
4196</div>
4197
4198<p class="magick-description">Set the preferred size and location of the image.</p>
4199
4200<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4201
4202<div style="margin: auto;">
4203 <h3 class="magick-header"><a id="gravity"></a>-gravity <var>type</var></h3>
4204</div>
4205
4206<p class="magick-description">Sets the current gravity suggestion for various other settings and options.</p>
4207
4208<p>Choices include: <code>NorthWest</code>, <code>North</code>,
4209<code>NorthEast</code>, <code>West</code>, <code>Center</code>, <code>East</code>,
4210<code>SouthWest</code>, <code>South</code>, <code>SouthEast</code>. Use <a href="command-line-options.html#list">-list gravity</a> to get a complete list of <a href="command-line-options.html#gravity">-gravity</a> settings available in your ImageMagick
4211installation.</p>
4212
4213<p>The direction you choose specifies where to position text or subimages. For
4214example, a gravity of <code>Center</code> forces the text to be centered within
4215the image. By default, the image gravity is <code>NorthWest</code>. See <a href="command-line-options.html#draw">-draw</a> for more details about graphic primitives. Only the
4216text primitive of <a href="command-line-options.html#draw">-draw</a> is affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
4217
4218<p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4219<a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4220take <var>geometry</var> as an argument, such as the <a href="command-line-options.html#crop">-crop</a> option. </p>
4221
4222<p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4223or setting having a <var>geometry</var> argument that specifies an
4224offset, the offset is usually applied to the point within the image suggested
4225by the <a href="command-line-options.html#gravity">-gravity</a> argument. Thus, in the following
4226command, for example, suppose the file <code>image.png</code> has dimensions
4227200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4228is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4229<code>Center</code>, which suggests the midpoint of the image, at the point
4230(100,50). The offset (−40,20) is applied to that point, giving
4231(100−40,50+20)=(60,70), so the specified 10x10 region is located at
4232that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4233region itself, which is <var>centered</var> at the pixel
4234coordinate (60,70). (See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.)</p>
4235
4236<pre>
4237convert image.png -gravity Center -region 10x10-40+20 \
4238 -negate output.png
4239</pre>
4240
4241<p>When used as an option to <a href="composite.html">composite</a>, <a href="command-line-options.html#gravity">-gravity</a> gives the direction that the image gravitates
4242within the composite.</p>
4243
4244<p>When used as an option to <a href="montage.html">montage</a>, <a href="command-line-options.html#gravity">-gravity</a> gives the direction that an image gravitates
4245within a tile. The default gravity is <code>Center</code> for this purpose.</p>
4246
4247
4248<div style="margin: auto;">
4249 <h3 class="magick-header"><a id="grayscale"></a>-grayscale <var>method</var></h3>
4250</div>
4251
4252<p class="magick-description">convert image to grayscale.</p>
4253
4254<p>This will use one of the <a href="command-line-options.html#intensity">-intensity</a> methods to
4255convert the given image into a linear-grayscale image. </p>
4256
4257<p>For example, to convert an image to (linear) Rec709Luminance grayscale, type:</p>
4258
4259<pre>
4260convert in.png -grayscale Rec709Luminance out.png
4261</pre>
4262
4263<p>which is equivalent to:</p>
4264
4265<pre>
4266convert in.png -colorspace gray out.png
4267</pre>
4268
4269<p>Similarly, to convert an image to (non-linear) Rec709Luma grayscale, type:</p>
4270
4271<pre>
4272convert in.png -grayscale Rec709Luma out.png
4273</pre>
4274
4275<p>which is equivalent to:</p>
4276
4277<pre>
4278convert in.png -set colorspace RGB -colorspace gray out.png
4279</pre>
4280
4281<p>Note that a 'colorspace' intensity method will produce the same result
4282regardless of the current colorpsace of the image. But a 'mathematical'
4283intensity method will depend on the current colorspace the image is currently
4284using. </p>
4285
4286<p>While this operation uses an <a href="command-line-options.html#intensity">-intensity</a> method,
4287it does not use or set the <a href="command-line-options.html#intensity">-intensity</a> setting, so
4288will not effect other operations that may use that setting.</p>
4289
4290
4291<div style="margin: auto;">
4292 <h3 class="magick-header"><a id="green-primary"></a>-green-primary <var>x,y</var></h3>
4293</div>
4294
4295<p class="magick-description">green chromaticity primary point.</p>
4296
4297
4298<div style="margin: auto;">
4299 <h3 class="magick-header"><a id="hald-clut"></a>-hald-clut</h3>
4300</div>
4301
4302<p class="magick-description">apply a Hald color lookup table to the image.</p>
4303
4304<p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4305dimensions. Create it with the <code>HALD:</code> prefix (e.g. HALD:8). You
4306can apply any color transformation to the Hald image and then use this option
4307to apply the transform to the image. </p>
4308
4309<pre>
4310convert image.png hald.png -hald-clut transform.png
4311</pre>
4312
4313<p>This option provides a convenient method for you to use Gimp or Photoshop
4314to make color corrections to the Hald CLUT image and subsequently apply them
4315to multiple images using an ImageMagick script. </p>
4316
4317<p>Note that the representation is only of the normal RGB color space and that
4318the whole color value triplet is used for the interpolated lookup of the
4319represented Hald color cube image. Because of this the operation is not <a href="command-line-options.html#channel">-channel</a> setting effected, nor can it adjust or modify an
4320images transparency or alpha/matte channel.</p>
4321
4322<p>See also <a href="command-line-options.html#clut">-clut</a> which provides color value replacement
4323of the individual color channels, usually involving a simpler gray-scale
4324image. E.g: gray-scale to color replacement, or modification by a histogram
4325mapping. </p>
4326
4327
4328<div style="margin: auto;">
4329 <h3 class="magick-header"><a id="help"></a>-help</h3>
4330</div>
4331
4332<p class="magick-description">print usage instructions.</p>
4333
4334<div style="margin: auto;">
4335 <h3 class="magick-header"><a id="highlight-color"></a>-highlight-color <var>color</var></h3>
4336</div>
4337
4338<p class="magick-description">when comparing images, emphasize pixel differences with this color.</p>
4339
4340<div style="margin: auto;">
4341 <h3 class="magick-header"><a id="hough-lines"></a>-hough-lines <var>width</var>x<var>height</var>{<var>+threshold</var>}</h3>
4342</div>
4343
4344<p class="magick-description">identify straight lines in the image (e.g. -hough-lines 9x9+195).</p>
4345
4346<p>Use the Hough line detector with any binary edge extracted image to locate and draw any straight lines that it finds.</p>
4347
4348<p>The process accumulates counts for every white pixel in the binary edge image for every possible orientation (for angles from 0 to 179 in 1 deg increments) and distance from the center of the image to the corners (in 1 px increments). It stores the counts in an accumulator matrix of angle vs distance. The size of the accumulator will be 180x(diagonal/2). Next it searches the accumulator for peaks in counts and converts the locations of the peaks to slope and intercept in the normal x,y input image space. The algorithm uses slope/intercepts to find the endpoints clipped to the bounds of the image. The lines are drawn from the given endpoints. The counts are a measure of the length of the lines.</p>.
4349
4350<p>The WxH arguments specify the filter size for locating the peaks in the Hough accumulator. The threshold excludes lines whose counts are less than the threshold value.</p>
4351
4352<p>Use <code><a href="command-line-options.html#background">-background</a></code> to specify the color of the background onto which the lines will be drawn. The default is black.</p>
4353
4354<p>Use <code><a href="command-line-options.html#fill">-fill</a></code> to specify the color of the lines. The default is black.</p>
4355
4356<p>Use <code><a href="command-line-options.html#stroke">-stroke</a></code> and <code><a href="command-line-options.html#strokewidth">-strokewidth</a></code> to specify the thickness of the lines. The default is black and no strokewidth.</p>
4357
4358<p>A text file listing the endpoints and counts may be created by using the suffix, .mvg, for the output image.</p>
4359
4360<p>Use <code><a href="command-line-options.html#define">-define</a> hough-lines:accumulator=true</code> to return the accumulator image in addition to the lines image.</p>
4361
4362<div style="margin: auto;">
4363 <h3 class="magick-header"><a id="iconGeometry"></a>-iconGeometry <var>geometry</var></h3>
4364</div>
4365
4366<p class="magick-description">specify the icon geometry.</p>
4367
4368<p>Offsets, if present in the geometry specification, are handled in the same
4369manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4370handle negative offsets.</p>
4371
4372<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4373
4374<div style="margin: auto;">
4375 <h3 class="magick-header"><a id="iconic"></a>-iconic</h3>
4376</div>
4377
4378<p class="magick-description">start in icon mode in X Windows", 'animate', 'display</p>
4379
4380<div style="margin: auto;">
4381 <h3 class="magick-header"><a id="identify"></a>-identify</h3>
4382</div>
4383
4384<p class="magick-description">identify the format and characteristics of the image.</p>
4385
4386<p>This information is printed: image scene number; image name; image size;
4387the image class (<var>DirectClass</var> or <var>PseudoClass</var>); the total number of unique colors; and the
4388number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4389a description of the image class.</p>
4390
4391<p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4392in the image and color reduction error values are printed. Refer to <a href="quantize.html">color
4393reduction algorithm</a> for a description of these values.</p>
4394
4395<p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4396amounts of image properties are displayed including image statistics, profiles,
4397image histogram, and others.</p>
4398
4399<div style="margin: auto;">
4400 <h3 class="magick-header"><a id="ift"></a>-ift</h3>
4401</div>
4402
4403<p class="magick-description">implements the inverse discrete Fourier transform (DFT).</p>
4404
4405<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4406users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4407images from the frequency domain to a single image in the normal or spatial
4408domain. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4409<a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4410<a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4411
4412<p>For example, depending upon the image format used to store the result of
4413the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4414
4415<pre>
4416convert fft_image.miff -ift fft_image_ift.png
4417</pre>
4418
4419<p>or</p>
4420
4421<pre>
4422convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png
4423</pre>
4424
4425<p>The resulting image may need to be cropped due to padding introduced when
4426the original image, prior to the <a href="command-line-options.html#fft">-fft</a> or <a href="command-line-options.html#fft">+fft</a>, was not square or even dimensioned. Any padding is at
4427the right and/or bottom sides of the image.</p>
4428
4429<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4430use <a href="command-line-options.html#ift">-ift</a>.</p>
4431
4432<p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4433and imaginary images from the frequency domain to a single image in the normal
4434(spatial) domain.</p>
4435
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]4436<p>By default the IFT is not normalized (and the FFT is). Use "<code><a href="command-line-options.html#define">-define</a> fourier:normalize=inverse</code> to explicitly normalize the IFT and unnormalize the FFT.</p>
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]4437
4438<div style="margin: auto;">
4439 <h3 class="magick-header"><a id="immutable"></a>-immutable</h3>
4440</div>
4441
4442<p class="magick-description">make image immutable.</p>
4443
4444<div style="margin: auto;">
4445 <h3 class="magick-header"><a id="implode"></a>-implode <var>factor</var></h3>
4446</div>
4447
4448<p class="magick-description">implode image pixels about the center.</p>
4449
4450<div style="margin: auto;">
4451 <h3 class="magick-header"><a id="insert"></a>-insert <var>index</var></h3>
4452</div>
4453
4454<p class="magick-description">insert the last image into the image sequence.</p>
4455
4456<p>This option takes last image in the current image sequence and inserts it
4457at the given index. If a negative index is used, the insert position is
4458calculated before the last image is removed from the sequence. As such
4459<code>-insert -1</code> will result in no change to the image sequence.</p>
4460
4461<p>The <code>+insert</code> option is equivalent to <code>-insert -1</code>. In
4462other words, insert the last image, at the end of the current image sequence.
4463Consequently this has no effect on the image sequence order.</p>
4464
4465<div style="margin: auto;">
4466 <h3 class="magick-header"><a id="intensity"></a>-intensity <var>method</var></h3>
4467</div>
4468
4469<p class="magick-description">method to generate intensity value from pixel.</p>
4470
4471<p>ImageMagick provides a number of methods used in situations where an
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]4472operator needs to determine a single grayscale value for some purpose, from
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]4473an image with red, green, and blue pixel components. Typically the linear
4474<code>Rec709Luminance</code> formula is used, which is the same formula used when
4475converting images to <code>-colorspace gray</code>. </p>
4476
4477<p>The following formulas are currently provided, and will first convert
4478the pixel values to linear-RGB or non-linear sRGB colorspace before
4479being applied to calulate the final greyscale value. </p>
4480
4481<dl class="dl-horizontal">
4482<dt>Rec601Luma</dt><dd> 0.298839R' + 0.586811G'+ 0.114350B'</dd>
4483<dt>Rec601Luminance</dt><dd> 0.298839R + 0.586811G + 0.114350B</dd>
4484<dt>Rec709Luma</dt><dd> 0.212656R' + 0.715158G' + 0.072186B'</dd>
4485<dt>Rec709Luminance</dt><dd> 0.212656R + 0.715158G + 0.072186B</dd>
4486<dt>Brightness</dt><dd> max(R', G', B')</dd>
4487<dt>Lightness</dt><dd> (min(R', G', B') + max(R', G', B')) / 2.0</dd>
4488</dl>
4489
4490<p>Note that the above R,G,B values is the image's linear-RGB values, while
4491R',G',B' are sRGB non-linear values. </p>
4492
4493<p>These intensity methods are mathematical in nature and will use the
4494current value in the images respective R,G,B channel regardless of
4495what that is, or what colorspace the image is currently using.</p>
4496
4497<dl class="dl-horizontal">
4498<dt>Average</dt><dd>(R + G + B) / 3.0</dd>
4499<dt>MS</dt><dd>(R^2 + G^2 + B^2) / 3.0</dd>
4500<dt>RMS</dt><dd>sqrt( (R^2 + G^2 + B^2) / 3.0 )</dd>
4501</dl>
4502
4503<p>These methods are often used for other purposes, such as generating a
4504grayscale difference image between two color images (using <a href="command-line-options.html#compose">-compose</a> '<code>Difference</code>' composition. </p>
4505
4506<p> For example The 'MS' (Mean Squared) setting is good for minimizing color
4507error comparisions. While... The method 'RMS' (Root Mean Squared) for
4508example is appropriate for calculating color vector distance, from a color
4509difference image. This is equivalent to the color only component of the <a href="command-line-options.html#fuzz">-fuzz</a> factor color compare setting. </p>
4510
4511<p>See also <a href="command-line-options.html#grayscale">-grayscale</a> which applies one of the above
4512grayscaling formula directly to an image without setting the <a href="command-line-options.html#intensity">-intensity</a> setting.</p>
4513
4514<p>The <a href="command-line-options.html#colorspace">-colorspace gray</a> image conversion also uses
4515the current intensity setting, but will always convert the image to the
4516appropriate sRGB or linear-RGB colorspace before appling the above
4517function.</p>
4518
4519<p>To print a complete list of posible pixel intensity setting methods, use <a href="command-line-options.html#list">-list intensity</a>.</p>
4520
4521<p>Operators affected by the <a href="command-line-options.html#intensity">-intensity</a> setting include:</p>
4522
4523<pre>
4524-adaptive-blur
4525-adaptive-sharpen
4526-black-threshold
4527-clut (when mapping greyscale CLUT image to alpha channel if set by -channels)
4528-colors for gray colorspace
4529-compose {LightenIntensity, DarkenIntensity, CopyOpacity, CopyBlack}
4530-contrast-stretch
4531-distort {ErodeIntensity, DilateIntensity}
4532-normalize
4533-random-threshold
4534-selective-blur
4535-shade
4536-threshold
4537-tint
4538-white-threshold
4539</pre>
4540
4541<div style="margin: auto;">
4542 <h3 class="magick-header"><a id="intent"></a>-intent <var>type</var></h3>
4543</div>
4544
4545<p class="magick-description">use this type of rendering intent when managing the image color.</p>
4546
4547<p>Use this option to affect the color management operation of an image (see
4548<a href="command-line-options.html#profile">-profile</a>). Choose from these intents: <code>Absolute,
4549Perceptual, Relative, Saturation</code>.</p>
4550
4551<p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4552
4553<p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4554
4555<div style="margin: auto;">
4556 <h3 class="magick-header"><a id="interlace"></a>-interlace <var>type</var></h3>
4557</div>
4558
4559<p class="magick-description">the type of interlacing scheme.</p>
4560
4561<p>Choose from:</p>
4562
4563<pre>
4564none
4565line
4566plane
4567partition
4568JPEG
4569GIF
4570PNG
4571</pre>
4572
4573<p>This option is used to specify the type of interlacing scheme for raw image
4574formats such as <code>RGB</code> or <code>YUV</code>.</p>
4575
4576<p><code>None</code> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4577
4578<p><code>Line</code> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4579
4580<p><code>Plane</code> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4581
4582<p><code>Partition</code> is like plane except the different planes are saved to
4583individual files (e.g. image.R, image.G, and image.B).</p>
4584
4585<p>Use <code>Line</code> or <code>Plane</code> to create an <code>interlaced
4586PNG</code> or <code>GIF</code> or <code>progressive JPEG</code> image.</p>
4587
4588<p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4589interlace</a>.</p>
4590
4591<div style="margin: auto;">
4592 <h3 class="magick-header"><a id="interpolate"></a>-interpolate <var>type</var></h3>
4593</div>
4594
4595<p class="magick-description">Set the pixel color interpolation method to use when looking up a color based on a floating point or real value.</p>
4596
4597<p>When looking up the color of a pixel using a non-integer floating point
4598value, you typically fall in between the pixel colors defined by the source
4599image. This setting determines how the color is determined from the colors of
4600the pixels surrounding that point. That is how to determine the color of a
4601point that falls between two, or even four different colored pixels. </p>
4602
4603<dl class="dl-horizontal">
4604 <dt>integer</dt>
4605 <dd>The color of the top-left pixel (floor function)</dd>
4606 <dt>nearest-neighbor</dt>
4607 <dd>The nearest pixel to the lookup point (rounded function)</dd>
4608 <dt>average</dt>
4609 <dd>The average color of the surrounding four pixels</dd>
4610 <dt>bilinear</dt>
4611 <dd>A double linear interpolation of pixels (the default)</dd>
4612 <dt>mesh</dt>
4613 <dd>Divide area into two flat triangular interpolations</dd>
4614 <dt>bicubic</dt>
4615 <dd>Fitted bicubic-spines of surrounding 16 pixels</dd>
4616 <dt>spline</dt>
4617 <dd>Direct spline curves (colors are blurred)</dd>
4618 <dt>filter</dt>
4619 <dd>Use resize <a href="command-line-options.html#filter">-filter</a> settings</dd>
4620</dl>
4621
4622<p>This most important for distortion operators such as <a href="command-line-options.html#distort">-distort</a>, <a href="command-line-options.html#implode">-implode</a>, <a href="command-line-options.html#transform">-transform</a> and <a href="command-line-options.html#fx">-fx</a>. </p>
4623
4624<p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4625
4626<p>See also <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a>, for control of the
4627lookup for positions outside the boundaries of the image. </p>
4628
4629
4630<div style="margin: auto;">
4631 <h3 class="magick-header"><a id="interline-spacing"></a>-interline-spacing <var>value</var></h3>
4632</div>
4633
4634<p class="magick-description">the space between two text lines.</p>
4635
4636<div style="margin: auto;">
4637 <h3 class="magick-header"><a id="interword-spacing"></a>-interword-spacing <var>value</var></h3>
4638</div>
4639
4640<p class="magick-description">the space between two words.</p>
4641
4642<div style="margin: auto;">
4643 <h3 class="magick-header"><a id="kerning"></a>-kerning <var>value</var></h3>
4644</div>
4645
4646<p class="magick-description">the space between two letters.</p>
4647
4648<div style="margin: auto;">
4649 <h3 class="magick-header"><a id="kuwahara"></a>-kuwahara <var>radius</var><br>-kuwahara <var>radius</var>x<var>sigma</var></h3>
4650</div>
4651
4652<p class="magick-description">edge preserving noise reduction filter.</p>
4653
4654<p>The <var>radius</var> is more important than the <var>sigma</var>. If <var>sigma</var> is left off, it will be computed automatically from the <var>radius</var> as <var>sigma</var>=<var>radius</var>-0.5. The <var>sigma</var> provides a bit of additional smoothing control.</p>
4655
4656
4657<div style="margin: auto;">
4658 <h3 class="magick-header"><a id="label"></a>-label <var>name</var></h3>
4659</div>
4660
4661<p class="magick-description">assign a label to an image.</p>
4662
4663<p>Use this option to assign a specific label to the image, as it is read in
4664or created. You can use the <a href="command-line-options.html#set">-set</a> operation to re-assign
4665a the labels of images already read in. Image formats such as TIFF, PNG,
4666MIFF, supports saving the label information with the image.</p>
4667
4668<p>When saving an image to a <var>PostScript</var> file, any label
4669assigned to an image is used as a header string to print above the postscript
4670image. </p>
4671
4672<p>You can include the image filename, type, width, height, or other image
4673attribute by embedding special format character. See <a href="escape.html">Format and Print Image
4674Properties</a> for details of the percent escape codes.</p>
4675
4676<p>For example,</p>
4677
4678<pre>
4679-label "%m:%f %wx%h" bird.miff
4680</pre>
4681
4682<p>assigns an image label of <code>MIFF:bird.miff 512x480</code> to the
4683"<code>bird.miff</code>" image and whose width is 512 and height is 480, as it
4684is read in. If a <a href="command-line-options.html#label">+label</a> option was used instead, any
4685existing label present in the image would be used. You can remove all labels
4686from an image by assigning the empty string. </p>
4687
4688<p>A label is not drawn on the image, but is embedded in the image datastream
4689via <var>Label</var> tag or similar mechanism. If you want the label to be
4690visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
4691during the final processing in the creation of an image montage.</p>
4692
4693<p>If the first character of <var>string</var> is <var>@</var>, the image label is read from a file titled by the
4694remaining characters in the string. Labels in a file are literal, no embedded
4695formatting characters are recognized.</p>
4696
4697
4698<div style="margin: auto;">
4699 <h3 class="magick-header"><a id="lat"></a>-lat <var>width</var><br>-lat <var>width</var>x<var>height</var>{<var>+-</var>}<var>offset</var>{<var>%</var>}</h3>
4700</div>
4701
4702<p class="magick-description">perform local adaptive threshold.</p>
4703
4704<p>Adaptively threshold each pixel based on the value of pixels in a
4705surrounding window. If the current pixel is lighter than this average plus
4706the optional <code>offset</code>, then it is made white, otherwise it is made
4707black. Small variations in pixel values such as found in scanned documents
4708can be ignored if offset is positive. A negative offset will make it more
4709sensitive to those small variations. </p>
4710
4711<p>This is commonly used to threshold images with an uneven background. It is
4712based on the assumption that average color of the small window is the
4713the local background color, from which to separate the foreground color. </p>
4714
4715
4716<div style="margin: auto;">
4717 <h3 class="magick-header"><a id="layers"></a>-layers <var>method</var></h3>
4718</div>
4719
4720<p class="magick-description">handle multiple images forming a set of image layers or animation frames.</p>
4721
4722<p>Perform various image operation methods to a ordered sequence of images
4723which may represent either a set of overlaid 'image layers', a GIF disposal
4724animation, or a fully-'coalesced' animation sequence. </p>
4725
4726<table class="table table-condensed table-striped">
4727 <tbody>
4728 <tr>
4729 <th style="width: 8%">Method</th>
4730 <th>Description</th>
4731 </tr>
4732
4733 <tr>
4734 <td>compare-any</td>
4735 <td>Crop the second and later frames to the smallest rectangle
4736 that contains all the differences between the two images. No GIF <a href="command-line-options.html#dispose">-dispose</a> methods are taken into account. </td>
4737 </tr>
4738
4739 <tr><td></td><td>This exactly the same as the <a href="command-line-options.html#deconstruct">-deconstruct</a> operator, and does not preserve animations normal
4740 working, especially when animation used layer disposal methods such as
4741 '<code>Previous</code>' or '<code>Background</code>'. </td>
4742 </tr>
4743
4744 <tr>
4745 <td>compare-clear</td>
4746 <td>As '<code>compare-any</code>' but crop to the bounds of any
4747 opaque pixels which become transparent in the second frame. That is the
4748 smallest image needed to mask or erase pixels for the next frame. </td>
4749 </tr>
4750
4751 <tr>
4752 <td>compare-overlay</td>
4753 <td>As '<code>compare-any</code>' but crop to pixels that add
4754 extra color to the next image, as a result of overlaying color pixels.
4755 That is the smallest single overlaid image to add or change colors. </td>
4756 </tr>
4757
4758 <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose">-compose</a> alpha
4759 composition method '<code>change-mask</code>', to reduce the image to
4760 just the pixels that need to be overlaid. </td>
4761 </tr>
4762
4763 <tr>
4764 <td>coalesce</td>
4765 <td>Equivalent to a call to the <a href="command-line-options.html#coalesce">-coalesce</a> operator. Apply the layer disposal methods set in the
4766 current image sequence to form a fully defined animation sequence, as
4767 it should be displayed. Effectively converting a GIF animation into a
4768 'film strip'-like animation. </td>
4769 </tr>
4770
4771 <tr>
4772 <td>composite</td>
4773 <td>Alpha Composition of two image lists, separated by a
4774 "<code>null:</code>" image, with the destination image list first, and
4775 the source images last. An image from each list are composited
4776 together until one list is finished. The separator image and source
4777 image lists are removed. </td>
4778 </tr>
4779
4780
4781 <tr><td></td>
4782 <td>The <a href="command-line-options.html#geometry">-geometry</a> offset is adjusted according
4783 to <a href="command-line-options.html#gravity">-gravity</a> in accordance of the virtual
4784 canvas size of the first image in each list. Unlike a normal <a href="command-line-options.html#composite">-composite</a> operation, the canvas offset is also
4785 added to the final composite positioning of each image. </td> </tr>
4786
4787 <tr><td></td>
4788 <td>If one of the image lists only contains one image, that image is
4789 applied to all the images in the other image list, regardless of which
4790 list it is. In this case it is the image meta-data of the list which
4791 preserved. </td>
4792 </tr>
4793
4794
4795 <tr>
4796 <td>dispose</td>
4797 <td>This like '<code>coalesce</code>' but shows the look of
4798 the animation after the layer disposal method has been applied, before
4799 the next sub-frame image is overlaid. That is the 'dispose' image that
4800 results from the application of the GIF <a href="command-line-options.html#dispose">-dispose</a> method. This allows you to check what
4801 is going wrong with a particular animation you may be developing.
4802 </td>
4803 </tr>
4804
4805 <tr>
4806 <td>flatten</td>
4807 <td>Create a canvas the size of the first images virtual
4808 canvas using the current <a href="command-line-options.html#background">-background</a> color,
4809 and <a href="command-line-options.html#compose">-compose</a> each image in turn onto that
4810 canvas. Images falling outside that canvas is clipped. Final
4811 image will have a zero virtual canvas offset. </td>
4812 </tr>
4813
4814 <tr><td></td>
4815 <td>This usually used as one of the final 'image layering' operations
4816 overlaying all the prepared image layers into a final image. </td>
4817 </tr>
4818
4819 <tr><td></td>
4820 <td>For a single image this method can also be used to fillout a virtual
4821 canvas with real pixels, or to underlay an opaque color to remove
4822 transparency from an image.</td>
4823 </tr>
4824
4825
4826 <tr>
4827 <td>merge</td>
4828 <td>As 'flatten' method but merging all the given image
4829 layers to create a new layer image just large enough to hold all the
4830 image without clipping or extra space. The new images virtual offset
4831 will preserve the position of the new layer, even if this offset is
4832 negative. The virtual canvas size of the first image is preserved.
4833 </td>
4834 </tr>
4835
4836 <tr><td></td><td>Caution is advised when handling image layers with
4837 negative offsets as few image file formats handle them correctly.
4838 Following this operation method with <a href="command-line-options.html#repage">+repage</a>
4839 will remove the layer offset, and create an image in which all the
4840 overlaid image positions relative to each other is preserved, though
4841 not necessarily exactly where you specified them.
4842 </td>
4843 </tr>
4844
4845 <tr><td></td><td>See also 'trim-bounds' below which is closely related but
4846 without doing the'flatten' to merge the images together. </td>
4847 </tr>
4848
4849 <tr>
4850 <td>mosaic</td>
4851 <td>As 'flatten' method but expanding the initial canvas size
4852 of the first image in a positive direction only so as to hold all the
4853 image layers. However as a virtual canvas is 'locked' to the origin,
4854 by its own definition, image layers with a negative offsets will still
4855 become clipped by the top and left edges. See 'merge' or 'trim-bounds'
4856 if this could be a problem. </td>
4857
4858 </tr>
4859
4860 <tr><td></td><td>This method is commonly used to layout individual image
4861 using various offset but without knowing the final canvas size. The
4862 resulting image will, like 'flatten' not have any virtual offset, so
4863 can be saved to any image file format. </td>
4864 </tr>
4865
4866
4867 <tr>
4868 <td>optimize</td>
4869 <td>Optimize a coalesced animation, into GIF animation using
4870 a number of general techniques. This currently a short cut to
4871 apply both the '<code>optimize-frame</code>', and
4872 '<code>optimize-transparency</code>' methods but may be expanded to
4873 include other optimization methods as they are developed. </td>
4874 </tr>
4875
4876 <tr>
4877 <td>optimize-frame</td>
4878 <td>Optimize a coalesced animation, into GIF animation by
4879 reducing the number of pixels per frame as much as possible by
4880 attempting to pick the best layer disposal method to use, while ensuring
4881 the result will continue to animate properly. </td>
4882 </tr>
4883
4884 <tr><td></td><td> There is no guarantee that the best optimization is found.
4885 But then no reasonably fast GIF optimization algorithm can do this.
4886 However this does seem to do better than most other GIF frame
4887 optimizers seen. </td>
4888 </tr>
4889
4890 <tr>
4891 <td>optimize-plus</td>
4892 <td>As '<code>optimize-frame</code>' but attempt to improve the
4893 overall optimization by adding extra frames to the animation, without
4894 changing the final look or timing of the animation. The frames are
4895 added to attempt to separate the clearing of pixels from the
4896 overlaying of new additional pixels from one animation frame to the
4897 next. If this does not improve the optimization (for the next frame
4898 only), it will fall back to the results of the previous normal
4899 '<code>optimize-frame</code>' technique. </td>
4900 </tr>
4901
4902 <tr><td></td><td>There is the possibility that the change in the disposal
4903 style will result in a worsening in the optimization of later frames,
4904 though this is unlikely. In other words there no guarantee that it is
4905 better than the normal '<code>optimize-frame</code>' technique. For some
4906 animations however you can get a vast improvement in the final
4907 animation size. </td>
4908 </tr>
4909
4910 <tr>
4911 <td>optimize-transparency</td>
4912 <td>Given a GIF animation, replace any pixel in the sub-frame
4913 overlay images with transparency, if it does not change the resulting
4914 animation by more than the current <a href="command-line-options.html#fuzz">-fuzz</a> factor.
4915 </td>
4916 </tr>
4917
4918 <tr><td></td><td>This should allow a existing frame optimized GIF animation
4919 to compress into a smaller file size due to larger areas of one
4920 (transparent) color rather than a pattern of multiple colors repeating
4921 the current disposed image of the last frame. </td>
4922 </tr>
4923
4924 <tr>
4925 <td>remove-dups</td>
4926 <td>Remove (and merge time delays) of duplicate consecutive
4927 images, so as to simplify layer overlays of coalesced animations.
4928 </td>
4929 </tr>
4930
4931 <tr><td></td><td>Usually this a result of using a constant time delay
4932 across the whole animation, or after a larger animation was split into
4933 smaller sub-animations. The duplicate frames could also have been
4934 used as part of some frame optimization methods. </td>
4935 </tr>
4936
4937 <tr>
4938 <td>remove-zero</td>
4939 <td>Remove any image with a zero time delay, unless ALL the
4940 images have a zero time delay (and is not a proper timed animation, a
4941 warning is then issued). </td>
4942 </tr>
4943
4944 <tr><td></td><td>In a GIF animation, such images are usually frames which
4945 provide partial intermediary updates between the frames that are
4946 actually displayed to users. These frames are usually added for
4947 improved frame optimization in GIF animations. </td>
4948 </tr>
4949
4950 <tr>
4951 <td>trim-bounds</td>
4952 <td>Find the bounds of all the images in the current
4953 image sequence, then adjust the offsets so all images are contained on
4954 a minimal positive canvas. None of the image data is modified or
4955 merged, only the individual image virtual canvas size and offset.
4956 All the images is given the same canvas size, and and will have
4957 a positive offset, but will remain in the same position relative to
4958 each other. As a result of the minimal canvas size at least one image
4959 will touch every edge of that canvas. The image data touching those
4960 edges however may be transparent. </td>
4961 </tr>
4962
4963 <tr><td></td><td>The result is much like if you used 'merge' followed by a
4964 <a href="command-line-options.html#repage">+repage</a> option, except that all the images
4965 have been kept separate. If 'flatten' is used after using
4966 'trim-bounds' you will get the same result. </td>
4967 </tr>
4968
4969 </tbody>
4970</table>
4971
4972<p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
4973
4974<p>The operators <a href="command-line-options.html#coalesce">-coalesce</a>, <a href="command-line-options.html#deconstruct">-deconstruct</a>, <a href="command-line-options.html#flatten">-flatten</a>, and <a href="command-line-options.html#mosaic">-mosaic</a> are only aliases for the above methods and may be depreciated in
4975the future. Also see <a href="command-line-options.html#page">-page</a>, <a href="command-line-options.html#repage">-repage</a> operators, the <a href="command-line-options.html#compose">-compose</a> setting, and the
4976GIF <a href="command-line-options.html#dispose">-dispose</a> and <a href="command-line-options.html#delay">-delay</a>
4977settings. </p>
4978
4979
4980<div style="margin: auto;">
4981 <h3 class="magick-header"><a id="level"></a>-level <var>black_point</var>{,<var>white_point</var>}{<var>%</var>}{,<var>gamma</var>}</h3>
4982</div>
4983
4984<p class="magick-description">adjust the level of image channels.</p>
4985
4986<p>Given one, two or three values delimited with commas: black-point,
4987white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
4988white points range from 0 to <var>QuantumRange</var>, or from 0 to
4989100%; if the white point is omitted it is set to (<var>QuantumRange</var> - black_point), so as to center contrast changes.
4990If a <code>%</code> sign is present anywhere in the string, both black and white
4991points are percentages of the full color range. Gamma will do a <a href="command-line-options.html#gamma">-gamma</a> adjustment of the values. If it is omitted, the
4992default of 1.0 (no gamma correction) is assumed.</p>
4993
4994<p>In normal usage (<code>-level</code>) the image values are stretched so that
4995the given '<code>black_point</code>' value in the original image is set to zero
4996(or black), while the given '<code>white_point</code>' value is set to <var>QuantumRange</var> (or white). This provides you with direct
4997contrast adjustments to the image. The '<code>gamma</code>' of the resulting
4998image will then be adjusted. </p>
4999
5000<p>From ImageMagick v6.4.1-9 using the plus form of the operator
5001(<code>+level</code>) or adding the special '!' flag anywhere in the argument
5002list, will cause the operator to do the reverse of the level adjustment. That
5003is a zero, or <var>QuantumRange</var> value (black, and white, resp.)
5004in the original image, is adjusted to the given level values, allowing you to
5005de-contrast, or compress the channel values within the image. The
5006'<code>gamma</code>' is adjusted before the level adjustment to de-contrast the
5007image is made. </p>
5008
5009<p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
5010setting are adjusted (defaults to RGB color channels only), allowing you to
5011limit the effect of this operator. </p>
5012
5013<p>Please note that the transparency channel is treated as 'matte'
5014values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
5015
5016
5017<div style="margin: auto;">
5018 <h3 class="magick-header"><a id="level-colors"></a>-level-colors {<var>black_color</var>}{,}{<var>white_color</var>}</h3>
5019</div>
5020
5021<p class="magick-description">adjust the level of an image using the provided dash separated colors.</p>
5022
5023<p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
5024value value for each color channel is determined by the
5025'<code>black_color</code>' and '<code>white_color</code>' colors given (as
5026described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
5027
5028<p>This effectually means the colors provided to <code>-level-colors</code>
5029is mapped to become 'black' and 'white' respectively, with all the other
5030colors linearly adjusted (or clipped) to match that change. Each channel is
5031adjusted separately using the channel values of the colors specified. </p>
5032
5033<p>On the other hand the plus form of the operator (<code>+level-colors</code>)
5034will map the image color 'black' and 'white' to the given colors
5035respectively, resulting in a gradient (de-contrasting) tint of the image to
5036those colors. This can also be used to convert a plain gray-scale image into a
5037one using the gradient of colors specified. </p>
5038
5039<p>By supplying a single color with a comma separator either before or after
5040that color, will just replace the respective 'black' or 'white' point
5041respectively. But if no comma separator is provided, the given color is
5042used for both the black and white color points, making the operator either
5043threshold the images around that color (- form) or set all colors to that
5044color (+ form). </p>
5045
5046
5047<div style="margin: auto;">
5048 <h3 class="magick-header"><a id="limit"></a>-limit <var>type value</var></h3>
5049</div>
5050
5051<p class="magick-description">Set the pixel cache resource limit.</p>
5052
5053<p>Choose from: <code>area</code>, <code>disk</code>, <code>file</code>,
5054<code>map</code>, <code>memory</code>, <code>thread</code>, or <code>time</code>.</p>
5055
5056<p>The value for <code>file</code> is in number of files. The other limits are
5057in bytes. Define arguments for the memory, map, area, and disk resource limits
5058with SI prefixes (.e.g 100MB).</p>
5059
5060<p>By default the limits are 768 files, 3GB of image area, 1.5GiB memory, 3GiB
5061memory map, and 18.45EB of disk. These limits are adjusted relative to the
5062available resources on your computer if this information is available. When
5063any limit is reached, ImageMagick fails in some fashion but attempts to take
5064compensating actions, if possible. For example, the following limits
5065memory:</p>
5066
5067<pre>
5068-limit memory 32MiB -limit map 64MiB
5069</pre>
5070
5071<p>Use <a href="command-line-options.html#list">-list resource</a> to list the current limits. For example, our system shows these limits:</p>
5072
5073<pre>
5074-&gt; identify -list resource
5075Resource limits:
5076 Width: 100MP
5077 Height: 100MP
5078 Area: 25.181GB
5079 Memory: 11.726GiB
5080 Map: 23.452GiB
5081 Disk: unlimited
5082 File: 768
5083 Thread: 12
5084 Throttle: 0
5085 Time: unlimited
5086</pre>
5087
5088<p>Requests for pixel storage to keep intermediate images are satisfied by one
5089of three resource categories: in-memory pool, memory-mapped files pool, and
5090disk pool (in that order) depending on the <a href="command-line-options.html#limit">‑limit</a> settings
5091and whether the system honors a resource request. If the total size of
5092allocated pixel storage in the given pool reaches the corresponding limit, the
5093request is passed to the next pool. Additionally, requests that exceed the
5094<code>area</code> limit automagically are allocated on disk.</p>
5095
5096<p>To illustrate how ImageMagick utilizes resource limits, consider a typical
5097image resource request. First, ImageMagick tries to allocate the pixels in
5098memory. The request might be denied if the resource request exceeds the
5099<code>memory</code> limit or if the system does not honor the request. If
5100a memory request is not honored, the pixels are allocated to disk and the file
5101is memory-mapped. However, if the allocation request exceeds the
5102<code>map</code> limit, the resource allocation goes to disk. In all cases, if
5103the resource request exceeds the <code>area</code> limit, the pixels are
5104automagically cached to disk. If the disk has a hard limit, the program
5105fails.</p>
5106
5107<p>In most cases you simply do not need to concern yourself with resource
5108limits. ImageMagick chooses reasonable defaults and most images do not tax
5109your computer resources. Where limits do come in handy is when you process
5110images that are large or on shared systems where ImageMagick can consume all
5111or most of the available memory. In this case, the ImageMagick workflow slows
5112other processes or, in extreme cases, brings the system to a halt. Under
5113these circumstances, setting limits give some assurances that the ImageMagick
5114workflow will not interfere with other concurrent uses of the computer. For
5115example, assume you have a web interface that processes images uploaded from
5116the Internet. To assure ImageMagick does not exceed 10MiB of memory you can
5117simply set the area limit to 10MiB:</p>
5118
5119<pre>
5120-limit area 10MB
5121</pre>
5122
5123<p>Now whenever a large image is processed, the pixels are automagically
5124cached to disk instead of memory. This of course implies that large images
5125typically process very slowly, simply because pixel processing in memory can
5126be an order of magnitude faster than on disk. Because your web site users
5127might inadvertently upload a huge image to process, you should set a disk
5128limit as well:</p>
5129
5130<pre>
5131-limit area 10MB -limit disk 500MB
5132</pre>
5133
5134<p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
5135
5136<p>In addition to command-line resource limit option, resources can be set
5137with <a href="resources.html#environment">environment variables</a>. Set the
5138environment variables <code>MAGICK_AREA_LIMIT</code>,
5139<code>MAGICK_DISK_LIMIT</code>, <code>MAGICK_FILE_LIMIT</code>,
5140<code>MAGICK_MEMORY_LIMIT</code>, <code>MAGICK_MAP_LIMIT</code>,
5141<code>MAGICK_THREAD_LIMIT</code>, <code>MAGICK_TIME_LIMIT</code> for limits of
5142image area, disk space, open files, heap memory, memory map, number of threads
5143of execution, and maximum elapsed time in seconds respectively.</p>
5144
5145<p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
5146their commands and then scouring the generated output for references to the
5147pixel cache, in order to determine how the pixel cache was allocated and how
5148resources were consumed. Advanced Unix/Linux users can pipe that output
5149through <code>grep memory|open|destroy|disk</code> for more readable sifting.
5150</p>
5151
5152<p>For more about ImageMagick's use of resources, see the section <b>Cache
5153Storage and Resource Requirements</b> on the <a href="architecture.html#cache%0A">Architecture</a> page. </p>
5154
5155<div style="margin: auto;">
5156 <h3 class="magick-header"><a id="linear-stretch"></a>-linear-stretch <var>black-point</var><br>-linear-stretch <var>black-point</var>{x<var>white-point</var>}{<var>%</var>}}</h3>
5157</div>
5158
5159<p class="magick-description">Linear with saturation stretch.</p>
5160
5161<p>This is very similar to <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
5162and uses a 'histogram bin' to determine the range of color values that needs to
5163be stretched. However it then stretches those colors using the <a href="command-line-options.html#level">-level</a> operator.</p>
5164
5165<p>As such while the initial determination may have 'binning' round off
5166effects, the image colors are stretched mathematically, rather than using the
5167histogram bins. This makes the operator more accurate. </p>
5168
5169<p>note however that a <a href="command-line-options.html#linear-stretch">-linear-stretch</a> of
5170'<code>0</code>' does nothing, while a value of '<code>1</code>' does a near
5171perfect stretch of the color range. </p>
5172
5173<p>See also <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect'
5174normalization of mathematical images. </p>
5175
5176<p>This operator is under review for re-development. </p>
5177
5178
5179<div style="margin: auto;">
5180 <h3 class="magick-header"><a id="linewidth"></a>-linewidth</h3>
5181</div>
5182
5183<p class="magick-description">the line width for subsequent draw operations.</p>
5184
5185<div style="margin: auto;">
5186 <h3 class="magick-header"><a id="liquid-rescale"></a>-liquid-rescale <var>geometry</var></h3>
5187</div>
5188
5189<p class="magick-description">rescale image with seam-carving.</p>
5190
5191<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5192
5193<div style="margin: auto;">
5194 <h3 class="magick-header"><a id="list"></a>-list <var>type</var></h3>
5195</div>
5196
5197<p class="magick-description">Print a list of supported arguments for various options or settings. Choose from these list types:</p>
5198
5199<pre class="pre-scrollable">
5200Align
5201Alpha
5202Boolean
5203Cache
5204Channel
5205Class
5206ClipPath
5207Coder
5208Color
5209Colorspace
5210Command
5211Complex
5212Compose
5213Compress
5214Configure
5215DataType
5216Debug
5217Decoration
5218Delegate
5219Direction
5220Dispose
5221Distort
5222Dither
5223Endian
5224Evaluate
5225FillRule
5226Filter
5227Font
5228Format
5229Function
5230Gravity
5231Intensity
5232Intent
5233Interlace
5234Interpolate
5235Kernel
5236Layers
5237LineCap
5238LineJoin
5239List
5240Locale
5241LogEvent
5242Log
5243Magic
5244Method
5245Metric
5246Mime
5247Mode
5248Morphology
5249Module
5250Noise
5251Orientation
5252PixelIntensity
5253Policy
5254PolicyDomain
5255PolicyRights
5256Preview
5257Primitive
5258QuantumFormat
5259Resource
5260SparseColor
5261Statistic
5262Storage
5263Stretch
5264Style
5265Threshold
5266Type
5267Units
5268Validate
5269VirtualPixel
5270</pre>
5271
5272<p>These lists vary depending on your version of ImageMagick. Use "<code>-list
5273list</code>" to get a complete listing of all the "<code>-list</code>" arguments
5274available:</p>
5275
5276<pre>
5277identify -list list
5278</pre>
5279
5280<div style="margin: auto;">
5281 <h3 class="magick-header"><a id="log"></a>-log <var>string</var></h3>
5282</div>
5283
5284<p class="magick-description">Specify format for debug log.</p>
5285
5286<p>This option specifies the format for the log printed when the <a href="command-line-options.html#debug">-debug</a> option is active.</p>
5287
5288<p>You can display the following components by embedding special format
5289characters:</p>
5290
5291<dl class="dl-horizontal">
5292<dt>%d</dt><dd>domain</dd>
5293<dt>%e</dt><dd>event</dd>
5294<dt>%f</dt><dd>function</dd>
5295<dt>%l</dt><dd>line</dd>
5296<dt>%m</dt><dd>module</dd>
5297<dt>%p</dt><dd>process ID</dd>
5298<dt>%r</dt><dd>real CPU time</dd>
5299<dt>%t</dt><dd>wall clock time</dd>
5300<dt>%u</dt><dd>user CPU time</dd>
5301<dt>%%</dt><dd>percent sign</dd>
5302<dt>\n</dt><dd>newline</dd>
5303<dt>\r</dt><dd>carriage return</dd>
5304</dl>
5305
5306<p>For example:</p>
5307
5308<pre>
5309convert -debug coders -log "%u %m:%l %e" in.gif out.png
5310</pre>
5311
5312<p>The default behavior is to print all of the components.</p>
5313
5314<div style="margin: auto;">
5315 <h3 class="magick-header"><a id="loop"></a>-loop <var>iterations</var></h3>
5316</div>
5317
5318<p class="magick-description">add Netscape loop extension to your GIF animation.</p>
5319
5320<p>Set iterations to zero to repeat the animation an infinite number of times,
5321otherwise the animation repeats itself up to <var>iterations</var>
5322times.</p>
5323
5324<div style="margin: auto;">
5325 <h3 class="magick-header"><a id="lowlight-color"></a>-lowlight-color <var>color</var></h3>
5326</div>
5327
5328<p class="magick-description">when comparing images, de-emphasize pixel differences with this color.</p>
5329
5330<div style="margin: auto;">
5331 <h3 class="magick-header"><a id="magnify"></a>-magnify</h3>
5332</div>
5333
5334<p class="magick-description">double the size of the image with pixel art scaling.</p>
5335
5336
5337<div style="margin: auto;">
5338 <h3 class="magick-header"><a id="map"></a>-map <var>type</var></h3>
5339</div>
5340
5341<p class="magick-description">Display image using this <var>type</var>.</p>
5342
5343<p>Choose from these <var>Standard Colormap</var> types:</p>
5344
5345<pre>
5346best
5347default
5348gray
5349red
5350green
5351blue
5352</pre>
5353
5354<p>The <var>X server</var> must support the <var>Standard
5355Colormap</var> you choose, otherwise an error occurs. Use <code>list</code> as
5356the type and <code>display</code> searches the list of colormap types in
5357<code>top-to-bottom</code> order until one is located. See <var>xstdcmap(1)</var> for one way of creating Standard Colormaps.</p>
5358
5359
5360<div style="margin: auto;">
5361 <h3 class="magick-header"><a id="map_stream_"></a>-map <var>components</var></h3>
5362</div>
5363
5364<p class="magick-description">pixel map.</p>
5365
5366<p>Here are the valid components of a map:</p>
5367
5368<dl class="dl-horizontal">
5369<dt>r</dt><dd> red pixel component</dd>
5370<dt>g</dt><dd> green pixel component</dd>
5371<dt>b</dt><dd> blue pixel component</dd>
5372<dt>a</dt><dd> alpha pixel component (0 is transparent)</dd>
5373<dt>o</dt><dd> opacity pixel component (0 is opaque)</dd>
5374<dt>i</dt><dd> grayscale intensity pixel component</dd>
5375<dt>c</dt><dd> cyan pixel component</dd>
5376<dt>m</dt><dd> magenta pixel component</dd>
5377<dt>y</dt><dd> yellow pixel component</dd>
5378<dt>k</dt><dd> black pixel component</dd>
5379<dt>p</dt><dd> pad component (always 0)</dd>
5380</dl>
5381
5382<p>You can specify as many of these components as needed in any order (e.g.
5383bgr). The components can repeat as well (e.g. rgbr).</p>
5384
5385
5386<div style="margin: auto;">
5387 <h3 class="magick-header"><a id="mask"></a>-mask
5388<var>filename</var></h3>
5389</div>
5390
5391<p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
5392
5393<p>This the same as using a mask used for composite masking operations, with
5394grayscale values causing blended updates of the image the mask is attached to.
5395</p>
5396
5397<p>Use <a href="command-line-options.html#mask">+mask</a> to remove the mask from images.</p>
5398
5399<p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
5400but with strict boolean masking. </p>
5401
5402<div style="margin: auto;">
5403 <h3 class="magick-header"><a id="mattecolor"></a>-mattecolor <var>color</var></h3>
5404</div>
5405
5406<p class="magick-description">Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</p>
5407
5408<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5409
5410<p>The default matte color is <code>#BDBDBD</code>, <span style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5411
5412<div style="margin: auto;">
5413 <h3 class="magick-header"><a id="maximum"></a>-maximum</h3>
5414</div>
5415
5416<p class="magick-description">return the maximum intensity of an image sequence.</p>
5417
5418<p>Select the 'maximum' value from all the surrounding pixels. </p>
5419
5420<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5421name. </p>
5422
5423<div style="margin: auto;">
5424 <h3 class="magick-header"><a id="median"></a>-median <var>geometry</var></h3>
5425</div>
5426
5427<p class="magick-description">apply a median filter to the image.</p>
5428
5429<p>Select the 'middle' value from all the surrounding pixels. </p>
5430
5431<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5432name. </p>
5433
5434<div style="margin: auto;">
5435 <h3 class="magick-header"><a id="mean-shift"></a>-mean-shift <var>width</var>x<var>height</var>{<var>+distance</var>{%}}</h3>
5436</div>
5437
5438<p class="magick-description">image noise removal and color reduction/segmentation (e.g. -mean-shift 7x7+10%).</p>
5439
5440<p><var>width</var>x<var>height</var> is the window size and <var>distance</var> is the color distance measured in the range 0 to 1 or 0 to 100%</p>
5441
5442<p>The mean shift algorithm is iterative and thus slower the larger the window size. For each pixel, it gets all the pixels in the window centered at the pixel and excludes those that are outside the <var>radius=sqrt((width-1)(height-1)/4)</var> surrounding the pixel. From those pixels, it finds which of them are within the specified squared color distance from the current mean. It then computes a new x,y centroid from those coordinates and a new mean. This new x,y centroid is used as the center for a new window. This process is iterated until it converges and the final mean is then used to replace the original pixel value. It repeats this process for the next pixel, etc, until it processes all pixels in the image. Results are better when using other colorspaces rather than RGB. Recommend YIQ, YUV or YCbCr, which seem to give equivalent results.</p>
5443
5444<div style="margin: auto;">
5445 <h3 class="magick-header"><a id="metric"></a>-metric <var>type</var></h3>
5446</div>
5447
5448<p class="magick-description">Output to STDERR a measure of the differences between images according to the <var>type</var> given metric.</p>
5449
5450<p>Choose from:</p>
5451
5452<dl class="dl-horizontal">
5453<dt>AE</dt><dd> absolute error count, number of different pixels (-fuzz effected)</dd>
5454<dt>FUZZ</dt><dd> mean color distance</dd>
5455<dt>MAE</dt><dd> mean absolute error (normalized), average channel error distance</dd>
5456<dt>MEPP</dt><dd> mean error per pixel (normalized mean error, normalized peak error)</dd>
5457<dt>MSE</dt><dd> mean error squared, average of the channel error squared</dd>
5458<dt>NCC</dt><dd> normalized cross correlation</dd>
5459<dt>PAE</dt><dd> peak absolute (normalized peak absolute)</dd>
5460<dt>PHASH</dt><dd> perceptual hash</dd>
5461<dt>PSNR</dt><dd> peak signal to noise ratio</dd>
5462<dt>RMSE</dt><dd> root mean squared (normalized root mean squared)</dd>
5463</dl>
5464
5465<p>Control the '<code>AE</code>', or absolute count of pixels that are different,
5466with the <a href="command-line-options.html#fuzz">-fuzz</a> factor (ignore pixels which
5467only changed by a small amount). Use '<code>PAE</code>' to find the
5468size of the <a href="command-line-options.html#fuzz">-fuzz</a> factor needed to make all pixels
5469'similar', while '<code>MAE</code>' determines the factor needed
5470for about half the pixels to be similar. </p>
5471
5472<p>The '<code>MEPP</code>' metric returns three different metrics
5473('<code>MAE</code>', '<code>MAE</code>' normalized, and '<code>PAE</code>'
5474normalized) from a single comparison run. </p>
5475
5476<p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5477metric</a> option.</p>
5478
5479
5480<div style="margin: auto;">
5481 <h3 class="magick-header"><a id="minimum"></a>-minimum</h3>
5482</div>
5483
5484<p class="magick-description">return the minimum intensity of an image sequence.</p>
5485
5486<p>Select the 'minimal' value from all the surrounding pixels. </p>
5487
5488<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5489name. </p>
5490
5491
5492
5493<div style="margin: auto;">
5494 <h3 class="magick-header"><a id="mode"></a>-mode <var>geometry</var></h3>
5495</div>
5496
5497<p class="magick-description">make each pixel the \'predominant color\' of the neighborhood.'</p>
5498
5499<div style="margin: auto;">
5500 <h3 class="magick-header">-mode <var>value</var></h3>
5501</div>
5502
5503<p class="magick-description">Mode of operation.</p>
5504
5505<p>Choose the <var>value</var> from these styles: <code>Frame,
5506Unframe, or Concatenate</code></p>
5507
5508<p>Use the <a href="command-line-options.html#list">-list</a> option with a '<code>Mode</code>' argument
5509for a list of <a href="command-line-options.html#mode">-mode</a> arguments available in your
5510ImageMagick installation.</p>
5511
5512
5513<div style="margin: auto;">
5514 <h3 class="magick-header"><a id="modulate"></a>-modulate <var>brightness</var>[,<var>saturation</var>,<var>hue</var>]</h3>
5515</div>
5516
5517<p class="magick-description">Vary the <var>brightness</var>, <var>saturation</var>, and <var>hue</var> of an image.</p>
5518
5519<p>The arguments are given as a percentages of variation. A value of 100 means
5520no change, and any missing values are taken to mean 100.</p>
5521
5522<p>The <var>brightness</var> is a multiplier of the overall
5523brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5524twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5525before and after. </p>
5526
5527<p>The <var>saturation</var> controls the amount of color in an
5528image. For example, 0 produce a grayscale image, while a large value such as
5529200 produce a very colorful, 'cartoonish' color.</p>
5530
5531<p>The <var>hue</var> argument causes a "rotation" of the colors
5532within the image by the amount specified. For example, 50 results in
5533a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5534A value of either 0 or 200 results in a complete 180 degree rotation of the
5535image. Using a value of 300 is a 360 degree rotation resulting in no change to
5536the original image. </p>
5537
5538<p>For example, to increase the color brightness by 20% and decrease the color
5539saturation by 10% and leave the hue unchanged, use <a href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5540
5541<p>Use <a href="command-line-options.html#set">-set</a> attribute of '<code>option:modulate:colorspace</code>' to specify which colorspace to
5542modulate. Choose from <code>HCL</code>, <code>HCLp</code>, <code>HSB</code>, <code>HSI</code>, <code>HSL</code> (the default), <code>HSV</code>, <code>HWB</code>, or <code>LCH</code> (LCHuv). For example,</p>
5543
5544<pre>
5545convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png
5546</pre>
5547
5548<div style="margin: auto;">
5549 <h3 class="magick-header"><a id="moments"></a>-moments</h3>
5550</div>
5551
5552<p class="magick-description">report image moments and perceptual hash.</p>
5553
5554
5555<div style="margin: auto;">
5556 <h3 class="magick-header"><a id="monitor"></a>-monitor</h3>
5557</div>
5558
5559<p class="magick-description">monitor progress.</p>
5560
5561
5562<div style="margin: auto;">
5563 <h3 class="magick-header"><a id="monochrome"></a>-monochrome</h3>
5564</div>
5565
5566<p class="magick-description">transform the image to black and white.</p>
5567
5568<div style="margin: auto;">
5569 <h3 class="magick-header"><a id="morph"></a>-morph <var>frames</var></h3>
5570</div>
5571
5572<p class="magick-description">morphs an image sequence.</p>
5573
5574<p>Both the image pixels and size are linearly interpolated to give the
5575appearance of a metamorphosis from one image to the next, over all the images
5576in the current image list. The added images are the equivalent of a <a href="command-line-options.html#blend">-blend</a> composition. The <var>frames</var>
5577argument determine how many images to interpolate between each image. </p>
5578
5579
5580<div style="margin: auto;">
5581 <h3 class="magick-header"><a id="morphology"></a>-morphology</h3>
5582 <h3 class="magick-header">-morphology <var>method</var> <var>kernel</var></h3>
5583</div>
5584
5585<p class="magick-description">apply a morphology method to the image.</p>
5586
5587<p>Until I get around to writing an option summary for this, see <a href="http://www.imagemagick.org/Usage/morphology/">IM Usage Examples,
5588Morphology</a>. </p>
5589
5590
5591<div style="margin: auto;">
5592 <h3 class="magick-header"><a id="mosaic"></a>-mosaic</h3>
5593</div>
5594
5595<p class="magick-description">an simple alias for the <a href="command-line-options.html#layers">-layers</a> method "mosaic"</p>
5596
5597
5598<div style="margin: auto;">
5599 <h3 class="magick-header"><a id="motion-blur"></a>-motion-blur <var>radius</var><br>-motion-blur <var>radius</var>x<var>sigma</var>+<var>angle</var></h3>
5600</div>
5601
5602<p class="magick-description">simulate motion blur.</p>
5603
5604<p>Blur with the given radius, standard deviation (sigma), and angle. The
5605angle given is the angle toward which the image is blurred. That is the
5606direction people would consider the object is coming from. </p>
5607
5608<p>Note that the blur is not uniform distribution, giving the motion a
5609definite sense of direction of movement. </p>
5610
5611<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5612pixels which are outside the image proper are blurred into the final result.
5613</p>
5614
5615<div style="margin: auto;">
5616 <h3 class="magick-header"><a id="name"></a>-name</h3>
5617</div>
5618
5619<p class="magick-description">name an image.</p>
5620<div style="margin: auto;">
5621 <h3 class="magick-header"><a id="negate"></a>-negate</h3>
5622</div>
5623
5624<p class="magick-description">replace each pixel with its complementary color.</p>
5625
5626<p>The red, green, and blue intensities of an image are negated. White becomes
5627black, yellow becomes blue, etc. Use <a href="command-line-options.html#negate">+negate</a> to only
5628negate the grayscale pixels of the image.</p>
5629
5630<div style="margin: auto;">
5631 <h3 class="magick-header"><a id="noise"></a>-noise <var>geometry</var><br>
5632 +noise <var>type</var></h3>
5633</div>
5634
5635<p class="magick-description">Add or reduce noise in an image.</p>
5636
5637<p>The principal function of noise peak elimination filter is to smooth the
5638objects within an image without losing edge information and without creating
5639undesired structures. The central idea of the algorithm is to replace a pixel
5640with its next neighbor in value within a pixel window, if this pixel has been
5641found to be noise. A pixel is defined as noise if and only if this pixel is
5642a maximum or minimum within the pixel window.</p>
5643
5644<p>Use <code><a href="command-line-options.html#noise">-noise</a> <var>radius</var></code> to
5645specify the width of the neighborhood when reducing noise. This is equivalent
5646to using a <code><a href="command-line-options.html#statistic">-statistic</a> NonPeak</code> operation,
5647which should be used in preference.</p>
5648
5649<p>Use <a href="command-line-options.html#noise">+noise</a> followed by a noise <var>type</var> to add noise to an image. Choose from these noise
5650types:</p>
5651
5652<pre>
5653Gaussian
5654Impulse
5655Laplacian
5656Multiplicative
5657Poisson
5658Random
5659Uniform
5660</pre>
5661
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]5662<p>The amount of noise added can be controled by the <code><a href="command-line-options.html#attenuate">-attenuate</a></code> setting. If unset the value is
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]5663equivalent to 1.0, or a maximum noise addition.</p>
5664
5665<p>Note that Random will replace the image with noise rather than add noise to the image. Use Uniform, if you wish to add random noise to the image.</p>
5666
5667<p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
5668
5669<p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
5670the use of a controlling value to specify the amount of noise that should be
5671added to an image. </p>
5672
5673
5674<div style="margin: auto;">
5675 <h3 class="magick-header"><a id="normalize"></a>-normalize</h3>
5676</div>
5677
5678<p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
5679
5680<p>The intensity values are stretched to cover the entire range of possible
5681values. While doing so, black-out at most <var>2%</var> of the pixels and
5682white-out at most <var>1%</var> of the pixels.</p>
5683
5684<p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize">-normalize</a>
5685is equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x1%</a>.
5686(Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x99%</a>).</p>
5687
5688<p>All the channels are normalized in concert by the came amount so as to
5689preserve color integrity, when the default <a href="command-line-options.html#channel">+channel</a>
5690setting is in use. Specifying any other <a href="command-line-options.html#channel">-channel</a>
5691setting will normalize the RGB channels independently.</p>
5692
5693<p>See <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> for more details.
5694Also see <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect' normalization
5695that is better suited to mathematically generated images. </p>
5696
5697<p>This operator is under review for re-development. </p>
5698
5699
5700<div style="margin: auto;">
5701 <h3 class="magick-header"><a id="opaque"></a>-opaque <var>color</var></h3>
5702</div>
5703
5704<p class="magick-description">change this color to the fill color within the image.</p>
5705
5706<p>The <var>color</var> argument is defined using the format
5707described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz">-fuzz</a> setting can be used to match and replace colors similar to the one
5708given.</p>
5709
5710<p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
5711the target color. </p>
5712
5713<p>The <a href="command-line-options.html#transparent">-transparent</a> operator is exactly the same
5714as <a href="command-line-options.html#opaque">-opaque</a> but replaces the matching color with
5715transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
5716To ensure that it can do this it also ensures that the image has an alpha
5717channel enabled, as per "<code><a href="command-line-options.html#alpha">-alpha</a> set</code>", for
5718the new transparent colors, and does not require you to modify the <a href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
5719
5720
5721<div style="margin: auto;">
5722 <h3 class="magick-header"><a id="ordered-dither"></a>-ordered-dither <var>threshold_map</var>{,<var>level</var>...}</h3>
5723</div>
5724
5725<p class="magick-description">dither the image using a pre-defined ordered dither <var>threshold map</var> specified, and a uniform color map with the
5726given number of <var>levels</var> per color channel.</p>
5727
5728<p>You can choose from these standard threshold maps:</p>
5729
5730<pre class="pre-scrollable">
5731threshold 1x1 Threshold 1x1 (non-dither)
5732checks 2x1 Checkerboard 2x1 (dither)
5733o2x2 2x2 Ordered 2x2 (dispersed)
5734o3x3 3x3 Ordered 3x3 (dispersed)
5735o4x4 4x4 Ordered 4x4 (dispersed)
5736o8x8 8x8 Ordered 8x8 (dispersed)
5737h3x4a 4x1 Halftone 4x4 (angled)
5738h6x6a 6x1 Halftone 6x6 (angled)
5739h8x8a 8x1 Halftone 8x8 (angled)
5740h3x4o Halftone 4x4 (orthogonal)
5741h6x6o Halftone 6x6 (orthogonal)
5742h8x8o Halftone 8x8 (orthogonal)
5743h36x16o Halftone 16x16 (orthogonal)
5744c5x5b c5x5 Circles 5x5 (black)
5745c5x5w Circles 5x5 (white)
5746c6x6b c6x6 Circles 6x6 (black)
5747c6x6w Circles 6x6 (white)
5748c7x7b c7x7 Circles 7x7 (black)
5749c7x7w Circles 7x7 (white)
5750</pre>
5751
5752<p> The <code>threshold</code> generated a simple 50% threshold of the image.
5753This could be used with <var>level</var> to do the equivalent of <a href="command-line-options.html#posterize">-posterize</a> to reduce an image to basic primary colors.
5754</p>
5755
5756<p>The <code>checks</code> pattern produces a 3 level checkerboard dither
5757pattern. That is a grayscale will become a pattern of solid black, solid
5758white, and mid-tone colors into a checkerboard pattern of black and white.
5759</p>
5760
5761<p>You can define your own <var>threshold map</var> for ordered
5762dithering and halftoning your images, in either personal or system
5763<code>thresholds.xml</code> XML file. See <a href="resources.html">Resources</a>
5764for more details of configuration files. </p>
5765
5766<p>To print a complete list of the thresholds that have been defined, use the
5767<a href="command-line-options.html#list">-list threshold</a> option.</p>
5768
5769<p>Note that at this time the same threshold dithering map is used for all
5770color channels, no attempt is made to offset or rotate the map for different
5771channels is made, to create an offset printing effect. Also as the maps are
5772simple threshold levels, the halftone and circle maps will create incomplete
5773circles along the edges of a colored area. Also all the effects are purely
5774on/off boolean effects, without anti-aliasing to make the circles smooth
5775looking. Large dots can be made to look better with a small amount of blurring
5776after being created. </p>
5777
5778
5779<div style="margin: auto;">
5780 <h3 class="magick-header"><a id="orient"></a>-orient <var>image orientation</var></h3>
5781</div>
5782
5783<p class="magick-description">specify orientation of a digital camera image.</p>
5784
5785<p>Choose from these orientations:</p>
5786
5787<pre>
5788bottom-left right-top
5789bottom-right top-left
5790left-bottom top-right
5791left-top undefined
5792right-bottom
5793</pre>
5794
5795<p>To print a complete list of orientations, use the <a href="command-line-options.html#list">-list
5796orientation</a> option.</p>
5797
5798
5799<div style="margin: auto;">
5800 <h3 class="magick-header"><a id="page"></a>-page <var>geometry</var><br>
5801 -page <var>media</var>[<var>offset</var>][{<var>^!&lt;&gt;</var>}]<br>
5802 +page
5803 </h3>
5804</div>
5805
5806<p class="magick-description">Set the size and location of an image on the larger virtual canvas.</p>
5807
5808<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5809
5810<p>For convenience you can specify the page size using <var>media</var> (see below). Offsets can then be added as with other
5811<var>geometry</var> arguments (e.g. <a href="command-line-options.html#page">-page</a> <code>Letter+43+43</code>).</p>
5812
5813<p>Use <var>media</var> as shorthand to specify the dimensions (<var>width</var>x<var>height</var>) of the <var>PostScript</var> page in dots per inch or a TEXT page in pixels.
5814The choices for a PostScript page are:</p>
5815
5816<dl class="dl-horizontal">
5817<dt> 11x17 </dt> <dd> 792 x 1224</dd>
5818<dt> Ledger </dt> <dd> 1224 x 792</dd>
5819<dt> Legal </dt> <dd> 612 x 1008</dd>
5820<dt> Letter </dt> <dd> 612 x 792</dd>
5821<dt> LetterSmall</dt> <dd> 612 x 792</dd>
5822<dt> ArchE </dt> <dd> 2592 x 3456</dd>
5823<dt> ArchD </dt> <dd> 1728 x 2592</dd>
5824<dt> ArchC </dt> <dd> 1296 x 1728</dd>
5825<dt> ArchB </dt> <dd> 864 x 1296</dd>
5826<dt> ArchA </dt> <dd> 648 x 864</dd>
5827<dt> A0 </dt> <dd> 2380 x 3368</dd>
5828<dt> A1 </dt> <dd> 1684 x 2380</dd>
5829<dt> A2 </dt> <dd> 1190 x 1684</dd>
5830<dt> A3 </dt> <dd> 842 x 1190</dd>
5831<dt> A4 </dt> <dd> 595 x 842</dd>
5832<dt> A4Small </dt> <dd> 595 x 842</dd>
5833<dt> A5 </dt> <dd> 421 x 595</dd>
5834<dt> A6 </dt> <dd> 297 x 421</dd>
5835<dt> A7 </dt> <dd> 210 x 297</dd>
5836<dt> A8 </dt> <dd> 148 x 210</dd>
5837<dt> A9 </dt> <dd> 105 x 148</dd>
5838<dt> A10 </dt> <dd> 74 x 105</dd>
5839<dt> B0 </dt> <dd> 2836 x 4008</dd>
5840<dt> B1 </dt> <dd> 2004 x 2836</dd>
5841<dt> B2 </dt> <dd> 1418 x 2004</dd>
5842<dt> B3 </dt> <dd> 1002 x 1418</dd>
5843<dt> B4 </dt> <dd> 709 x 1002</dd>
5844<dt> B5 </dt> <dd> 501 x 709</dd>
5845<dt> C0 </dt> <dd> 2600 x 3677</dd>
5846<dt> C1 </dt> <dd> 1837 x 2600</dd>
5847<dt> C2 </dt> <dd> 1298 x 1837</dd>
5848<dt> C3 </dt> <dd> 918 x 1298</dd>
5849<dt> C4 </dt> <dd> 649 x 918</dd>
5850<dt> C5 </dt> <dd> 459 x 649</dd>
5851<dt> C6 </dt> <dd> 323 x 459</dd>
5852<dt> Flsa </dt> <dd> 612 x 936</dd>
5853<dt> Flse </dt> <dd> 612 x 936</dd>
5854<dt> HalfLetter </dt> <dd> 396 x 612</dd>
5855</dl>
5856
5857<p>This option is also used to place subimages when writing to a multi-image
5858format that supports offsets, such as GIF89 and MNG. When used for this
5859purpose the offsets are always measured from the top left corner of the canvas
5860and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
5861position a GIF or MNG image, use <a href="command-line-options.html#page">-page</a><var>{+-}x{+-}y</var> (e.g. -page +100+200). When writing to a MNG
5862file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
5863the sequence with nonzero width and height defines the width and height values
5864that are written in the <code>MHDR</code> chunk. Otherwise, the MNG width and
5865height are computed from the bounding box that contains all images in the
5866sequence. When writing a GIF89 file, only the bounding box method is used to
5867determine its dimensions.</p>
5868
5869<p>For a PostScript page, the image is sized as in <a href="command-line-options.html#geometry">-geometry</a> but positioned relative to the <var>lower
5870left-hand corner</var> of the page by {+-}<code>x</code><var>offset</var>{+-}<code>y</code> <var>offset</var>. Use <a href="command-line-options.html#page">-page 612x792</a>, for example, to center the image within the
5871page. If the image size exceeds the PostScript page, it is reduced to fit the
5872page. The default gravity for the <a href="command-line-options.html#page">-page</a> option is <var>NorthWest</var>, i.e., positive <code>x</code> and <code>y</code> <var>offset</var> are measured rightward and downward from the top left
5873corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
5874present with a value other than <var>NorthWest</var>.</p>
5875
5876<p>The default page dimensions for a TEXT image is 612x792.</p>
5877
5878<p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
5879
5880<p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
5881
5882<div style="margin: auto;">
5883 <h3 class="magick-header"><a id="paint"></a>-paint <var>radius</var></h3>
5884</div>
5885
5886<p class="magick-description">simulate an oil painting.</p>
5887
5888<p>Each pixel is replaced by the most frequent color in a circular
5889neighborhood whose width is specified with <var>radius</var>.</p>
5890
5891<div style="margin: auto;">
5892 <h3 class="magick-header"><a id="path"></a>-path <var>path</var></h3></div>
5893
5894<p class="magick-description">write images to this path on disk.</p>
5895
5896<div style="margin: auto;">
5897 <h3 class="magick-header"><a id="pause_animate_"></a>-pause <var>seconds</var></h3>
5898</div>
5899
5900<p class="magick-description">Pause between animation loops</p>
5901
5902<p>Pause for the specified number of seconds before repeating the animation.</p>
5903
5904<div style="margin: auto;">
5905 <h3 class="magick-header"><a id="pause_import_"></a>-pause <var>seconds</var></h3>
5906</div>
5907
5908<p class="magick-description">Pause between snapshots.</p>
5909
5910<p>Pause for the specified number of seconds before taking the next snapshot.</p>
5911
5912<div style="margin: auto;">
5913 <h3 class="magick-header"><a id="perceptible"></a>-perceptible <var>epsilon</var></h3>
5914</div>
5915
5916<p class="magick-description">set each pixel whose value is less than |<var>epsilon</var>| to <var>-epsilon</var> or <var>epsilon</var> (whichever is closer) otherwise the pixel value remains unchanged.</p>
5917
5918<div style="margin: auto;">
5919 <h3 class="magick-header"><a id="ping"></a>-ping</h3>
5920</div>
5921
5922<p class="magick-description">efficiently determine image characteristics.</p>
5923
5924<div style="margin: auto;">
5925 <h3 class="magick-header"><a id="pointsize"></a>-pointsize <var>value</var></h3>
5926</div>
5927
5928<p class="magick-description">pointsize of the PostScript, OPTION1, or TrueType font.</p>
5929
5930<div style="margin: auto;">
5931 <h3 class="magick-header"><a id="polaroid"></a>-polaroid <var>angle</var></h3>
5932</div>
5933
5934<p class="magick-description">simulate a Polaroid picture.</p>
5935
5936<p>Use <code>+polaroid</code> to rotate the image at a random angle between -15 and +15 degrees.</p>
5937
5938<div style="margin: auto;">
5939 <h3 class="magick-header"><a id="poly"></a>-poly <var>"wt,exp ..."</var></h3>
5940</div>
5941
5942<p class="magick-description">combines multiple images according to a weighted sum of polynomials; one floating point weight (coefficient) and one floating point polynomial exponent (power) for each image expressed as comma separated pairs.</p>
5943
5944<p> The weights should typically be fractions between -1 and 1. But the sum of weights should be 1 or at least between 0 and 1 to avoid clamping in non-hdri mode at black and white.</p>
5945
5946<p>The exponents may be positive, negative or zero. A negative exponent is equivalent to 1 divided by the image raised to the corresponding positive exponent. A zero exponent always produces 1 scaled by quantumrange to white, i.e. wt*white, no matter what the image.</p>
5947
5948<p>The format is: <var>output = wt1*image1^exp1 + wt2*image2^exp2 </var>...</p>
5949
5950<p>Some simple uses are:</p>
5951<ul>
5952<li>A weighted sum of each image provided all weights add to unity and all exponents=1. If the the weights are all equal to 1/(number of images), then this is equivalent to <a href="command-line-options.html#profile">-evaluate-sequence</a> <var>mean</var>.</li>
5953<li>The sum of squares of two or more images, provided the weights are equal (and sum to 1 to avoid clamping) and the exponents equal 2.</li>
5954</ul>
5955
5956<p>Note that one may add a constant color to the expression simply by using xc:somecolor for one of the images and specifying the desired weight and exponent equal to 0.</p>
5957
5958<p>Similarly one may add white to the expression by simply using null: (or xc:white) for one of the images with the appropriate weight and exponent equal to 0.</p>
5959
5960
5961<div style="margin: auto;">
5962 <h3 class="magick-header"><a id="posterize"></a>-posterize <var>levels</var></h3>
5963</div>
5964
5965<p class="magick-description">reduce the image to a limited number of color levels per channel.</p>
5966
5967<p>Very low values of <var>levels</var>, e.g., 2, 3, 4, have the most
5968visible effect.</p>
5969
5970<div style="margin: auto;">
5971 <h3 class="magick-header"><a id="precision"></a>-precision <var>value</var></h3>
5972</div>
5973
5974<p class="magick-description">set the maximum number of significant digits to be printed.</p>
5975
5976<div style="margin: auto;">
5977 <h3 class="magick-header"><a id="preview"></a>-preview <var>type</var></h3>
5978</div>
5979
5980<p class="magick-description">image preview type.</p>
5981
5982<p>Use this option to affect the preview operation of an image (e.g.
5983<code>convert file.png -preview Gamma Preview:gamma.png</code>). Choose from
5984these previews:</p>
5985
5986<pre class="pre-scrollable">
5987AddNoise
5988Blur
5989Brightness
5990Charcoal
5991Despeckle
5992Dull
5993EdgeDetect
5994Gamma
5995Grayscale
5996Hue
5997Implode
5998JPEG
5999OilPaint
6000Quantize
6001Raise
6002ReduceNoise
6003Roll
6004Rotate
6005Saturation
6006Segment
6007Shade
6008Sharpen
6009Shear
6010Solarize
6011Spiff
6012Spread
6013Swirl
6014Threshold
6015Wave
6016</pre>
6017
6018<p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
6019
6020<p>The default preview is <code>JPEG</code>.</p>
6021
6022<div style="margin: auto;">
6023 <h3 class="magick-header"><a id="print"></a>-print <var>string</var></h3>
6024</div>
6025
6026<p class="magick-description">interpret string and print to console.</p>
6027
6028<div style="margin: auto;">
6029 <h3 class="magick-header"><a id="process"></a>-process <var>command</var></h3>
6030</div>
6031
6032<p class="magick-description">process the image with a custom image filter.</p>
6033
6034<p>The command arguments has the form <code>"module arg1 arg2 arg3 ...
6035argN"</code> where <code>module</code> is the name of the module to invoke (e.g.
6036"Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
6037pass to the process module.</p>
6038
6039<div style="margin: auto;">
6040 <h3 class="magick-header"><a id="profile"></a>-profile <var>filename</var><br>
6041 +profile <var>profile_name</var></h3>
6042</div>
6043
6044<p class="magick-description">Manage ICM, IPTC, or generic profiles in an image.</p>
6045
6046<p>Using <a href="command-line-options.html#profile">-profile</a> <var>filename</var> adds an
6047ICM (ICC color management), IPTC (newswire information), or a generic profile
6048to the image.</p>
6049
6050<p>Use <a href="command-line-options.html#profile">+profile <var>profile_name</var></a> to
6051remove the indicated profile. ImageMagick uses standard filename globbing, so
6052wildcard expressions may be used to remove more than one profile. Here we
6053remove all profiles from the image except for the XMP profile: <code>+profile
6054"!xmp,*"</code>. </p>
6055
6056<p>Use <code>identify -verbose</code> to find out which profiles are in the
6057image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
6058comments).</p>
6059
6060<p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
6061used. Instead, simply write the file to an image format such as <var>APP1, 8BIM, ICM,</var> or <var>IPTC</var>.</p>
6062
6063<p>For example, to extract the Exif data (which is stored in JPEG files in the
6064<var>APP1</var> profile), use.</p>
6065
6066<pre>
6067convert cockatoo.jpg profile.exif
6068</pre>
6069
6070<p>It is important to note that results may depend on whether or not the
6071original image already has an included profile. Also, keep in mind that <a href="command-line-options.html#profile">-profile</a> is an "operator" (as opposed to a "setting") and
6072therefore a conversion is made each time it is encountered, in order, in the
6073command-line. For instance, in the following example, if the original image is
6074CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
6075
6076<pre>
6077convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff
6078</pre>
6079
6080<p>Furthermore, since ICC profiles are not necessarily symmetric, extra
6081conversion steps can yield unwanted results. CMYK profiles are often very
6082asymmetric since they involve 3−&gt;4 and 4−&gt;3 channel mapping.
6083</p>
6084
6085<div style="margin: auto;">
6086 <h3 class="magick-header"><a id="quality"></a>-quality <var>value</var></h3>
6087</div>
6088
6089<p class="magick-description">JPEG/MIFF/PNG compression level.</p>
6090
6091<p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
6092highest compression) to 100 (best quality but least effective compression).
6093The default is to use the estimated quality of your input image if it can
6094be determined, otherwise 92. When the quality is greater than 90, then the
6095chroma channels are not downsampled.
6096Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
6097factors for chroma downsampling.</p>
6098
6099<p>For the JPEG-2000 image format, quality is mapped using a non-linear
6100equation to the compression ratio required by the Jasper library. This
6101non-linear equation is intended to loosely approximate the quality provided by
6102the JPEG v1 format. The default quality value 100, a request for non-lossy
6103compression. A quality of 75 results in a request for 16:1 compression.</p>
6104
6105<p>For the MNG and PNG image formats, the quality value sets the zlib
6106compression level (quality / 10) and filter-type (quality % 10). The default
6107PNG "quality" is 75, which means compression level 7 with adaptive PNG
6108filtering, unless the image has a color map, in which case it means
6109compression level 7 with no PNG filtering.</p>
6110
6111<p>For compression level 0 (quality value less than 10), the Huffman-only
6112strategy is used, which is fastest but not necessarily the worst
6113compression.</p>
6114
6115<p>If filter-type is 4 or less, the specified PNG filter-type is used for
6116all scanlines:</p>
6117
6118<dl class="dl-horizontal">
6119<dt>0</dt><dd>none</dd>
6120<dt>1</dt><dd>sub</dd>
6121<dt>2</dt><dd>up</dd>
6122<dt>3</dt><dd>average</dd>
6123<dt>4</dt><dd>Paeth</dd>
6124</dl>
6125
6126<p>If filter-type is 5, adaptive filtering is used when quality is greater
6127than 50 and the image does not have a color map, otherwise no filtering is
6128used.</p>
6129
6130<p>If filter-type is 6, adaptive filtering
6131with <var>minimum-sum-of-absolute-values</var> is used.</p>
6132
6133<p>Only if the output is MNG, if filter-type is 7, the LOCO color
6134transformation (intrapixel differencing) and adaptive filtering
6135with <var>minimum-sum-of-absolute-values</var> are used.</p>
6136
6137<p>If the filter-type is 8 the zlib Z_RLE compression strategy (or the
6138Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6139adaptive PNG filtering.</p>
6140
6141<p>If the filter-type is 9 the zlib Z_RLE compression strategy (or the
6142Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6143no PNG filtering.</p>
6144
6145<p>The quality setting has no effect on the appearance or signature of PNG
6146and MNG images, since the compression is always lossless.</p>
6147
6148<p>Not all combinations of compression level, strategy, and PNG filter type
6149can be obtained using the -quality option. For more precise control,
6150you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
6151PNG:compression-filter=N defines, respectively, instead.
6152See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
6153over values from the -quality option.</p>
6154
6155<p>For further information, see
6156the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
6157
6158<p>For the MIFF and TIFF image formats, quality/10 is the <a href="command-line-options.html#compress">Zip/BZip</a> compression level, which is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect on the image appearance, since the compression is always lossless.</p>
6159
6160<p>For the BPG image format, quality/2 is the actual BPG compression level (range from 0 to 51).</p>
6161
6162<div style="margin: auto;">
6163 <h3 class="magick-header"><a id="quantize"></a>-quantize <var>colorspace</var></h3>
6164</div>
6165
6166<p class="magick-description">reduce colors using this colorspace.</p>
6167
6168<p>This setting defines the colorspace used to sort out and reduce the number
6169of colors needed by an image (for later dithering) by operators such as <a href="command-line-options.html#colors">-colors</a>, Note that color reduction also happens
6170automatically when saving images to color-limited image file formats, such as
6171GIF, and PNG8.</p>
6172
6173
6174<div style="margin: auto;">
6175 <h3 class="magick-header"><a id="quiet"></a>-quiet</h3>
6176</div>
6177
6178<p class="magick-description">suppress all warning messages. Error messages are still reported.</p>
6179
6180<div style="margin: auto;">
6181 <h3 class="magick-header"><a id="radial-blur"></a>-radial-blur <var>angle</var></h3>
6182</div>
6183
6184<p class="magick-description">Blur around the center of the image.</p>
6185
6186<p>Note that this is actually a rotational blur rather than a radial and as
6187such actually mis-named. </p>
6188
6189<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
6190pixels which are outside the image proper are blurred into the final result.
6191</p>
6192
6193
6194<div style="margin: auto;">
6195 <h3 class="magick-header"><a id="raise"></a>-raise <var>thickness</var></h3>
6196</div>
6197
6198<p class="magick-description">Lighten or darken image edges.</p>
6199
6200<p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
6201a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>. </p>
6202
6203<p>Unlike the similar <a href="command-line-options.html#frame">-frame</a> option, <a href="command-line-options.html#raise">-raise</a> does not alter the dimensions of the image.</p>
6204
6205<div style="margin: auto;">
6206 <h3 class="magick-header"><a id="random-threshold"></a>-random-threshold <var>low</var>x<var>high</var></h3>
6207</div>
6208
6209<p class="magick-description">Apply a random threshold to the image.</p>
6210
6211<div style="margin: auto;">
6212 <h3 class="magick-header"><a id="red-primary"></a>-red-primary <var>x,y</var></h3>
6213</div>
6214
6215<p class="magick-description">Set the red chromaticity primary point.</p>
6216
6217<div style="margin: auto;">
6218 <h3 class="magick-header"><a id="regard-warnings"></a>-regard-warnings</h3>
6219</div>
6220
6221<p class="magick-description">Pay attention to warning messages.</p>
6222
6223<p>This option causes some warnings in some image formats to be treated
6224as errors. </p>
6225
6226<div style="margin: auto;">
6227 <h3 class="magick-header"><a id="remap"></a>-remap <var>filename</var></h3>
6228</div>
6229
6230<p class="magick-description">Reduce the number of colors in an image to the colors used by this image.</p>
6231
6232<p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
6233the given colors are dithered over the image as necessary, otherwise the closest
6234color (in RGB colorspace) is selected to replace that pixel in the image. </p>
6235
6236<p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
6237images in the current image sequence, all the images will have the same color
6238table. That means that when saved to a file format such as GIF, it will use
6239that color table as a single common or global color table, for all the images,
6240without requiring extra local color tables. </p>
6241
6242<p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
6243sequence to use a common color map over all the images. This equivalent to
6244appending all the images together (without extra background colors) and color
6245reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
6246limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
6247images. This ensures all the images follow a single color map. </p>
6248
6249<p>If the number of colors over all the images is less than 256, then <a href="command-line-options.html#remap">+remap</a> should not perform any color reduction or dithering, as
6250no color changes are needed. In that case, its only effect is to force the use
6251of a global color table. This recommended after using either <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to
6252reduce the number of colors in an animated image sequence. </p>
6253
6254<p>Note, the remap image colormap has at most 8-bits of precision. Deeper color maps are automagically coalesced with other colors to meet this requirement.</p>
6255
6256<div style="margin: auto;">
6257 <h3 class="magick-header"><a id="region"></a>-region <var>geometry</var></h3>
6258</div>
6259
6260<p class="magick-description">Set a region in which subsequent operations apply.</p>
6261
6262<p>The <var>x</var> and <var>y</var> offsets are treated
6263in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
6264
6265<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6266
6267<div style="margin: auto;">
6268 <h3 class="magick-header"><a id="remote"></a>-remote</h3>
6269</div>
6270
6271<p class="magick-description">perform a remote operation.</p>
6272
6273<p>The only command recognized is the name of an image file to load.</p>
6274
6275<p>If you have more than one <a href="display.html">display</a> application
6276running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
6277specify which application to control.</p>
6278
6279<div style="margin: auto;">
6280 <h3 class="magick-header"><a id="render"></a>-render</h3>
6281</div>
6282
6283<p class="magick-description">render vector operations.</p>
6284
6285<p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
6286This useful when saving the result to vector formats such as MVG or SVG.</p>
6287
6288<div style="margin: auto;">
6289<h3 class="magick-header"><a id="repage"></a>-repage <var>geometry</var></h3>
6290</div>
6291
6292<p class="magick-description">Adjust the canvas and offset information of the image.</p>
6293
6294<p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
6295rather than a setting. You can separately set the canvas size or the offset
6296of the image on that canvas by only providing those components. </p>
6297
6298<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6299
6300<p>If a <code>!</code> flag is given the offset given is added to the existing
6301offset to move the image relative to its previous position. This useful for
6302animation sequences. </p>
6303
6304<p>A given a canvas size of zero such as '<code>0x0</code>' forces it to
6305recalculate the canvas size so the image (at its current offset) will appear
6306completely on that canvas (unless it has a negative offset).</p>
6307
6308<p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
6309canvas meta-data from the images. </p>
6310
6311<p>The <a href="command-line-options.html#set">-set</a> '<code>page</code>' option can be used to
6312directly assign virtual canvas meta-data. </p>
6313
6314
6315<div style="margin: auto;">
6316 <h3 class="magick-header"><a id="resample"></a>-resample <var>horizontal</var>x<var>vertical</var></h3>
6317</div>
6318
6319<p class="magick-description">Resample image to specified horizontal and vertical resolution.</p>
6320
6321<p>Resize the image so that its rendered size remains the same as the original
6322at the specified target resolution. For example, if a 300 DPI image renders at
63233 inches by 2 inches on a 300 DPI device, when the image has been resampled to
632472 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that
6325only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
6326storing the image resolution. For formats which do not support an image
6327resolution, the original resolution of the image must be specified via <a href="command-line-options.html#density">-density</a> on the command line prior to specifying the
6328resample resolution.</p>
6329
6330<p>Note that Photoshop stores and obtains image resolution from a proprietary
6331embedded profile. If this profile exists in the image, then Photoshop will
6332continue to treat the image using its former resolution, ignoring the image
6333resolution specified in the standard file header.</p>
6334
6335<div style="margin: auto;">
6336 <h3 class="magick-header"><a id="resize"></a>-resize <var>geometry</var></h3>
6337</div>
6338
6339<p class="magick-description">Resize an image.</p>
6340
6341<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6342ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
6343
6344<p>If the <a href="command-line-options.html#filter">-filter</a> option
6345or <code>-define filter:option=value</code> precedes the <a href="command-line-options.html#resize">-resize</a> option, the image is resized with the specified
6346filter.</p>
6347
6348<p>Many image processing algorithms assume your image is in a linear-light
6349coding. If your image is gamma-corrected, you can remove the nonlinear gamma
6350correction, apply the transform, then restore it like this:</p>
6351
6352<pre>
6353convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \
6354 -quality 92 passport.jpg
6355</pre>
6356
6357<div style="margin: auto;">
6358 <h3 class="magick-header"><a id="respect-parentheses"></a>-respect-parentheses</h3>
6359</div>
6360
6361<p class="magick-description">settings remain in effect until parenthesis boundary.</p>
6362
6363<div style="margin: auto;">
6364 <h3 class="magick-header"><a id="reverse"></a>-reverse</h3>
6365</div>
6366
6367<p class="magick-description">Reverse the order of images in the current image list.</p>
6368
6369
6370<div style="margin: auto;">
6371 <h3 class="magick-header"><a id="roll"></a>-roll {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
6372</div>
6373
6374<p class="magick-description">roll an image vertically or horizontally by the amount given.</p>
6375
6376<p>A negative <var>x</var> offset rolls the image right-to-left.
6377A negative <var>y</var> offset rolls the image bottom-to-top.</p>
6378
6379
6380<div style="margin: auto;">
6381 <h3 class="magick-header"><a id="rotate"></a>-rotate <var>degrees</var>{<var>&lt;</var>}{<var>&gt;</var>}</h3>
6382</div>
6383
6384<p class="magick-description">Apply Paeth image rotation (using shear operations) to the image.</p>
6385
6386<p>Use <code>&gt;</code> to rotate the image only if its width exceeds the
6387height. <code>&lt;</code> rotates the image <var>only</var> if its width is less
6388than the height. For example, if you specify <code>-rotate "-90&gt;"</code> and
6389the image size is 480x640, the image is not rotated. However, if the image is
6390640x480, it is rotated by -90 degrees. If you use <code>&gt;</code> or
6391<code>&lt;</code>, enclose it in quotation marks to prevent it from being
6392misinterpreted as a file redirection.</p>
6393
6394<p>Empty triangles in the corners, left over from rotating the image, are
6395filled with the <code>background</code> color. </p>
6396
6397<p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
6398'<code>ScaleRotateTranslate</code>' distort method. </p>
6399
6400
6401<div style="margin: auto;">
6402 <h3 class="magick-header"><a id="sample"></a>-sample <var>geometry</var></h3>
6403</div>
6404
6405<p class="magick-description">minify / magnify the image with pixel subsampling and pixel replication, respectively.</p>
6406
6407<p>Change the image size simply by directly sampling the pixels original
6408from the image. When magnifying, pixels are replicated in blocks. When
6409minifying, pixels are sub-sampled (i.e., some rows and columns are skipped
6410over). </p>
6411
6412<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6413a <a href="command-line-options.html#filter">-filter</a> setting of <code>point</code> (nearest
6414neighbour), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
6415avoids all the filter processing of the image. As such it completely ignores
6416the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6417
6418<p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
6419will be added to the resulting image, though some colors may disappear. </p>
6420
6421<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Offsets, if present in the geometry string, are
6422ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
6423
6424
6425<p>The actual sampling point is the middle of the sub-region being sampled.
6426As such a single pixel sampling of an image will take the middle pixel, (or
6427top-left-middle if image has even dimensions). However the <a href="command-line-options.html#define">-define</a> '<code>sample:offset</code>' can be set to modify
6428this position some other location within each sub-region being sampled, as
6429a percentage offset.</p>
6430
6431<p>By default this value is '<code>50</code>' for the midpoint, but could be set
6432to '<code>0</code>' for top-left, '<code>100</code>' for bottom-right, or with
6433separate X and Y offsets such as '<code>0x50</code>' for left-middle edge of
6434sampling sub-region.</p>
6435
6436
6437<div style="margin: auto;">
6438 <h3 class="magick-header"><a id="sampling-factor"></a>-sampling-factor <var>horizontal-factor</var>x<var>vertical-factor</var></h3>
6439</div>
6440
6441<p class="magick-description">sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</p>
6442
6443<p>This option specifies the sampling factors to be used by the JPEG encoder
6444for chroma downsampling. If this option is omitted, the JPEG library will use
6445its own default values. When reading or writing the YUV format and when
6446writing the M2V (MPEG-2) format, use <a href="command-line-options.html#sampling-factor">-sampling-factor 2x1</a> or <a href="command-line-options.html#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2
6447downsampling method.</p>
6448
6449<div style="margin: auto;">
6450 <h3 class="magick-header"><a id="scale"></a>-scale <var>geometry</var></h3>
6451</div>
6452
6453<p class="magick-description">minify / magnify the image with pixel block averaging and pixel replication, respectively.</p>
6454
6455<p>Change the image size simply by replacing pixels by averaging pixels
6456together when minifying, or replacing pixels when magnifying. </p>
6457
6458<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6459a <a href="command-line-options.html#filter">-filter</a> setting of <code>box</code>. Though it is a lot
6460faster, as it avoids all the filter processing of the image. As such it
6461completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6462
6463<p>If when shrinking (minifying) images the original image is some integer
6464multiple of the new image size, the number of pixels averaged together to
6465produce the new pixel color is the same across the whole image. This is
6466a special case known as 'binning' and is often used as a method of reducing
6467noise in image such as those generated by digital cameras, especially in low
6468light conditions. </p>
6469
6470
6471<div style="margin: auto;">
6472 <h3 class="magick-header"><a id="scene"></a>-scene <var>value</var></h3>
6473</div>
6474
6475<p class="magick-description">set scene number.</p>
6476
6477<p>This option sets the scene number of an image or the first image in an image sequence.</p>
6478
6479<div style="margin: auto;">
6480 <h3 class="magick-header"><a id="screen"></a>-screen</h3>
6481</div>
6482
6483<p class="magick-description">specify the screen to capture.</p>
6484
6485<p>This option indicates that the GetImage request used to obtain the image
6486should be done on the root window, rather than directly on the specified
6487window. In this way, you can obtain pieces of other windows that overlap the
6488specified window, and more importantly, you can capture menus or other popups
6489that are independent windows but appear over the specified window.</p>
6490
6491<div style="margin: auto;">
6492 <h3 class="magick-header"><a id="seed"></a>-seed</h3>
6493</div>
6494
6495<p class="magick-description">seed a new sequence of pseudo-random numbers</p>
6496
6497<div style="margin: auto;">
6498 <h3 class="magick-header"><a id="segment"></a>-segment <var>cluster-threshold</var>x<var>smoothing-threshold</var></h3>
6499</div>
6500
6501<p class="magick-description">segment the colors of an image.</p>
6502
6503<p>Segment an image by analyzing the histograms of the color components and
6504identifying units that are homogeneous with the fuzzy c-means technique. This
6505is part of the ImageMagick color quantization routines. </p>
6506
6507<p>Specify <var>cluster threshold</var> as the number of pixels in
6508each cluster that must exceed the cluster threshold to be considered valid.
6509<var>Smoothing threshold</var> eliminates noise in the second
6510derivative of the histogram. As the value is increased, you can expect
6511a smoother second derivative. The default is 1.5.</p>
6512
6513<p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6514of the color clusters is returned.</p>
6515
6516
6517<div style="margin: auto;">
6518 <h3 class="magick-header"><a id="selective-blur"></a>-selective-blur <var>radius</var><br>-selective-blur <var>radius</var>x<var>sigma</var>{<var>+threshold</var>}</h3>
6519</div>
6520
6521<p class="magick-description">Selectively blur pixels within a contrast threshold.</p>
6522
6523<p>Blurs those pixels that are less than or equal to the threshold in
6524contrast. The threshold may be expressed as a fraction of <var>QuantumRange</var> or as a percentage.</p>
6525
6526<div style="margin: auto;">
6527 <h3 class="magick-header"><a id="separate"></a>-separate</h3>
6528</div>
6529
6530<p class="magick-description">separate an image channel into a grayscale image. Specify the channel with <a href="command-line-options.html#channel">-channel</a>.</p>
6531
6532<div style="margin: auto;">
6533 <h3 class="magick-header"><a id="sepia-tone"></a>-sepia-tone <var>threshold</var></h3>
6534</div>
6535
6536<p class="magick-description">simulate a sepia-toned photo.</p>
6537
6538<p>Specify <var>threshold</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6539
6540<p>This option applies a special effect to the image, similar to the effect
6541achieved in a photo darkroom by sepia toning. Threshold ranges from 0 to <var>QuantumRange</var> and is a measure of the extent of the sepia
6542toning. A threshold of 80% is a good starting point for a reasonable
6543tone.</p>
6544
6545
6546
6547<div style="margin: auto;">
6548 <h3 class="magick-header"><a id="set"></a>-set <var>key value</var></h3>
6549 <h3 class="magick-header">+set <var>key</var></h3>
6550</div>
6551
6552<p class="magick-description">sets image attributes and properties for images in the current image sequence.</p>
6553
6554<p>This will assign (or modify) specific settings attached to all the images
6555in the current image sequence. Using the <a href="command-line-options.html#set">+set</a> form of the
6556option will either remove, or reset that setting to a default state, as
6557appropriate. </p>
6558
6559<p>For example, it will modify specific well known image meta-data
6560'attributes' such as those normally overridden by: the options <a href="command-line-options.html#delay">-delay</a>, <a href="command-line-options.html#dispose">-dispose</a>, and <a href="command-line-options.html#page">-page</a>, <a href="command-line-options.html#colorspace">-colorspace</a>; generally
6561assigned before the image is read in, by using a <var>key</var> of
6562the same name. </p>
6563
6564<p>If the given <var>key</var> does not match a specific known
6565'attribute ', such as shown above, the setting is stored as a a free form
6566'property' string. Such settings are listed in <a href="command-line-options.html#verbose">-verbose</a> information ("<code>info:</code>" output format) as "Properties".
6567</p>
6568
6569<p>This includes string 'properties' that are set by and assigned to images
6570using the options <a href="command-line-options.html#comment">-comment</a>, <a href="command-line-options.html#label">-label</a>, <a href="command-line-options.html#caption">-caption</a>. These options actually assign
6571a global 'artifact' which are automatically assigned (and any <a href="escape.html">Format Percent
6572Escapes</a> expanded) to images as they are read in. For example:</p>
6573
6574<pre>
6575-&gt; convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png
6576identify -format %c rose.png
6577Rose is a rose is a rose is a rose
6578</pre>
6579
6580<p>The set value can also make use of <a href="escape.html">Format and Print Image
6581Properties</a> in the defined value. For example:</p>
6582
6583<pre>
6584-&gt; convert rose: -set origsize '%wx%h' -resize 50% \
6585 -format 'Old size = %[origsize] New size = %wx%h' info:
6586Old size = 70x46 New size = 35x23
6587</pre>
6588
Cristy4de4f202015-09-16 16:50:53 -0400[diff] [blame]6589<p>Other well known 'properties' that are available include:
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]6590'<code>date:create</code>' and '<code>date:modify</code>' and
6591'<code>signature</code>'. </p>
6592
6593<p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6594the '<code>page</code>' attribute of an image for images already in memory (also
6595see <a href="command-line-options.html#repage">-page</a>). However it is designed to provide a finer
6596control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6597option will only provide a direct, unmodified assignment of '<code>page</code>'
6598attribute. </p>
6599
6600<p>This option can also associate a colorspace or profile with your image.
6601For example,</p>
6602
6603<pre>
6604convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd
6605</pre>
6606
6607<p>Some 'properties' must be defined in a specific way to be used. For
6608example only 'properties' prefixed with "<code>filename:</code>" can be used to
6609modify the output filename of an image. For example</p>
6610
6611<pre>
6612convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'
6613</pre>
6614
6615<p>If the setting value is prefixed with "<code>option:</code>" the setting will
6616be saved as a global "Artifact" exactly as if it was set using the <a href="command-line-options.html#define">-define</a> option. As such settings are global in scope, they
6617can be used to pass 'attributes' and 'properties' of one specific image,
6618in a way that allows you to use them in a completely different image, even if
6619the original image has long since been modified or destroyed. For example: </p>
6620
6621<pre>
6622convert rose: -set option:rosesize '%wx%h' -delete 0 \
6623 label:'%[rosesize]' label_size_of_rose.gif"
6624</pre>
6625
6626<p>Note that <a href="escape.html">Format Percent Escapes</a> will only match
6627a 'artifact' if the given <var>key</var> does not match an existing
6628'attribute' or 'property'. </p>
6629
6630<p>You can set the attributes of the image registry by prefixing the value
6631with <code>registry:</code>.</p>
6632
6633<p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
6634previously-formatted ancillary chunks into the output PNG file, using
6635the commandline option as shown below or by setting the profile via a
6636programming interface:</p>
6637
6638<pre>
6639convert in.png -set profile PNG-chunk-x:&lt;filename&gt; out.png
6640</pre>
6641
6642<p>where <var>x</var> is a location flag and
6643<var>filename</var> is a file containing the chunk
6644name in the first 4 bytes, then a colon (":"), followed by the chunk data.
6645This encoder will compute the chunk length and CRC, so those must not
6646be included in the file.</p>
6647
6648<p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
6649or "e" (end, i.e., after IDAT). If you want to write multiple chunks
6650of the same type, then add a short unique string after the "x" to prevent
6651subsequent profiles from overwriting the preceding ones, e.g.,</p>
6652
6653
6654<pre>
6655convert in.png -set profile PNG-chunk-b01:file01 \
6656 -profile PNG-chunk-b02:file02 out.png
6657</pre>
6658
6659<div style="margin: auto;">
6660 <h3 class="magick-header"><a id="shade"></a>-shade <var>azimuth</var>x<var>elevation</var></h3>
6661</div>
6662
6663<p class="magick-description">shade the image using a distant light source.</p>
6664
6665<p>Specify <var>azimuth</var> and <var>elevation</var> as
6666the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
6667the shading results as a grayscale image.</p>
6668
6669<div style="margin: auto;">
6670 <h3 class="magick-header"><a id="shadow"></a>-shadow <var>percent-opacity</var>{x<var>sigma</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var>{<var>%</var>}</h3>
6671</div>
6672
6673<p class="magick-description">simulate an image shadow.</p>
6674
6675<div style="margin: auto;">
6676 <h3 class="magick-header"><a id="shared-memory"></a>-shared-memory</h3>
6677</div>
6678
6679<p class="magick-description">use shared memory.</p>
6680
6681<p>This option specifies whether the utility should attempt to use shared
6682memory for pixmaps. ImageMagick must be compiled with shared memory support,
6683and the display must support the <var>MIT-SHM</var> extension.
6684Otherwise, this option is ignored. The default is <code>True</code>.</p>
6685
6686<div style="margin: auto;">
6687 <h3 class="magick-header"><a id="sharpen"></a>-sharpen <var>radius</var><br>-sharpen <var>radius</var>x<var>sigma</var></h3>
6688</div>
6689
6690<p class="magick-description">sharpen the image.</p>
6691
6692<p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
6693
6694<div style="margin: auto;">
6695 <h3 class="magick-header"><a id="shave"></a>-shave <var>geometry</var></h3>
6696</div>
6697
6698<p class="magick-description">Shave pixels from the image edges.</p>
6699
6700<p>The <var>size</var> portion of the <var>geometry</var>
6701argument specifies the width of the region to be removed from both sides of
6702the image and the height of the regions to be removed from top and bottom.
6703Offsets are ignored.</p>
6704
6705<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6706
6707<div style="margin: auto;">
6708 <h3 class="magick-header"><a id="shear"></a>-shear <var>Xdegrees</var>[x<var>Ydegrees</var>]</h3>
6709</div>
6710
6711<p class="magick-description">Shear the image along the x-axis and/or y-axis.</p>
6712
6713<p>The shear angles may be positive, negative, or zero. When <var>Ydegrees</var> is omitted it defaults to 0. When both angles are
6714given, the horizontal component of the shear is performed before the vertical
6715component.</p>
6716
6717<p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
6718horizontally or vertically, respectively),creating a parallelogram. The amount
6719of each is controlled by the respective shear angle. For horizontal shears,
6720<var>Xdegrees</var> is measured clockwise relative to "up" (the
6721negative y-axis), sliding the top edge to the right when 0°&lt;<var>Xdegrees</var>&lt;90° and to the left when 90°&lt;<var>Xdegrees</var>&lt;180°. For vertical shears <var>Ydegrees</var> is measured clockwise relative to "right" (the
6722positive x-axis), sliding the right edge down when 0°&lt;<var>Ydegrees</var>&lt;90° and up when 90°&lt;<var>Ydegrees</var>&lt;180°.</p>
6723
6724<p>Empty triangles left over from shearing the image are filled with the color
6725defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
6726using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6727
6728<p>The horizontal shear is performed before the vertical part. This is
6729important to note, since horizontal and vertical shears do not
6730<var>commute</var>, i.e., the order matters in a sequence of shears. For
6731example, the following two commands are not equivalent.</p>
6732
6733<pre>
6734convert logo: -shear 20x0 -shear 0x60 logo-sheared.png
6735convert logo: -shear 0x60 -shear 20x0 logo-sheared.png
6736</pre>
6737
6738<p>The first of the two commands above is equivalent to the following, except
6739for the amount of empty space created; the command that follows generates
6740a smaller image, and so is a better choice in terms of time and space.</p>
6741
6742<pre>
6743convert logo: -shear 20x60 logo-sheared.png
6744</pre>
6745
6746<div style="margin: auto;">
6747 <h3 class="magick-header"><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <var>contrast</var>x<var>mid-point</var></h3>
6748</div>
6749
6750<p class="magick-description">increase the contrast without saturating highlights or shadows.</p>
6751
6752<p>Increase the contrast of the image using a sigmoidal transfer function
6753without saturating highlights or shadows. <var>Contrast</var>
6754indicates how much to increase the contrast. For example, 0 is none, 3 is
6755typical and 20 is a lot.
6756</p>
6757
6758<p>The <var>mid-point</var> indicates where the maximum change
6759'slope' in contrast should fall in the resultant image (0 is white; 50% is
6760middle-gray; 100% is black). </p>
6761
6762<p>By default the image contrast is increased, use <var>+sigmoidal-contrast</var> to decrease the contrast.</p>
6763
6764<p>To achieve the equivalent of a sigmoidal brightness change (similar to
6765a gamma adjustment), you would use <var>-sigmoidal-contrast
6766{brightness}x0%</var> to increase brightness and <var>+sigmoidal-contrast {brightness}x0%</var> to decrease brightness.
6767Note the use of '0' fo rthe mid-point of the sigmoidal curve. </p>
6768
6769<p>Using a very high <var>contrast</var> will produce a sort of
6770'smoothed thresholding' of the image. Not as sharp (with high aliasing
6771effects) of a true threshold, but with tapered gray-levels around the threshold
6772<var>mid-point</var>. </p>
6773
6774<div style="margin: auto;">
6775 <h3 class="magick-header"><a id="silent"></a>-silent</h3>
6776</div>
6777
6778<p class="magick-description">operate silently.</p>
6779
6780<div style="margin: auto;">
6781 <h3 class="magick-header"><a id="similarity-threshold"></a>-similarity-threshold <var>value</var></h3>
6782</div>
6783
6784<p class="magick-description">minimum RMSE for subimage match.</p>
6785
6786<p>If this setting is used, then the search will stop as soon as it finds a match whose metric is less than or equal to the value. A partially filled second output image will result. Using a value of zero, will cause the search to stop at the first perfect match it finds. If this setting is left off, then the search will proceed to completion or as limited by <var>-dissimilarity-threshold</var>.</p>
6787
6788<div style="margin: auto;">
6789 <h3 class="magick-header"><a id="size"></a>-size <var>width</var>[x<var>height</var>][<var>+offset</var>]</h3>
6790</div>
6791
6792<p class="magick-description">set the width and height of the image.</p>
6793
6794<p>Use this option to specify the width and height of raw images whose
6795dimensions are unknown such as <code>GRAY</code>, <code>RGB</code>, or
6796<code>CMYK</code>. In addition to width and height, use <a href="command-line-options.html#size">-size</a> with an offset to skip any header information in the
6797image or tell the number of colors in a <code>MAP</code> image file, (e.g. -size
6798640x512+256).</p>
6799
6800<p>For Photo CD images, choose from these sizes:</p>
6801
6802<pre>
6803192x128
6804384x256
6805768x512
68061536x1024
68073072x2048
6808</pre>
6809
6810<div style="margin: auto;">
6811 <h3 class="magick-header"><a id="sketch"></a>-sketch <var>radius</var><br>-sketch <var>radius</var>x<var>sigma</var>+<var>angle</var></h3>
6812</div>
6813
6814<p class="magick-description">simulate a pencil sketch.</p>
6815
6816<p>Sketch with the given radius, standard deviation (sigma), and angle. The
6817angle given is the angle toward which the image is sketched. That is the
6818direction people would consider the object is coming from. </p>
6819
6820<div style="margin: auto;">
6821 <h3 class="magick-header"><a id="smush"></a>-smush <var>offset</var></h3>
6822</div>
6823
6824<p class="magick-description">smush an image sequence together.</p>
6825
6826<div style="margin: auto;">
6827 <h3 class="magick-header"><a id="snaps"></a>-snaps <var>value</var></h3>
6828</div>
6829
6830<p class="magick-description">Set the number of screen snapshots.</p>
6831
6832<p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
6833
6834<div style="margin: auto;">
6835 <h3 class="magick-header"><a id="solarize"></a>-solarize <var>threshold</var></h3>
6836</div>
6837
6838<p class="magick-description">negate all pixels above the threshold level.</p>
6839
6840<p>Specify <var>factor</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6841
6842<p>This option produces a <var>solarization</var> effect seen when
6843exposing a photographic film to light during the development process.</p>
6844
6845<div style="margin: auto;">
6846 <h3 class="magick-header"><a id="sparse-color"></a>-sparse-color <var>method</var> '<var>x</var>,<var>y</var> <var>color</var> ...'</h3>
6847</div>
6848
6849<p class="magick-description"> color the given image using the specified points of color, and filling the other intervening colors using the given methods. </p>
6850
6851
6852<dl class="dl-horizontal">
6853 <dt>barycentric</dt>
6854 <dd>three point triangle of color given 3 points.
6855 Giving only 2 points will form a linear gradient between those points.
6856 The gradient generated extends beyond the triangle created by those
6857 3 points. </dd>
6858 <dt>bilinear</dt>
6859 <dd>Like barycentric but for 4 points. Less than 4 points
6860 fall back to barycentric. </dd>
6861 <dt>voronoi</dt>
6862 <dd>Simply map each pixel to the to nearest color point
6863 given. The result are polygonal 'cells' of solid color. </dd>
Eric McConville04bb72a2015-09-24 13:33:45 -0500[diff] [blame]6864 <dt>manhatten</dt>
6865 <dd>Like voronoi, but resulting polygonal 'cells' are mapped
6866 to fixed coordinate system.</dd>
Cristyb57c2352015-08-25 20:01:06 -0400[diff] [blame]6867 <dt>shepards</dt>
6868 <dd>Colors points biased on the ratio of inverse distance
6869 squared. Generating spots of color in a sea of the average of
6870 colors. </dd>
6871 <dt>inverse</dt>
6872 <dd>Colors points biased on the ratio of inverse distance.
6873 This generates sharper points of color rather than rounded spots of
6874 '<code>shepards</code>' Generating spots of color in a sea of the
6875 average of colors. </dd>
6876</dl>
6877
6878<p>The points are placed according to the images location on the virtual
6879canvas (<a href="command-line-options.html#page">-page</a> or <a href="command-line-options.html#repage">-repage</a>
6880offset), and do not actually have to exist on the given image, but may be
6881some point beyond the edge of the image. All points are floating point values.
6882</p>
6883
6884<p>Only the color channels defined by the <a href="command-line-options.html#channel">-channel</a> are
6885modified, which means that by default matte/alpha transparency channel is not
6886effected. Typically transparency channel is turned off either before or after
6887the operation. </p>
6888
6889<p>Of course if some color points are transparent to generate a transparent
6890gradient, then the image also requires transparency enabled to store the
6891values. </p>
6892
6893<p>All the above methods when given a single point of color will replace all
6894the colors in the image with the color given, regardless of the point. This is
6895logical, and provides an alternative technique to recolor an image to some
6896default value. </p>
6897
6898
6899<div style="margin: auto;">
6900 <h3 class="magick-header"><a id="splice"></a>-splice <var>geometry</var></h3>
6901</div>
6902
6903<p class="magick-description">Splice the current background color into the image.</p>
6904
6905<p>This will add rows and columns of the current <a href="command-line-options.html#background">-background</a> color into the given image according to the
6906given <a href="command-line-options.html#gravity">-gravity</a> geometry setting. See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. Essentially <a href="command-line-options.html#splice">-splice</a> will divide the
6907image into four quadrants, separating them by the inserted rows and columns.
6908</p>
6909
6910<p>If a dimension of geometry is zero no rows or columns will be added for that
6911dimension. Similarly using a zero offset with the appropriate <a href="command-line-options.html#gravity">-gravity</a> setting will add rows and columns to the edges of
6912the image, padding the image only along that one edge. Edge padding is what <a href="command-line-options.html#splice">-splice</a> is most commonly used for. </p>
6913
6914<p>If the exact same <var>geometry</var> and <a href="command-line-options.html#gravity">-gravity</a> is later used with <a href="command-line-options.html#chop">-chop</a> the
6915added added all splices removed. </p>
6916
6917<div style="margin: auto;">
6918 <h3 class="magick-header"><a id="spread"></a>-spread <var>amount</var></h3>
6919</div>
6920
6921<p class="magick-description">displace image pixels by a random amount.</p>
6922
6923<p>The argument <var>amount</var> defines the size of the
6924neighborhood around each pixel from which to choose a candidate pixel to
6925blend.</p>
6926
6927<p>The lookup is controlled by the <a href="command-line-options.html#interpolate">-interpolate</a> setting.</p>
6928
6929<div style="margin: auto;">
6930 <h3 class="magick-header"><a id="statistic"></a>-statistic <var>type</var> <var>geometry</var></h3>
6931</div>
6932
6933<p class="magick-description">replace each pixel with corresponding statistic from the neighborhood.</p>
6934
6935<p>Choose from these statistic types:</p>
6936<dl class="dl-horizontal">
6937<dt>Gradient</dt><dd>maximum difference (max - min) value in neighborhood</dd>
6938<dt>Maximum</dt><dd>maximum value per channel in neighborhood</dd>
6939<dt>Minimum</dt><dd>minimum value per channel in neighborhood</dd>
6940<dt>Mean</dt><dd>average value per channel in neighborhood</dd>
6941<dt>Median</dt><dd>median value per channel in neighborhood</dd>
6942<dt>Mode</dt><dd>mode (most frequent) value per channel in neighborhood</dd>
6943<dt>Nonpeak</dt><dd>value just before or after the median value per channel in neighborhood</dd>
6944<dt>RMS</dt><dd>root mean square value per channel in neighborhood</dd>
6945<dt>StandardDeviation</dt><dd> standard deviation value per channel in neighborhood</dd>
6946</dl>
6947
6948<div style="margin: auto;">
6949 <h3 class="magick-header"><a id="stegano"></a>-stegano <var>offset</var></h3>
6950</div>
6951
6952<p class="magick-description">hide watermark within an image.</p>
6953
6954<p>Use an offset to start the image hiding some number of pixels from the
6955beginning of the image. Note this offset and the image size. You will need
6956this information to recover the steganographic image (e.g. display -size
6957320x256+35 stegano:image.png).</p>
6958
6959<div style="margin: auto;">
6960 <h3 class="magick-header"><a id="stereo"></a>-stereo <var>+x</var>{<var>+y</var>}</h3>
6961</div>
6962
6963<p class="magick-description">composite two images to create a red / cyan stereo anaglyph.</p>
6964
6965<p>The left side of the stereo pair (second image) is saved as the red channel of the output image. The right side (first image) is saved as the green and blue channels. Red-green stereo glasses are required to properly view the stereo image.</p>
6966
6967<div style="margin: auto;">
6968 <h3 class="magick-header"><a id="storage-type"></a>-storage-type <var>type</var></h3>
6969</div>
6970
6971<p class="magick-description">pixel storage type. Here are the valid types:</p>
6972
6973<dl class="dl-horizontal">
6974<dt>char</dt><dd>unsigned characters</dd>
6975<dt>double</dt><dd>doubles</dd>
6976<dt>float</dt><dd>floats</dd>
6977<dt>integer</dt><dd>integers</dd>
6978<dt>long</dt><dd>longs</dd>
6979<dt>quantum</dt><dd>pixels in the native depth of your ImageMagick distribution</dd>
6980<dt>short</dt><dd>unsigned shorts</dd>
6981</dl>
6982
6983<p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
6984values range from 0 to the maximum value the storage type can support.</p>
6985
6986<div style="margin: auto;">
6987 <h3 class="magick-header"><a id="stretch"></a>-stretch <var>fontStretch</var></h3>
6988</div>
6989
6990<p class="magick-description">Set a type of stretch style for fonts.</p>
6991
6992<p>This setting suggests a type of stretch that ImageMagick should try to
6993apply to the currently selected font family. Select <var>fontStretch</var> from the following.</p>
6994
6995<pre>
6996Any
6997Condensed
6998Expanded
6999ExtraCondensed
7000ExtraExpanded
7001Normal
7002SemiCondensed
7003SemiExpanded
7004UltraCondensed
7005UltraExpanded
7006</pre>
7007
7008<p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
7009stretch</a>.</p>
7010
7011<p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
7012
7013<div style="margin: auto;">
7014 <h3 class="magick-header"><a id="strip"></a>-strip</h3>
7015</div>
7016
7017<p class="magick-description">strip the image of any profiles or comments.</p>
7018
7019<div style="margin: auto;">
7020 <h3 class="magick-header"><a id="stroke"></a>-stroke <var>color</var></h3>
7021</div>
7022
7023<p class="magick-description">color to use when stroking a graphic primitive.</p>
7024
7025<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7026
7027<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7028
7029<div style="margin: auto;">
7030 <h3 class="magick-header"><a id="strokewidth"></a>-strokewidth <var>value</var></h3>
7031</div>
7032
7033<p class="magick-description">set the stroke width.</p>
7034
7035<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7036
7037<div style="margin: auto;">
7038 <h3 class="magick-header"><a id="style"></a>-style <var>fontStyle</var></h3>
7039</div>
7040
7041<p class="magick-description">Set a font style for text.</p>
7042
7043<p>This setting suggests a font style that ImageMagick should try to apply to
7044the currently selected font family. Select <var>fontStyle</var> from
7045the following.</p>
7046
7047<pre>
7048Any
7049Italic
7050Normal
7051Oblique
7052</pre>
7053
7054<p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
7055
7056<div style="margin: auto;">
7057 <h3 class="magick-header"><a id="subimage-search"></a>-subimage-search</h3>
7058</div>
7059
7060<p class="magick-description">search for subimage.</p>
7061
7062<p>This option is required to have compare search for the best match location
7063of a small image within a larger image. This search will produce two images
7064(or two frames). The first is the "difference" image and the second will
7065be the "match score" image.</p>
7066
7067<p>The "match-score" image is smaller containing a pixel for ever possible
7068position of the top-left corner of the given sub-image. that is its size will
7069be the size of the larger_image - sub_image + 1. The brightest location in
7070this image is the location s the locate on the best match that is also
7071reported. Note that this may or may not be a perfect match, and the actual
7072brightness will reflect this. Other bright 'peaks' can be used to locate other
7073possible matching locations. </p>
7074
7075<p>Note that the search will try to compare the sub-image at every possible
7076location in the larger image, as such it can be very slow. The smaller the
7077sub-image the faster this search is. </p>
7078
7079
7080<div style="margin: auto;">
7081 <h3 class="magick-header"><a id="swap"></a>-swap <var>index,index</var></h3>
7082</div>
7083
7084<p class="magick-description">Swap the positions of two images in the image sequence.</p>
7085
7086<p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
7087images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
7088the last two images in the sequence.</p>
7089
7090<div style="margin: auto;">
7091 <h3 class="magick-header"><a id="swirl"></a>-swirl <var>degrees</var></h3>
7092</div>
7093
7094<p class="magick-description">swirl image pixels about the center.</p>
7095
7096<p><var>Degrees</var> defines the tightness of the swirl.</p>
7097
7098<div style="margin: auto;">
7099 <h3 class="magick-header"><a id="synchronize"></a>-synchronize</h3>
7100</div>
7101
7102<p class="magick-description">synchronize image to storage device.</p>
7103
7104<p>Set to "true" to ensure all image data is fully flushed and synchronized
7105to disk. There is a performance penalty, but the benefits include ensuring a
7106valid image file in the event of a system crash and early reporting if there
7107is not enough disk space for the image pixel cache.</p>
7108
7109<div style="margin: auto;">
7110 <h3 class="magick-header"><a id="taint"></a>-taint</h3>
7111</div>
7112
7113<p class="magick-description">Mark the image as modified.</p>
7114
7115<div style="margin: auto;">
7116 <h3 class="magick-header"><a id="text-font"></a>-text-font <var>name</var></h3>
7117</div>
7118
7119<p class="magick-description">font for writing fixed-width text.</p>
7120
7121<p>Specifies the name of the preferred font to use in fixed (typewriter style)
7122formatted text. The default is 14 point <var>Courier</var>.</p>
7123
7124<p>You can tag a font to specify whether it is a PostScript, TrueType, or
7125OPTION1 font. For example, <code>Courier.ttf</code> is a TrueType font and
7126<code>x:fixed</code> is OPTION1.</p>
7127
7128<div style="margin: auto;">
7129 <h3 class="magick-header"><a id="texture"></a>-texture <var>filename</var></h3>
7130</div>
7131
7132<p class="magick-description">name of texture to tile onto the image background.</p>
7133
7134<div style="margin: auto;">
7135 <h3 class="magick-header"><a id="threshold"></a>-threshold <var>value</var>{<var>%</var>}</h3>
7136</div>
7137
7138<!-- {<var>green,blue,opacity</var>}
7139<p>If the green or blue value is omitted, these channels use the same value as
7140the first one provided. If all three color values are the same, the result is
7141a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
7142and any partially transparent pixel becomes fully transparent.</p>
7143-->
7144
7145<p class="magick-description">Apply simultaneous black/white threshold to the image.</p>
7146
7147<p>Any pixel values (more specifically, those channels set using <a href="command-line-options.html#channel">‑channel</a>) that exceed the specified threshold are reassigned the
7148maximum channel value, while all other values are assigned the minimum.</p>
7149
7150<p> The threshold value can be given as a percentage or as an absolute integer
7151value corresponding to the desired channel value. When given as an integer,
7152the minimum attainable value is 0 (corresponding to black when all channels
7153are affected), but the maximum value (corresponding to white) is that of the
7154<code>quantum depth</code> of the particular build of ImageMagick, and is
7155therefore dependent on the installation. For that reason, a reasonable
7156recommendation for most applications is to specify the threshold values as
7157a percentage. </p>
7158
7159<p> The following would force pixels with red values above 50% to have 100%
7160red values, while those at or below 50% red would be set to 0 in the red
7161channel. The green, blue, and alpha channels (if present) would be unchanged.
7162</p>
7163
7164<pre>
7165convert in.png -channel red -threshold 50% out.png
7166</pre>
7167
7168<p>As (possibly) impractical but instructive examples, the following would
7169generate an all-black and an all-white image with the same dimensions as the
7170input image.</p>
7171
7172
7173<pre>
7174convert in.png -threshold 100% black.png
7175convert in.png -threshold -1 white.png
7176</pre>
7177
7178<p>Note that the values of the transparency channel is treated as 'matte'
7179values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
7180
7181<p> See also <a href="command-line-options.html#black-threshold">‑black‑threshold</a> and <a href="command-line-options.html#white-threshold">‑white‑threshold</a>.
7182</p>
7183
7184<div style="margin: auto;">
7185 <h3 class="magick-header"><a id="thumbnail"></a>-thumbnail <var>geometry</var></h3>
7186</div>
7187
7188<p class="magick-description">Create a thumbnail of the image.</p>
7189
7190<p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
7191for speed and any image profile, other than a color profile, is removed to
7192reduce the thumbnail size. To strip the color profiles as well, add <a href="command-line-options.html#strip">-strip</a> just before of after this option.</p>
7193
7194<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7195
7196<div style="margin: auto;">
7197 <h3 class="magick-header"><a id="tile"></a>-tile <var>filename</var></h3>
7198</div>
7199
7200<p class="magick-description">Set the tile image used for filling a subsequent graphic primitive.</p>
7201
7202<div style="margin: auto;">
7203 <h3 class="magick-header">-tile <var>geometry</var></h3>
7204</div>
7205
7206<p class="magick-description">Specify the layout of images.</p>
7207
7208<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7209
7210<div style="margin: auto;">
7211 <h3 class="magick-header">-tile</h3>
7212</div>
7213
7214<p class="magick-description">Specifies that a subsequent composite operation is repeated across and down image.</p>
7215
7216<div style="margin: auto;">
7217 <h3 class="magick-header"><a id="tile-offset"></a>-tile-offset {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
7218</div>
7219
7220<p class="magick-description">Specify the offset for tile images, relative to the background image it is tiled on.</p>
7221
7222<p>This should be set before the tiling image is set by <a href="command-line-options.html#tile">-tile</a> or <a href="command-line-options.html#texture">-texture</a>, or directly applied for
7223creating a tiled canvas using <code>TILE:</code> or <code>PATTERN:</code> input
7224formats. </p>
7225
7226<p>Internally ImageMagick does a <a href="command-line-options.html#roll">-roll</a> of the tile image
7227by the arguments given when the tile image is set. </p>
7228
7229<div style="margin: auto;">
7230 <h3 class="magick-header"><a id="tint"></a>-tint <var>value</var></h3>
7231</div>
7232
7233<p class="magick-description">Tint the image with the fill color.</p>
7234
7235<p>Tint the image with the fill color.</p>
7236
7237<p>Specify the amount of tinting as a percentage. Pure colors like black,
7238white red, yellow, will not be affected by -tint. Only mid-range colors such
7239as the various shades of grey.</p>
7240
7241<div style="margin: auto;">
7242 <h3 class="magick-header"><a id="title"></a>-title <var>string</var></h3>
7243</div>
7244
7245<p class="magick-description">Assign a title to displayed image.", "animate", "display", "montage</p>
7246
7247<p>Use this option to assign a specific title to the image. This assigned to
7248the image window and is typically displayed in the window title bar.
7249Optionally you can include the image filename, type, width, height, Exif data,
7250or other image attribute by embedding special format characters described
7251under the <a href="command-line-options.html#format">-format</a> option.</p>
7252
7253<p>For example,</p>
7254
7255<pre>
7256-title "%m:%f %wx%h"
7257</pre>
7258
7259<p>produces an image title of <code>MIFF:bird.miff 512x480</code> for an image
7260titled <code>bird.miff</code> and whose width is 512 and height is 480.</p>
7261
7262
7263<div style="margin: auto;">
7264 <h3 class="magick-header"><a id="transform"></a>-transform</h3>
7265</div>
7266
7267<p class="magick-description">transform the image.</p>
7268
7269<p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
7270
7271<pre>
7272convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg
7273</pre>
7274
7275
7276<p>This operator has been now been superseded by the <a href="command-line-options.html#distort">-distort</a> '<code>AffineProjection</code>' method. </p>
7277
7278
7279<div style="margin: auto;">
7280 <h3 class="magick-header"><a id="transparent"></a>-transparent <var>color</var></h3>
7281</div>
7282
7283<p class="magick-description">Make this color transparent within the image.</p>
7284
7285<p>The <var>color</var> argument is defined using the format
7286described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz">-fuzz</a> setting can be used to match and replace colors similar to the one
7287given. </p>
7288
7289<p>Use <a href="command-line-options.html#transparent">+transparent</a> to invert the pixels matched.
7290that is make all non-matching colors transparent. </p>
7291
7292<p>The <a href="command-line-options.html#opaque">-opaque</a> operator is exactly the same as <a href="command-line-options.html#transparent">-transparent</a> but replaces the matching color with the
7293current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
7294However the <a href="command-line-options.html#transparent">-transparent</a> operator also ensures
7295that the image has an alpha channel enabled, as per "<code><a href="command-line-options.html#alpha">-alpha</a> set</code>", and does not require you to modify the <a href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
7296
7297<p>Note that this does not define the color as being the 'transparency color'
7298used for color-mapped image formats, such as GIF. For that use <a href="command-line-options.html#transparent-color">-transparent-color</a> </p>
7299
7300
7301<div style="margin: auto;">
7302 <h3 class="magick-header"><a id="transparent-color"></a>-transparent-color <var>color</var></h3>
7303</div>
7304
7305<p class="magick-description">Set the transparent color.</p>
7306
7307<p>Sometimes this is used for saving to image formats such as
7308GIF and PNG8 which uses this color to represent boolean transparency. This
7309does not make a color transparent, it only defines what color the transparent
7310color is in the color palette of the saved image. Use <a href="command-line-options.html#transparent">-transparent</a> to make an opaque color transparent.</p>
7311
7312<p>This option allows you to have both an opaque visible color, as well as a
7313transparent color of the same color value without conflict. That is, you can
7314use the same color for both the transparent and opaque color areas within an
7315image. This, in turn, frees to you to select a transparent color that is
7316appropriate when an image is displayed by an application that does not handle a
7317transparent color index, while allowing ImageMagick to correctly handle images of this
7318type. </p>
7319
7320<p>The default transparent color is <code>#00000000</code>, which is fully transparent black.</p>
7321
7322<div style="margin: auto;">
7323 <h3 class="magick-header"><a id="transpose"></a>-transpose</h3>
7324</div>
7325
7326<p class="magick-description">Mirror the image along the top-left to bottom-right diagonal.</p>
7327
7328<p> This option mathematically transposes the pixel array. It is equivalent to the sequence <code>-flip -rotate 90</code>.
7329</p>
7330
7331<div style="margin: auto;">
7332 <h3 class="magick-header"><a id="transverse"></a>-transverse</h3>
7333</div>
7334
7335<p class="magick-description">Mirror the image along the images bottom-left top-right diagonal. Equivalent to the operations <code>-flop -rotate 90</code>.</p>
7336
7337
7338<div style="margin: auto;">
7339 <h3 class="magick-header"><a id="treedepth"></a>-treedepth <var>value</var></h3>
7340</div>
7341
7342<p class="magick-description">tree depth for the color reduction algorithm.</p>
7343
7344<p>Normally, this integer value is zero or one. A value of zero or one causes
7345the use of an optimal tree depth for the color reduction algorithm.</p>
7346
7347<p>An optimal depth generally allows the best representation of the source
7348image with the fastest computational speed and the least amount of memory.
7349However, the default depth is inappropriate for some images. To assure the
7350best representation, try values between 2 and 8 for this parameter. Refer to
7351the <a href="quantize.html">color reduction algorithm</a> for more details.</p>
7352
7353<p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
7354option, or writing to an image format which requires color reduction, is
7355required for this option to take effect.</p>
7356
7357<div style="margin: auto;">
7358 <h3 class="magick-header"><a id="trim"></a>-trim</h3>
7359</div>
7360
7361<p class="magick-description">trim an image.</p>
7362
7363<p>This option removes any edges that are exactly the same color as the corner
7364pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
7365edges that are nearly the same color as the corner pixels.</p>
7366
7367<p>The page or virtual canvas information of the image is preserved allowing
7368you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
7369image. Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
7370information if it is unwanted.</p>
7371
7372<p>If the trimmed image 'disappears' an warning is produced, and a special
7373single pixel transparent 'missed' image is returned, in the same way as when a
7374<a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
7375
7376
7377<div style="margin: auto;">
7378 <h3 class="magick-header"><a id="type"></a>-type <var>type</var></h3>
7379</div>
7380
7381<p class="magick-description">the image type.</p> <p>Choose from: <code>Bilevel</code>,
7382<code>Grayscale</code>, <code>GrayscaleMatte</code>, <code>Palette</code>,
7383<code>PaletteMatte</code>, <code>TrueColor</code>, <code>TrueColorMatte</code>,
7384<code>ColorSeparation</code>, or <code>ColorSeparationMatte</code>.</p>
7385
7386<p>Normally, when a format supports different subformats such as grayscale and
7387truecolor, the encoder will try to choose an efficient subformat. The <a href="command-line-options.html#type">-type</a> option can be used to override this behavior. For
7388example, to prevent a JPEG from being written in grayscale format even though
7389only gray pixels are present, use.</p>
7390
7391<pre>
7392convert bird.png -type TrueColor bird.jpg
7393</pre>
7394
7395<p>Similarly, use <a href="command-line-options.html#type">-type TrueColorMatte</a> to force the
7396encoder to write an alpha channel even though the image is opaque, if the
7397output format supports transparency.</p>
7398
7399<p>Use <a href="command-line-options.html#type">-type optimize</a> to ensure the image is written in the smallest possible file size.</p>
7400
7401<div style="margin: auto;">
7402 <h3 class="magick-header"><a id="undercolor"></a>-undercolor <var>color</var></h3>
7403</div>
7404
7405<p class="magick-description">set the color of the annotation bounding box.</p>
7406
7407<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7408
7409<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7410
7411
7412<div style="margin: auto;">
7413 <h3 class="magick-header"><a id="update"></a>-update <var>seconds</var></h3>
7414</div>
7415
7416<p class="magick-description">detect when image file is modified and redisplay.</p>
7417
7418<p>Suppose that while you are displaying an image the file that is currently
7419displayed is over-written. <code>display</code> will automagically detect that
7420the input file has been changed and update the displayed image
7421accordingly.</p>
7422
7423
7424<div style="margin: auto;">
7425 <h3 class="magick-header"><a id="unique-colors"></a>-unique-colors</h3>
7426</div>
7427
7428<p class="magick-description">discard all but one of any pixel color.</p>
7429
7430
7431<div style="margin: auto;">
7432 <h3 class="magick-header"><a id="units"></a>-units <var>type</var></h3>
7433</div>
7434
7435<p class="magick-description">the units of image resolution.</p>
7436
7437<p>Choose from: <code>Undefined</code>, <code>PixelsPerInch</code>, or
7438<code>PixelsPerCentimeter</code>. This option is normally used in conjunction
7439with the <a href="command-line-options.html#density">-density</a> option.</p>
7440
7441
7442<div style="margin: auto;">
7443 <h3 class="magick-header"><a id="unsharp"></a>-unsharp <var>radius</var><br>-unsharp <var>radius</var>x<var>sigma</var>{<var>+gain</var>}{<var>+threshold</var>}</h3>
7444</div>
7445
7446<p class="magick-description">sharpen the image with an unsharp mask operator.</p>
7447
7448<p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
7449convolved with a Gaussian operator of the given radius and standard deviation
7450(sigma). For reasonable results, radius should be larger than sigma. Use
7451a radius of 0 to have the method select a suitable radius.</p>
7452
7453<p>The parameters are:</p>
7454
7455<dl class="dl-horizontal">
7456<dt>radius</dt>
7457<dd>The radius of the Gaussian, in pixels, not counting the center pixel (default 0).</dd>
7458<dt>sigma</dt>
7459<dd>The standard deviation of the Gaussian, in pixels (default 1.0).</dd>
7460<dt>gain</dt>
7461<dd>The fraction of the difference between the original and the blur image that is added back into the original (default 1.0).</dd>
7462<dt>threshold</dt>
7463<dd>The threshold, as a fraction of <var>QuantumRange</var>, needed to apply the difference amount (default 0.05).</dd>
7464</dl>
7465
7466<div style="margin: auto;">
7467 <h3 class="magick-header"><a id="verbose"></a>-verbose</h3>
7468</div>
7469
7470<p class="magick-description">print detailed information about the image when this option precedes the <a href="command-line-options.html#identify">-identify</a> option or <code>info:</code>.</p>
7471
7472
7473<div style="margin: auto;">
7474 <h3 class="magick-header"><a id="version"></a>-version</h3>
7475</div>
7476
7477<p class="magick-description">print ImageMagick version string and exit.</p>
7478
7479
7480<div style="margin: auto;">
7481 <h3 class="magick-header"><a id="view"></a>-view <var>string</var></h3>
7482</div>
7483
7484<p class="magick-description">FlashPix viewing parameters.</p>
7485
7486
7487<div style="margin: auto;">
7488 <h3 class="magick-header"><a id="vignette"></a>-vignette <var>radius</var>{x<var>sigma</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var>{<var>%</var>}</h3>
7489</div>
7490
7491<p class="magick-description">soften the edges of the image in vignette style.</p>
7492
7493<p>The vignette effect rolloff is controlled by radiusxsigma. For nominal rolloff, this would be set to 0xsigma. A value of 0x0 will produce a circle/ellipse with no rolloff. The arguments x and y control the size of the circle. Larger values decrease the radii and smaller values increase the radii. Values of +0+0 will generate a circle/ellipse the same size as the image. The default values for x and y are 10% of the corresponding image dimension. Thus, the radii will be decreased by 10%, i.e., the diameters of the circle/ellipse will be 80% of the corresponding image dimension.</p>
7494
7495<div style="margin: auto;">
7496 <h3 class="magick-header"><a id="virtual-pixel"></a>-virtual-pixel <var>method</var></h3>
7497</div>
7498
7499<p class="magick-description">Specify contents of <var>virtual pixels</var>.</p>
7500
7501<p>This option defines what color source should be used if and when a color
7502lookup completely 'misses' the source image. The color(s) that appear to
7503surround the source image. Generally this color is derived from the source
7504image, but could also be set to a specify background color. </p>
7505
7506<p>Choose from these methods:</p>
7507
7508<dl class="dl-horizontal">
7509<dt>background</dt><dd>the area surrounding the image is the background color</dd>
7510<dt>black</dt><dd>the area surrounding the image is black</dd>
7511<dt>checker-tile</dt><dd>alternate squares with image and background color</dd>
7512<dt>dither</dt><dd>non-random 32x32 dithered pattern</dd>
7513<dt>edge</dt><dd>extend the edge pixel toward infinity</dd>
7514<dt>gray</dt><dd>the area surrounding the image is gray</dd>
7515<dt>horizontal-tile</dt><dd>horizontally tile the image, background color above/below</dd>
7516<dt>horizontal-tile-edge</dt><dd>horizontally tile the image and replicate the side edge pixels</dd>
7517<dt>mirror</dt><dd>mirror tile the image</dd>
7518<dt>random</dt><dd>choose a random pixel from the image</dd>
7519<dt>tile</dt><dd>tile the image (default)</dd>
7520<dt>transparent</dt><dd>the area surrounding the image is transparent blackness</dd>
7521<dt>vertical-tile</dt><dd>vertically tile the image, sides are background color</dd>
7522<dt>vertical-tile-edge</dt><dd>vertically tile the image and replicate the side edge pixels</dd>
7523<dt>white</dt><dd>the area surrounding the image is white</dd>
7524</dl>
7525
7526<p>The default value is "edge".</p>
7527
7528<p>This most important for distortion operators such as <a href="command-line-options.html#distort">-distort</a>, <a href="command-line-options.html#implode">-implode</a>, and <a href="command-line-options.html#fx">-fx</a>.
7529However it also effects operations that may access pixels just outside the
7530image proper, such as <a href="command-line-options.html#convolve">-convolve</a>, <a href="command-line-options.html#blur">-blur</a>, and <a href="command-line-options.html#sharpen">-sharpen</a>. </p>
7531
7532<p>To print a complete list of virtual pixel types, use the <a href="command-line-options.html#list">-list virtual-pixel</a> option.</p>
7533
7534
7535<div style="margin: auto;">
7536 <h3 class="magick-header"><a id="visual"></a>-visual <var>type</var></h3>
7537</div>
7538
7539<p class="magick-description">Animate images using this X visual type.", 'animate', 'display'</p>
7540
7541<p>Choose from these visual classes:</p>
7542
7543<pre>
7544StaticGray TrueColor
7545GrayScale DirectColor
7546StaticColor default
7547PseudoColor visual id
7548</pre>
7549
7550<p>The X server must support the visual you choose, otherwise an error occurs.
7551If a visual is not specified, the visual class that can display the most
7552simultaneous colors on the default screen is chosen.</p>
7553
7554
7555<div style="margin: auto;">
7556 <h3 class="magick-header"><a id="watermark"></a>-watermark <var>brightness</var>x<var>saturation</var></h3>
7557</div>
7558
7559<p class="magick-description">Watermark an image using the given percentages of brightness and saturation.</p>
7560
7561<p>Take a grayscale image (with alpha mask) and modify the destination image's
7562brightness according to watermark image's grayscale value and the
7563<var>brightness</var> percentage. The destinations color saturation
7564attribute is just direct modified by the <var>saturation</var>
7565percentage, which defaults to 100 percent (no color change). </p>
7566
7567
7568<div style="margin: auto;">
7569 <h3 class="magick-header"><a id="wave"></a>-wave <var>amplitude</var><br>-wave <var>amplitude</var>x<var>wavelength</var></h3>
7570</div>
7571
7572<p class="magick-description">Shear the columns of an image into a sine wave.</p>
7573
7574<p>Specify <var>amplitude</var> and <var>wavelength</var>
7575of the wave.</p>
7576
7577<div style="margin: auto;">
7578 <h3 class="magick-header"><a id="weight"></a>-weight <var>fontWeight</var></h3>
7579</div>
7580
7581<p class="magick-description">Set a font weight for text.</p>
7582
7583<p>This setting suggests a font weight that ImageMagick should try to apply to
7584the currently selected font family. Use a positive integer for
7585<var>fontWeight</var> or select from the following.</p>
7586
7587<dl class="dl-horizontal">
7588<dt>Thin </dt>
7589<dd>Same as <var>fontWeight</var> = 100.</dd>
7590<dt>ExtraLight </dt>
7591<dd>Same as <var>fontWeight</var> = 200.</dd>
7592<dt>Light </dt>
7593<dd>Same as <var>fontWeight</var> = 300.</dd>
7594<dt>Normal </dt>
7595<dd>Same as <var>fontWeight</var> = 400.</dd>
7596<dt>Medium </dt>
7597<dd>Same as <var>fontWeight</var> = 500.</dd>
7598<dt>DemiBold </dt>
7599<dd>Same as <var>fontWeight</var> = 600.</dd>
7600<dt>Bold </dt>
7601<dd>Same as <var>fontWeight</var> = 700.</dd>
7602<dt>ExtraBold </dt>
7603<dd>Same as <var>fontWeight</var> = 800.</dd>
7604<dt>Heavy </dt>
7605<dd>Same as <var>fontWeight</var> = 900.</dd>
7606</dl>
7607<br>
7608
7609<p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list weight</a>.</p>
7610
7611<p>For other settings that affect fonts, see the options <a href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#style">-style</a>. </p>
7612
7613<div style="margin: auto;">
7614 <h3 class="magick-header"><a id="white-point"></a>-white-point <var>x,y</var></h3>
7615</div>
7616
7617<p class="magick-description">chromaticity white point.</p>
7618
7619<div style="margin: auto;">
7620 <h3 class="magick-header"><a id="white-threshold"></a>-white-threshold <var>value</var>{<var>%</var>}</h3>
7621</div>
7622
7623<p class="magick-description">Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged.</p>
7624
7625<p> The threshold value can be given as a percentage or as an absolute integer
7626value within [0, <var>QuantumRange</var>] corresponding to the
7627desired <a href="command-line-options.html#channel">‑channel</a> value. See <a href="command-line-options.html#threshold">‑threshold</a>for more details on thresholds and resulting values. </p>
7628
7629<div style="margin: auto;">
7630 <h3 class="magick-header"><a id="window"></a>-window <var>id</var></h3>
7631</div>
7632
7633<p class="magick-description">Make the image the background of a window.", 'animate', 'display'</p>
7634
7635<p><var>id</var> can be a window id or name. Specify <code>root</code>
7636to select X's root window as the target window.</p>
7637
7638<p>By default the image is tiled onto the background of the target window. If
7639<code>backdrop</code> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
7640image is surrounded by the background color. Refer to <code>X RESOURCES</code>
7641for details.</p>
7642
7643<p>The image will not display on the root window if the image has more unique
7644colors than the target window colormap allows. Use <a href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
7645
7646<div style="margin: auto;">
7647 <h3 class="magick-header"><a id="window-group"></a>-window-group</h3>
7648</div>
7649
7650<p class="magick-description">specify the window group.</p>
7651
7652<div style="margin: auto;">
7653 <h3 class="magick-header"><a id="write"></a>-write <var>filename</var></h3>
7654</div>
7655
7656<p class="magick-description">write an image sequence.</p>
7657
7658<p>The image sequence preceding the <a href="command-line-options.html#write">-write</a> <var>filename</var> option is written out, and processing continues with the same image in its current state if there are additional options. To restore the image to its original state after writing it, use the <a href="command-line-options.html#write">+write</a> <var>filename</var> option.</p>
7659
7660<p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
7661</div>
7662</div>
7663
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