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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 behavior 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
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
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
1351magnitude-phase
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
1711 grayscale. This should be accompanied by -type truecolor. PNG and TIF do
1712 not need this define. With PNG, just use PNG24:image. With TIF, just use
1713 -type truecolor. JPG and PSD will need this define.</td>
1714 </tr>
1715
1716 <tr>
1717 <td>complex:snr=<var>value</var></td>
1718 <td>Set the divide SNR constant<a href="command-line-options.html#complex">-complex</a></td>
1719 </tr>
1720
1721 <tr>
1722 <td>compose:args=<var>arguments</var></td>
1723 <td>Sets certain compose argument values when using convert ... -compose ...
1724 -composite. See <a href="http://www.imagemagick.org/www/compose.html">Image Composition</a></td>
1725 </tr>
1726
1727 <tr>
1728 <td>compose:clamp=<var>on|off</var></td>
1729 <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>
1730 </tr>
1731
1732 <tr>
1733 <td>convolve:scale=<var>{kernel_scale}[!^] [,{origin_addition}] [%]</var></td>
1734 <td>Defines the kernel scaling. The special flag ! automatically scales to
1735 full dynamic range. The ! flag can be used in combination with a factor or
1736 percent. The factor or percent is then applied after the automatic scaling.
1737 An example is 50%!. This produces a result 50% darker than full dynamic
1738 range scaling. The ^ flag assures the kernel is 'zero-summing', for
1739 example when some values are positive and some are negative as in edge
1740 detection kernels. The origin addition adds that value to the center
1741 pixel of the kernel. This produces and effect that is like adding the image
1742 that many times to the result of the filtered image. The typical value
1743 is 1 so that the original image is added to the result of the convolution.
1744 The default is 0.</td>
1745 </tr>
1746
1747 <tr>
1748 <td>convolve:showkernel=<var>1</var></td>
1749 <td>Outputs (to 'standard error') all the information about a specified <a href="command-line-options.html#morphology">-morphology convolve</a> kernel.</td>
1750 </tr>
1751
1752 <tr>
1753 <td>dcm:display-range=<var>reset</var></td>
1754 <td>Sets the display range to the minimum and maximum pixel values for the
1755 DCM image format.</td>
1756 </tr>
1757
1758 <tr>
1759 <td>dds:cluster-fit=<var>true|false</var></td>
1760 <td>Enables the dds cluster-fit.</td>
1761 </tr>
1762
1763 <tr>
1764 <td>dds:compression=<var>dxt1|dxt5|none</var></td>
1765 <td>Sets the dds compression.</td>
1766 </tr>
1767
1768 <tr>
1769 <td>dds:mipmaps=<var>value</var></td>
1770 <td>Sets the dds number of mipmaps.</td>
1771 </tr>
1772
1773 <tr>
1774 <td>dds:weight-by-alpha=<var>true|false</var></td>
1775 <td>Enables the dds alpha weighting.</td>
1776 </tr>
1777
1778 <tr>
1779 <td>delegate:bimodal=<var>true</var></td>
1780 <td>Specifies direct conversion from Postscript to PDF.</td>
1781 </tr>
1782
1783 <tr>
1784 <td>distort:scale=<var>value</var></td>
1785 <td>Sets the output scaling factor for use with <a href="command-line-options.html#distort">-distort</a></td>
1786 </tr>
1787
1788 <tr>
1789 <td>distort:viewport=<var>WxH+X+Y</var></td>
1790 <td>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a></td>
1791 </tr>
1792
1793 <tr>
1794 <td>dot:layout-engine=<var>value</var></td>
1795 <td>Specifies the layout engine for the DOT image format (e.g.
1796 <code>neato</code>).</td>
1797 </tr>
1798
1799 <tr>
1800 <td>filter:option=<var>value</var></td>
1801 <td>Set a filter option for use with <a href="command-line-options.html#resize">-resize</a>.
1802 See <a href="command-line-options.html#filter">-filter</a> for details.</td>
1803 </tr>
1804
1805 <tr>
1806 <td>fourier:normalize=<var>inverse</var></td>
1807 <td>Sets the location for the FFT/IFT normalization as use by
1808 <a href="command-line-options.html#fft">+-fft</a> and <a href="command-line-options.html#ift">+-ift</a>. The default is
1809 <var>forward</var>.</td>
1810 </tr>
1811
1812 <tr>
1813 <td>h:format=<var>value</var></td>
1814 <td>Set the image encoding format use when writing a C-style header.
1815 <var>format</var> can be any output format supported by ImageMagick
1816 except for <var>h</var> and <var>magick</var></td>. If this
1817 option is omitted, the default is <var>GIF</var> for PseudoClass
1818 images and <var>PNM</var> for DirectClass images.
1819 </tr>
1820
1821 <tr>
1822 <td>icon:auto-resize</td>
1823 <td>Automatically stores multiple sizes when writing an ico image
1824 (requires a 256x256 input image).</td>
1825 </tr>
1826
1827 <tr>
1828 <td>jp2:layer-number=<var>value</var></td>
1829 <td>Sets the maximum number of quality layers to decode. Same for JPT, JC2,
1830 and J2K</td>
1831 </tr>
1832
1833 <tr>
1834 <td>jp2:number-resolutions=<var>value</var></td>
1835 <td>Sets the number of resolutions to encode.Same for JPT, JC2, and J2K</td>
1836 </tr>
1837
1838 <tr>
1839 <td>jp2:progression-order=<var>value</var></td>
1840 <td>choose from LRCP, RLCP, RPCL, PCRL or CPRL. Same for JPT, JC2, and
1841 J2K</td>
1842 </tr>
1843
1844 <tr>
1845 <td>jp2:quality=<var>value,value...</var></td>
1846 <td>Sets the quality layer PSNR, given in dB. The order is from left to
1847 right in ascending order. The default is a single lossless quality layer.
1848 Same for JPT, JC2, and J2K</td>
1849 </tr>
1850
1851 <tr>
1852 <td>jp2:rate=<var>value</var></td>
1853 <td>Specify the compression factor to use while writing JPEG-2000 files. The
1854 compression factor is the reciprocal of the compression ratio. The valid
1855 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined,
1856 this value overrides the -quality setting. A quality setting of 75
1857 results in a rate value of 0.06641. Same for JPT, JC2, and J2K</td>
1858 </tr>
1859
1860 <tr>
1861 <td>jp2:reduce-factor=<var>value</var></td>
1862 <td>Sets the number of highest resolution levels to be discarded.Same for
1863 JPT, JC2, and J2K</td>
1864 </tr>
1865
1866 <tr>
1867 <td>jpeg:block-smoothing=<var>on|off</var></td>
1868 <td>&amp;nbsp</td>
1869 </tr>
1870
1871 <tr>
1872 <td>jpeg:colors=<var>value</var></td>
1873 <td>Set the desired number of colors and let the JPEG encoder do the
1874 quantizing.</td>
1875 </tr>
1876
1877 <tr>
1878 <td>jpeg:dct-method=<var>value</var></td>
1879 <td>Choose from <code>default</code>, <code>fastest</code>,
1880 <code>float</code>, <code>ifast</code>, and <code>islow</code>.</td>
1881 </tr>
1882
1883 <tr>
1884 <td>jpeg:extent=<var>value</var></td>
1885 <td>Restrict the maximum JPEG file size, for example <code>-define
1886 jpeg:extent=400KB</code>. The JPEG encoder will search for the highest
1887 compression quality level that results in an output file that does not
1888 exceed the value. The <code>-quality</code> option is ignored if it
1889 is also present.</td>
1890 </tr>
1891
1892 <tr>
1893 <td>jpeg:fancy-upsampling=<var>on|off</var></td>
1894 <td>&amp;nbsp</td>
1895 </tr>
1896
1897 <tr>
1898 <td>jpeg:optimize-coding=<var>on|off</var></td>
1899 <td>&amp;nbsp</td>
1900 </tr>
1901
1902 <tr>
1903 <td>jpeg:q-table=<var>table</var></td>
1904 <td>&amp;nbsp</td>
1905 </tr>
1906
1907 <tr>
1908 <td>jpeg:sampling-factor=<var>sampling-factor-string</var></td>
1909 <td>&amp;nbsp</td>
1910 </tr>
1911
1912 <tr>
1913 <td>jpeg:size=<var>geometry</var></td>
1914 <td>Set the size hint of a JPEG image, for
1915 example, <code>-define jpeg:size=128x128</code>.
1916 It is most useful for increasing performance and reducing the memory
1917 requirements when reducing the size of a large JPEG image.</td>
1918 </tr>
1919
1920 <tr>
1921 <td>json:features</td>
1922 <td>includes features in verbose information</td>
1923 </tr>
1924
1925 <tr>
1926 <td>json:limit</td>
1927 <td>&amp;nbsp</td>
1928 </tr>
1929
1930 <tr>
1931 <td>json:locate</td>
1932 <td>&amp;nbsp</td>
1933 </tr>
1934
1935 <tr>
1936 <td>json:moments</td>
1937 <td>includes image moments in verbose information</td>
1938 </tr>
1939
1940 <tr>
1941 <td>magick:format=<var>value</var></td>
1942 <td>Set the image encoding format use when writing a C-style header.
1943 This is the same as "h:format=format" described above.</td>.
1944 </tr>
1945
1946 <tr>
1947 <td>mng:need-cacheoff</td>
1948 <td>turn playback caching off for streaming MNG.</td>
1949 </tr>
1950
1951 <tr>
1952 <td>morphology:compose=<var>compose-method</var></td>
1953 <td>Specifies how to merge results generated by multiple<a href="command-line-options.html#morphology">-morphology</a> kernel. The default is none. One
1954 typical value is 'lighten' as used, for example, with the sobel edge
1955 kernels. </td>
1956 </tr>
1957
1958 <tr>
1959 <td>morphology:showkernel=<var>1</var></td>
1960 <td>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</td>
1961 </tr>
1962
1963 <tr>
1964 <td>pcl:fit-to-page=<var>true</var></td>
1965
1966 </tr><tr>
1967 <td>pdf:fit-page=<var>geometry</var></td>
1968 <td> geometry specifies the scaling dimensions for resizing when the PDF is
1969 being read. The geometry is either WxH{%} or page size. No offsets are
1970 allowed. (introduced in IM 6.8.8-8)</td>
1971 </tr>
1972
1973 <tr>
1974 <td>pdf:fit-to-page=<var>true</var></td>
1975 <td>&amp;nbsp</td>
1976 </tr>
1977
1978 <tr>
1979 <td>pdf:use-cropbox=<var>true</var></td>
1980 <td>&amp;nbsp</td>
1981 </tr>
1982
1983 <tr>
1984 <td>pdf:use-trimbox=<var>true</var></td>
1985 <td>&amp;nbsp</td>
1986 </tr>
1987
1988 <tr>
1989 <td>png:bit-depth=<var>value</var></td>
1990 <td>&amp;nbsp</td>
1991 </tr>
1992 <tr>
1993 <td>png:color-type=<var>value</var></td>
1994 <td>desired bit-depth and color-type for PNG output. You can force the PNG
1995 encoder to use a different bit-depth and color-type than it would have
1996 normally selected, but only if this does not cause any loss of image
1997 quality. Any attempt to reduce image quality is treated as an error and no
1998 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
1999 can use these "defines" to cause it to be written as an 8-bit grayscale,
2000 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
2001 you cannot force it to be written as a grayscale or indexed PNG. If you
2002 wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
2003 <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
2004 reduce the image quality prior to using the PNG encoder. Note that in
2005 indexed PNG files, "bit-depth" refers to the number of bits per index,
2006 which can be 1, 2, 4, or 8. In such files, the color samples always have
2007 8-bit depth.</td>
2008 </tr>
2009
2010 <tr>
2011 <td>png:compression-filter=<var>value</var></td>
2012 <td> valid values are 0 through 9. 0-4 are the corresponding PNG filters,
2013 5 means adaptive filtering except for images with a colormap, 6 means
2014 adaptive filtering for all images, 7 means MNG "loco" compression, 8 means
2015 Z_RLE strategy with adaptive filtering, and 9 means Z_RLE strategy with no
2016 filtering.</td>
2017 </tr>
2018
2019 <tr>
2020 <td>png:compression-level=<var>value</var></td>
2021 <td> valid values are 0 through 9, with 0 providing the least but fastest
2022 compression and 9 usually providing the best and always the slowest.</td>
2023 </tr>
2024
2025 <tr>
2026 <td>png:compression-strategy=<var>value</var></td>
2027 <td> valid values are 0 through 4, meaning default, filtered, huffman_only,
2028 rle, and fixed ZLIB compression strategy. If you are using an old zlib
2029 that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
2030 values 3 and 4, respectively, will use the zlib default strategy
2031 instead.</td>
2032 </tr>
2033
2034 <tr>
2035 <td>png:format=<var>value</var></td>
2036 <td> valid values are <var>png8</var>, <var>png24</var>,
2037 <var>png32</var>, <var>png48</var>,
2038 <var>png64</var>, and <var>png00</var>.
2039 This property can be useful for specifying
2040 the specific PNG format to be used, when the usual method of prepending the
2041 format name to the output filename is inconvenient, such as when writing
2042 a PNG-encoded ICO file or when using <a href="mogrify.html">mogrify</a>.
2043 Value = <var>png8</var> reduces the number of colors to 256,
2044 only one of which may be fully transparent, if necessary. The other
2045 values do not force any reduction of quality; it is an error to request
2046 a format that cannot represent the image data without loss (except that
2047 it is allowed to reduce the bit-depth from 16 to 8 for all formats).
2048 Value = <var>png24</var> and <var>png48</var>
2049 allow transparency, only if a single color is fully transparent and that
2050 color does not also appear in an opaque pixel; such transparency is
2051 written in a PNG <code>tRNS</code> chunk.
2052 Value = <var>png00</var> causes the image to inherit its
2053 color-type and bit-depth from the input image, if the input was also
2054 a PNG.</td>
2055 </tr>
2056
2057 <tr>
2058 <td>png:exclude-chunk=<var>value</var></td>
2059
2060 </tr><tr>
2061 <td>png:include-chunk=<var>value</var></td>
2062 <td>ancillary chunks to be excluded from or included in PNG output.
2063
2064 <p>The <var>value</var> can be the name of a PNG chunk-type such
2065 as <var>bKGD</var>, a comma-separated list of chunk-names
2066 (which can include the word <var>date</var>, the word
2067 <var>all</var>, or the word <var>none</var>).
2068 Although PNG chunk-names are case-dependent, you can use all lowercase
2069 names if you prefer.</p>
2070
2071 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
2072 of the PNG encoder and have no effect on the PNG decoder.</p>
2073
2074 <p>As a special case, if the <code>sRGB</code> chunk is excluded and
2075 the <code>gAMA</code> chunk is included, the <code>gAMA</code> chunk will
2076 only be written if gamma is not 1/2.2, since most decoders assume
2077 sRGB and gamma=1/2.2 when no colorspace information is included in
2078 the PNG file. Because the list is processed from left to right, you
2079 can achieve this with a single define:</p>
2080
2081<pre>
2082-define png:include-chunk=none,gAMA
2083</pre>
2084
2085 <p>As a special case, if the <code>sRGB</code> chunk is not excluded and
2086 the PNG encoder recognizes that the image contains the sRGB ICC profile,
2087 the PNG encoder will write the <code>sRGB</code> chunk instead of the
2088 entire ICC profile. To force the PNG encoder to write the sRGB
2089 profile as an <code>iCCP</code> chunk in the output PNG instead of the
2090 <code>sRGB</code> chunk, exclude the <code>sRGB</code> chunk.</p>
2091
2092 <p>The critical PNG chunks <code>IHDR</code>, <code>PLTE</code>,
2093 <code>IDAT</code>, and <code>IEND</code> cannot be excluded. Any such
2094 entries appearing in the list will be ignored.</p>
2095
2096 <p>If the ancillary PNG <code>tRNS</code> chunk is excluded and the
2097 image has transparency, the PNG colortype is forced to be 4 or 6
2098 (GRAY_ALPHA or RGBA). If the image is not transparent, then the
2099 <code>tRNS</code> chunk isn't written anyhow, and there is no effect
2100 on the PNG colortype of the output image.</p>
2101
2102 <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2103 following for PNG output:</p>
2104
2105<pre>
2106-define png:exclude-chunk=EXIF,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date
2107</pre>
2108
2109 <p>The default behavior is to include all known PNG ancillary chunks
2110 plus ImageMagick's private <code>vpAg</code> ("virtual page") chunk,
2111 and to exclude all PNG chunks that are unknown to ImageMagick,
2112 regardless of their PNG "copy-safe" status as described in the
2113 PNG specification.</p>
2114
2115 <p>Any chunk names that are not known to ImageMagick are ignored
2116 if they appear in either the "include-chunk" or "exclude-chunk" list.
2117 The ancillary chunks currently known to ImageMagick are
2118 <code>bKGD</code>, <code>cHRM</code>, <code>gAMA</code>, <code>iCCP</code>,
2119 <code>oFFs</code>, <code>pHYs</code>, <code>sRGB</code>, <code>tEXt</code>,
2120 <code>tRNS</code>, <code>vpAg</code>, and <code>zTXt</code>.</p>
2121
2122 <p>You can also put <code>date</code> in the list to include or exclude
2123 the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2124 inserts in the output PNG.</p></td>
2125 </tr>
2126
2127 <tr>
2128 <td>png:preserve-colormap[=<var>true</var>]</td>
2129 <td>Use the existing image-&gt;colormap. Normally the PNG encoder will
2130 try to optimize the palette, eliminating unused entries and putting
2131 the transparent colors first. If this flag is set, that behavior
2132 is suppressed.</td>
2133 </tr>
2134
2135 <tr>
2136 <td>png:preserve-iCCP[=<var>true</var>]</td>
2137 <td>By default, the PNG decoder and encoder examine any ICC profile
2138 that is present, either from an <code>iCCP</code> chunk in the PNG
2139 input or supplied via an option, and if the profile is recognized
2140 to be the sRGB profile, converts it to the <code>sRGB</code> chunk.
2141 You can use <code>-define png:preserve-iCCP</code> to prevent
2142 this from happening; in such cases the <code>iCCP</code> chunk
2143 will be read or written and no <code>sRGB</code> chunk will be
2144 written. There are some ICC profiles that claim to be sRGB but
2145 have various errors that cause them to be rejected by libpng16; such
2146 profiles are recognized anyhow and converted to the <code>sRGB</code>
2147 chunk, but are rejected if the <code>-define png:preserve-iCCP</code>
2148 is present. Note that not all "sRGB" ICC profiles are recognized
2149 yet; we will add them to the list as we encounter them.</td>
2150 </tr>
2151
2152 <tr>
2153 <td>png:swap-bytes[=<var>true</var>]</td>
2154 <td>The PNG specification requires that any multi-byte integers be stored in
2155 network byte order (MSB-LSB endian). This option allows you to
2156 fix any invalid PNG files that have 16-bit samples stored incorrectly
2157 in little-endian order (LSB-MSB). The "-define png:swap-bytes" option
2158 must appear before the input filename on the commandline. The swapping
2159 is done during the libpng decoding operation.</td>
2160 </tr>
2161
2162 <tr>
2163 <td>profile:skip=<var>name1,name2,...</var></td>
2164 <td>Skip the named profile[s] when reading the image. Use skip="*" to
2165 skip all named profiles in the image. Many named profiles exist,
2166 including ICC, EXIF, APP1, IPTC, XMP, and others.</td>
2167 </tr>
2168
2169 <tr>
2170 <td>ps:imagemask</td>
2171 <td>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will
2172 create Postscript files that render bilevel images with the Postscript
2173 imagemask operator instead of the image operator.</td>
2174 </tr>
2175
2176 <tr>
2177 <td>psd:alpha-unblend=off</td>
2178 <td>Disables new automatic un-blending of transparency with the base image
2179 for the flattened layer 0 before adding the alpha channel to the output
2180 image. This define must be placed before the input psd image. (Available
2181 as of IM 6.9.2.5). The automatic un-blending is new to IM 6.9.2.5 and
2182 prevents the transparency from being applied twice in the output
2183 image.</td>
2184 </tr>
2185
2186 <tr>
2187 <td>quantum:format=<var>type</var></td>
2188 <td>Set the type to <code>floating-point</code> to specify a floating-point
2189 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2190 to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2191 included, the result is a single precision floating point format.
2192 If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2193 double precision floating point format.</td>
2194 </tr>
2195
2196 <tr>
2197 <td>quantum:polarity=<var>photometric-interpretation</var></td>
2198 <td>Set the photometric-interpretation of an image (typically for TIFF image
2199 file format) to either <code>min-is-black</code> (default) or
2200 <code>min-is-white</code>.</td>
2201 </tr>
2202
2203 <tr>
2204 <td>sample:offset=<var>geometry</var></td>
2205 <td>Location of the sampling point within the sub-region being sampled,
2206 expressed as percentages (see <a href="command-line-options.html#sample">-sample</a>).</td>
2207 </tr>
2208
2209 <tr>
2210 <td>showkernel=<var>1</var></td>
2211 <td>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</td>
2212 </tr>
2213
2214 <tr>
2215 <td>stream:buffer-size=<var>value</var></td>
2216 <td>Set the stream buffer size. Select 0 for unbuffered I/O.</td>
2217 </tr>
2218
2219 <tr>
2220 <td>tiff:alpha=<var>associated|unassociated|unspecified</var></td>
2221 <td>Specify the alpha extra samples as associated, unassociated or unspecified </td>
2222 </tr>
2223
2224 <tr>
2225 <td>tiff:endian=<var>msb|lsb</var></td>
2226 <td>&amp;nbsp</td>
2227 </tr>
2228
2229 <tr>
2230 <td>tiff:exif-properties=<var>false</var></td>
2231 <td>Skips reading the EXIF properties.</td>
2232 </tr>
2233
2234 <tr>
2235 <td>tiff:fill-order=<var>msb|lsb</var></td>
2236 <td>&amp;nbsp</td>
2237 </tr>
2238
2239 <tr>
2240 <td>tiff:ignore-layers=<var>true</var></td>
2241 <td>Ignores the photoshop layers.</td>
2242 </tr>
2243
2244 <tr>
2245 <td>tiff:ignore-tags=<var>comma-separate-list-of-tag-IDs</var></td>
2246 <td>Allows one or more tag ID values to be ignored.</td>
2247 </tr>
2248
2249 <tr>
2250 <td>tiff:rows-per-strip=<var>value</var></td>
2251 <td>Sets the number of rows per strip</td>
2252 </tr>
2253
2254 <tr>
2255 <td>tiff:tile-geometry=<var>WxH</var></td>
2256 <td>Sets the tile size for pyramid tiffs. Requires the suffix
2257 PTIF: before the outputname</td>
2258 </tr>
2259</table>
2260
2261<p>For example, to create a postscript file that will render only the black
2262pixels of a bilevel image, use:</p>
2263
2264<pre>
2265convert bilevel.tif -define ps:imagemask eps3:stencil.ps
2266</pre>
2267
2268<p>Set attributes of the image registry by prefixing the value with
2269<code>registry:</code>. For example, to set a temporary path to put work files,
2270use:</p>
2271
2272<pre>
2273-define registry:temporary-path=/data/tmp
2274</pre>
2275
2276<div style="margin: auto;">
2277 <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>
2278</div>
2279
2280<p class="magick-description">display the next image after pausing.</p>
2281
2282<p>This option is useful for regulating the animation of image sequences
2283<var>ticks/ticks-per-second</var> seconds must expire before the display of the
2284next image. The default is no delay between each showing of the image
2285sequence. The default ticks-per-second is 100.</p>
2286
2287<p>Use <code>&gt;</code> to change the image delay <var>only</var> if its current
2288value exceeds the given delay. <code>&lt;</code> changes the image delay
2289<var>only</var> if current value is less than the given delay. For example, if
2290you specify <code>30&gt;</code> and the image delay is 20, the image delay does
2291not change. However, if the image delay is 40 or 50, the delay it is changed
2292to 30. Enclose the given delay in quotation marks to prevent the
2293<code>&lt;</code> or <code>&gt;</code> from being interpreted by your shell as
2294a file redirection.</p>
2295
2296
2297<div style="margin: auto;">
2298 <h3 class="magick-header"><a id="delete"></a>-delete <var>indexes</var></h3>
2299</div>
2300
2301<p class="magick-description">delete the images specified by index, from the image sequence.</p>
2302
2303<p>Specify the image by its index in the sequence. The first image is index
23040. Negative indexes are relative to the end of the sequence, for example, -1
2305represents the last image of the sequence. Specify a range of images with
2306a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use
2307<code>+delete</code> to delete the last image in the current image sequence.</p>
2308
2309
2310<div style="margin: auto;">
2311 <h3 class="magick-header"><a id="density"></a>-density <var>width</var><br>-density <var>width</var>x<var>height</var></h3>
2312</div>
2313
2314<p class="magick-description">Set the horizontal and vertical resolution of an image for rendering to devices.</p>
2315
2316<p>This option specifies the image resolution to store while encoding a raster
2317image or the canvas resolution while rendering (reading) vector formats such
2318as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2319provides the unit of measure to apply when rendering to an output device or
2320raster 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
2321instead.</p>
2322
2323<p>The default resolution is 72 dots per inch, which is equivalent to one
2324point per pixel (Macintosh and Postscript standard). Computer screens are
2325normally 72 or 96 dots per inch, while printers typically support 150, 300,
2326600, or 1200 dots per inch. To determine the resolution of your display, use
2327a ruler to measure the width of your screen in inches, and divide by the
2328number of horizontal pixels (1024 on a 1024x768 display).</p>
2329
2330<p>If the file format supports it, this option may be used to update the
2331stored image resolution. Note that Photoshop stores and obtains image
2332resolution from a proprietary embedded profile. If this profile is not
2333stripped from the image, then Photoshop will continue to treat the image using
2334its former resolution, ignoring the image resolution specified in the standard
2335file header.</p>
2336
2337<p>The <a href="command-line-options.html#density">-density</a> option sets an <var>attribute</var> and
2338does not alter the underlying raster image. It may be used to adjust the
2339rendered size for desktop publishing purposes by adjusting the scale applied
2340to the pixels. To resize the image so that it is the same size at a different
2341resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2342
2343<div style="margin: auto;">
2344 <h3 class="magick-header"><a id="depth"></a>-depth <var>value</var></h3>
2345</div>
2346
2347<p class="magick-description">depth of the image.</p>
2348
2349<p>This the number of bits in a color sample within a pixel. Use this option
2350to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2351or CMYK, or to change the depth of any image after it has been read.</p>
2352
2353<div style="margin: auto;">
2354 <h3 class="magick-header"><a id="descend"></a>-descend</h3>
2355</div>
2356
2357<p class="magick-description">obtain image by descending window hierarchy.</p>
2358
2359<div style="margin: auto;">
2360 <h3 class="magick-header"><a id="deskew"></a>-deskew <var>threshold</var></h3>
2361</div>
2362
2363<p class="magick-description">straighten an image. A threshold of 40% works for most images.</p>
2364
2365<p>Use <a href="command-line-options.html#set">-set</a> <code>option:deskew:auto-crop
2366<var>width</var></code> to auto crop the image. The set argument is the pixel
2367width of the image background (e.g 40).</p>
2368
2369<div style="margin: auto;">
2370 <h3 class="magick-header"><a id="despeckle"></a>-despeckle</h3>
2371</div>
2372
2373<p class="magick-description">reduce the speckles within an image.</p>
2374
2375<div style="margin: auto;">
2376 <h3 class="magick-header"><a id="direction"></a>-direction <var>type</var></h3>
2377</div>
2378
2379<p class="magick-description">render text right-to-left or left-to-right.</p>
2380
2381<div style="margin: auto;">
2382 <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>
2383</div>
2384
2385<p class="magick-description">shift image pixels as defined by a displacement map.</p>
2386
2387<p>With this option, the 'overlay' image, and optionally the 'mask' image,
2388is used as a displacement map, which is used to displace the lookup of
2389what part of the 'background' image is seen at each point of the overlaid
2390area. Much like the displacement map is a 'lens' that redirects light shining
2391through it so as to present a distorted view the original 'background' image
2392behind it. </p>
2393
2394<p>Any perfect grey areas of the displacement map produce a zero
2395displacement of the image. Black areas produce the given maximum negative
2396displacement of the lookup point, while white produce a maximum positive
2397displacement of the lookup. </p>
2398
2399<p>Note that it is the lookup of the 'background' that is displaced, not a
2400displacement of the image itself. As such an area of the displacement map
2401containing 'white' will have the lookup point 'shifted' by a positive amount,
2402and thus generating a copy of the destination image to the right/downward from
2403the correct position. That is the image will look like it may have been
2404'shifted' in a negative left/upward direction. Understanding this is a very
2405important in understanding how displacement maps work. </p>
2406
2407<p>The given arguments define the maximum amount of displacement in pixels
2408that a particular map can produce. If the displacement scale is large enough
2409it is also possible to lookup parts of the 'background' image that lie well
2410outside the bounds of the displacement map itself. That is you could very
2411easily copy a section of the original image from outside the overlay area
2412into the overlay area. </p>
2413
2414<p>The '%' flag makes the displacement scale relative to the size of the
2415overlay image (100% = half width/height of image). Using '!' switches
2416percentage arguments to refer to the destination image size instead.
2417these flags were added as of IM v6.5.3-5.</p>
2418
2419<p>Normally a single grayscale displacement map is provided, which with the
2420given scaling values will determine a single direction (vector) in which
2421displacements can occur (positively or negatively). However, if you also
2422specify a third image which is normally used as a <var>mask</var>,
2423the <var>composite image</var> is used for horizontal X
2424displacement, while the <var>mask image</var> is used for vertical Y
2425displacement. This allows you to define completely different displacement
2426values for the X and Y directions, and allowing you to lookup any point within
2427the <var>scale</var> bounds. In other words each pixel can lookup
2428any other nearby pixel, producing complex 2 dimensional displacements, rather
2429than a simple 1 dimensional vector displacements. </p>
2430
2431<p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2432you can use the 'red' channel of the overlay image to specify the horizontal
2433or X displacement, and the 'green' channel for the vertical or Y displacement.
2434</p>
2435
2436<p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2437mask the transparency of the destination image. However areas outside the
2438overlaid areas will not be effected. </p>
2439
2440
2441<div style="margin: auto;">
2442 <h3 class="magick-header"><a id="display"></a>-display <var>host:display[.screen]</var></h3>
2443</div>
2444
2445<p class="magick-description">Specifies the X server to contact.</p>
2446
2447<p>This option is used with convert for obtaining image or font from this
2448X server. See <var>X(1)</var>.</p>
2449
2450<div style="margin: auto;">
2451 <h3 class="magick-header"><a id="dispose"></a>-dispose <var>method</var></h3>
2452</div>
2453
2454<p class="magick-description">define the GIF disposal image setting for images that are being created or read in. </p>
2455
2456<p>The layer disposal method defines the way each the displayed image is to be
2457modified after the current 'frame' of an animation has finished being
2458displayed (after its 'delay' period), but before the next frame on an
2459animation is to be overlaid onto the display. </p>
2460
2461<p>Here are the valid methods:</p>
2462
2463<dl class="dl-horizontal">
2464<dt>Undefined</dt><dd>0: No disposal specified (equivalent to '<code>none</code>').</dd>
2465<dt>None</dt><dd>1: Do not dispose, just overlay next frame image.</dd>
2466<dt>Background</dt><dd>2: Clear the frame area with the background color.</dd>
2467<dt>Previous</dt><dd>3: Clear to the image prior to this frames overlay.</dd>
2468</dl>
2469
2470<p>You can also use the numbers given above, which is what the GIF format
2471uses internally to represent the above settings. </p>
2472
2473<p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2474
2475<p>Use <a href="command-line-options.html#dispose">+dispose</a>, turn off the setting and prevent
2476resetting the layer disposal methods of images being read in. </p>
2477
2478<p>Use <a href="command-line-options.html#set">-set</a> '<code>dispose</code>' method to set the image
2479disposal method for images already in memory.</p>
2480
2481<div style="margin: auto;">
2482 <h3 class="magick-header"><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <var>value</var></h3>
2483</div>
2484
2485<p class="magick-description">maximum RMSE for subimage match (default 0.2).</p>
2486
2487
2488<div style="margin: auto;">
2489 <h3 class="magick-header"><a id="dissolve"></a>-dissolve <var>src_percent</var>[x<var>dst_percent</var>]</h3>
2490</div>
2491
2492<p class="magick-description">dissolve an image into another by the given percent.</p>
2493
2494<p>The opacity of the composite image is multiplied by the given percent, then
2495it is composited 'over' the main image. If <var>src_percent</var>
2496is greater than 100, start dissolving the main image so it becomes
2497transparent at a value of '<code>200</code>'. If both percentages
2498are given, each image are dissolved to the percentages given. </p>
2499
2500<p>Note that dissolve percentages do not add, two opaque images dissolved
2501'50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2502images, you would need to use dissolve values of '50,100'. </p>
2503
2504<div style="margin: auto;">
2505 <h3 class="magick-header"><a id="distort"></a>-distort <var>method arguments</var></h3>
2506</div>
2507
2508<p class="magick-description">distort an image, using the given <var>method</var> and its required <var>arguments</var>.</p>
2509
2510<p>The <var>arguments</var> is a single string containing a list
2511of floating point numbers separated by commas or spaces. The number of
2512and meaning of the floating point values depends on the distortion <var>method</var> being used. </p>
2513
2514<p>Choose from these distortion types:</p>
2515
2516<table class="table table-condensed table-striped">
2517 <tr>
2518 <th style="width: 8%">Method</th>
2519 <th>Description</th>
2520 </tr>
2521
2522 <tr>
2523 <td>ScaleRotateTranslate <br> SRT</td>
2524 <td>
2525 Distort image by first scaling and rotating about a given 'center',
2526 before translating that 'center' to the new location, in that order. It
2527 is an alternative method of specifying a 'Affine' type of
2528 distortion, but without shearing effects. It also provides a good way
2529 of rotating and displacing a smaller image for tiling onto a larger
2530 background (IE 2-dimensional animations). <br>
2531
2532 The number of arguments determine the specific meaning of each
2533 argument for the scales, rotation, and translation operations. <br>
2534
2535 <dl class="dl-horizontal">
2536 <dt>2:</dt><dd><var>Scale Angle</var></dd>
2537 <dt>3:</dt><dd><var>X,Y Angle</var></dd>
2538 <dt>4:</dt><dd><var>X,Y Scale Angle</var></dd>
2539 <dt>5:</dt> <dd><var>X,Y ScaleX,ScaleY Angle</var></dd>
2540 <dt>6:</dt> <dd><var>X,Y Scale Angle NewX,NewY</var></dd>
2541 <dt>7:</dt> <dd><var>X,Y ScaleX,ScaleY Angle NewX,NewY</var></dd>
2542 </dl>
2543
2544 This is actually an alternative way of specifying a 2 dimensional linear
2545 'Affine' or 'AffineProjection' distortion. </td> </tr>
2546
2547 <tr>
2548 <td>Affine</td>
2549 <td>
2550 Distort the image linearly by moving a list of at least 3 or more sets
2551 of control points (as defined below). Ideally 3 sets or 12 floating
2552 point values are given allowing the image to be linearly scaled,
2553 rotated, sheared, and translated, according to those three points. See
2554 also the related 'AffineProjection' and 'SRT'
2555 distortions. <br>
2556
2557 More than 3 sets given control point pairs (12 numbers) is least
2558 squares fitted to best match a linear affine distortion. If only 2
2559 control point pairs (8 numbers) are given a two point image translation
2560 rotation and scaling is performed, without any possible shearing,
2561 flipping or changes in aspect ratio to the resulting image. If only one
2562 control point pair is provides the image is only translated, (which may
2563 be a floating point non-integer translation). <br>
2564
2565 This distortion does not include any form of perspective distortion.
2566 </td>
2567
2568 </tr>
2569
2570 <tr>
2571 <td>AffineProjection</td>
2572 <td>
2573 Linearly distort an image using the given Affine Matrix of 6
2574 pre-calculated coefficients forming a set of Affine Equations to map
2575 the source image to the destination image.
2576
2577 <p class="text-center"><var>
2578 s<sub>x</sub>, r<sub>x</sub>,
2579 r<sub>y</sub>, s<sub>y</sub>,
2580 t<sub>x</sub>, t<sub>y</sub>
2581 </var></p>
2582
2583 See <a href="command-line-options.html#affine">-affine</a> setting for more detail, and
2584 meanings of these coefficients. <br>
2585
2586 The distortions 'Affine' and 'SRT' provide
2587 alternative methods of defining this distortion, with ImageMagick doing
2588 the calculations needed to generate the required coefficients. You can
2589 see the internally generated coefficients, by using a <a href="command-line-options.html#verbose">-verbose</a> setting with those other variants. </td>
2590
2591 </tr>
2592
2593 <tr>
2594 <td>BilinearForward<br>
2595 BilinearReverse</td>
2596 <td>
2597 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2598 16 values (see below). Not that lines may not appear straight after
2599 distortion, though the distance between coordinates will remain
2600 consistent. <br>
2601
2602 The 'BilinearForward' is used to map rectangles to any
2603 quadrilateral, while the 'BilinearReverse' form maps any
2604 quadrilateral to a rectangle, while preserving the straight line edges
2605 in each case. <br>
2606
2607 Note that 'BilinearForward' can generate invalid pixels
2608 which will be colored using the <a href="command-line-options.html#mattecolor">-mattecolor</a>
2609 color setting. Also if the quadrilateral becomes 'flipped' the image
2610 may disappear. <br>
2611
2612 There are future plans to produce a true Bilinear distortion that will
2613 attempt to map any quadrilateral to any other quadrilateral, while
2614 preserving edges (and edge distance ratios).
2615
2616 </td>
2617 </tr>
2618
2619 <tr>
2620 <td>Perspective</td>
2621 <td>
2622 Perspective distort the images, using a list of 4 or more sets of
2623 control points (as defined below). More that 4 sets (16 numbers) of
2624 control points provide least squares fitting for more accurate
2625 distortions (for the purposes of image registration and panorama
2626 effects). Less than 4 sets will fall back to a 'Affine'
2627 linear distortion. <br>
2628
2629 Perspective Distorted images ensures that straight lines remain
2630 straight, but the scale of the distorted image will vary. The horizon
2631 is anti-aliased, and the 'sky' color may be set using the
2632 <a href="command-line-options.html#mattecolor">-mattecolor</a> setting. </td>
2633 </tr>
2634
2635 <tr>
2636 <td>PerspectiveProjection </td>
2637 <td>
2638 Do a 'Perspective' distortion biased on a set of 8
2639 pre-calculated coefficients. You can get these coefficients by looking
2640 at the <a href="command-line-options.html#verbose">-verbose</a> output of a
2641 'Perspective' distortion, or by calculating them yourself.
2642 If the last two perspective scaling coefficients are zero, the
2643 remaining 6 represents a transposed 'Affine Matrix'. </td>
2644
2645 </tr>
2646
2647 <tr>
2648 <td>Arc</td>
2649 <td>
2650 Arc the image (variation of polar mapping) over the angle given around
2651 a circle.
2652
2653 <p></p><dl class="dl-horizontal">
2654 <dt>arc_angle</dt>
2655 <dd>The angle over which to arc the image side-to-side</dd>
2656 <dt>rotate_angle</dt>
2657 <dd>Angle to rotate resulting image from vertical center</dd>
2658 <dt>top_radius</dt>
2659 <dd>Set top edge of source image at this radius</dd>
2660 <dt>bottom_radius </dt>
2661 <dd>Set bottom edge to this radius (radial scaling)</dd>
2662 </dl>
2663
2664 The resulting image is always resized to best fit the resulting image,
2665 (as if using <a href="command-line-options.html#distort">+distort</a>) while attempting to
2666 preserve scale and aspect ratio of the original image as much as
2667 possible with the arguments given by the user. All four arguments will
2668 be needed to change the overall aspect ratio of an 'Arc'ed image. <br>
2669
2670 This a variation of a polar distortion designed to try to preserve the
2671 aspect ratio of the image rather than direct Cartesian to Polar
2672 conversion. </td>
2673 </tr>
2674
2675 <tr>
2676 <td>Polar</td>
2677 <td>
2678 Like 'Arc' but do a complete Cartesian to Polar mapping of
2679 the image. that is the height of the input image is mapped to the
2680 radius limits, while the width is wrapped around between the
2681 angle limits. <br>
2682
2683 Arguments: <var>Rmax,Rmin CenterX,CenterY, start,end_angle</var> <br>
2684
2685 All arguments are optional. With <var>Rmin</var> defaulting to zero, the
2686 center to the center of the image, and the angles going from -180 (top)
2687 to +180 (top). If <var>Rmax</var> is given the special value of
2688 '0', the the distance from the center to the nearest edge
2689 is used for the radius of the output image, which will ensure the whole
2690 image is visible (though scaled smaller). However a special value of
2691 '-1' will use the distance from the center to the furthest
2692 corner, This may 'clip' the corners from the input rectangular image,
2693 but will generate the exact reverse of a 'DePolar' with
2694 the same arguments. <br>
2695
2696 If the plus form of distort (<a href="command-line-options.html#distort">+distort</a>) is used
2697 output image center will default to 0,0 of the virtual
2698 canvas, and the image size adjusted to ensure the whole input image is
2699 made visible in the output image on the virtual canvas. </td>
2700
2701 </tr>
2702
2703 <tr>
2704 <td>DePolar</td>
2705 <td>
2706 Uses the same arguments and meanings as a 'Polar' distortion
2707 but generates the reverse Polar to Cartesian distortion. <br>
2708
2709 The special <var>Rmax</var> setting of '0' may however clip
2710 the corners of the input image. However using the special
2711 <var>Rmax</var> setting of '-1' (maximum center to corner
2712 distance) will ensure the whole distorted image is preserved in the
2713 generated result, so that the same argument to 'Polar' will
2714 reverse the distortion re-producing the original.
2715
2716 Note that as this distortion requires the area resampling of a circular
2717 arc, which can not be handled by the builtin EWA resampling function.
2718 As such the normal EWA filters are turned off. It is recommended some
2719 form of 'super-sampling' image processing technique be used to produce
2720 a high quality result. </td>
2721
2722 </tr>
2723
2724 <tr>
2725 <td>Barrel</td>
2726 <td>
2727 Given the four coefficients (A,B,C,D) as defined by <a href="http://wiki.panotools.org/Lens_correction_model">Helmut
2728 Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
2729 correct radial lens distortions. That is in photographs, make straight
2730 lines straight again. <br>
2731
2732 <p class="text-center">Arguments: <var>A B C</var> [ <var>D</var> [
2733 <var>X</var> , <var>Y</var> ] ] <br>
2734 or <var>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2735 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></var>
2736 [ <var>X</var> , <var>Y</var> ] </p>
2737 So that it forms the function
2738 <p class="text-center">Rsrc = r * ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2739 <var>C</var>*r + <var>D</var> )</p>
2740
2741 Where <var>X</var>,<var>Y</var> is the optional center of the distortion
2742 (defaulting to the center of the image). <br>
2743 The second form is typically used to distort images, rather than
2744 correct lens distortions. <br>
2745 </td>
2746
2747 </tr>
2748
2749 <tr>
2750 <td>BarrelInverse</td>
2751 <td>
2752 This is very similar to 'Barrel' with the same set of
2753 arguments, and argument handling. However it uses the inverse
2754 of the radial polynomial,
2755 so that it forms the function
2756 <p class="text-center">Rsrc = r / ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2757 <var>C</var>*r + <var>D</var> )</p>
2758 Note that this is not the reverse of the 'Barrel'
2759 distortion, just a different barrel-like radial distortion method.
2760
2761 </td>
2762 </tr>
2763
2764 <tr>
2765 <td>Shepards</td>
2766 <td>
2767 Distort the given list control points (any number) using an Inverse
2768 Squared Distance Interpolation Method (<a href="http://en.wikipedia.org/wiki/Shepard%27s_method">Shepards
2769 Method</a>). The control points in effect do 'localized' displacement
2770 of the image around the given control point (preserving the look and
2771 the rotation of the area near the control points. For best results
2772 extra control points should be added to 'lock' the positions of the
2773 corners, edges and other unchanging parts of the image, to prevent
2774 their movement. <br>
2775
2776 The distortion has been likened to 'taffy pulling' using nails, or
2777 pins' stuck in a block of 'jelly' which is then moved to the new
2778 position, distorting the surface of the jelly. <br>
2779
2780 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
2781 the <a href="command-line-options.html#sparse-color">-sparse-color</a> method of the same name.
2782
2783 </td>
2784 </tr>
2785
2786</table>
2787
2788<p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
2789distort</a>.</p>
2790
2791<p>Many of the above distortion methods such as '<code>Affine</code>',
2792'<code>Perspective</code>', and '<code>Shepards</code>' use a list control points
2793defining how these points in the given image should be distorted in the
2794destination image. Each set of four floating point values represent a source
2795image coordinate, followed immediately by the destination image coordinate.
2796This produces a list of values such as...</p>
2797<p class="text-center"><var>
2798 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
2799 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
2800 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
2801 ...
2802 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
2803</var></p>
2804<p>where <var>U,V</var> on the source image is mapped to <var>X,Y</var> on the
2805destination image. </p>
2806
2807<p>For example, to warp an image using '<code>perspective</code>' distortion,
2808needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
2809perspective distortion of the built-in "rose:" image. Note how spaces were
2810used to group the 4 sets of coordinate pairs, to make it easier to read and
2811understand.</p>
2812
2813<pre>
2814convert rose: -virtual-pixel black \
2815 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \
2816 rose_3d_rotated.gif"
2817</pre>
2818
2819<p>If more that the required number of coordinate pairs are given for
2820a distortion, the distortion method is 'least squares' fitted to produce the
2821best result for all the coordinate pairs given. If less than the ideal number
2822of points are given, the distort will generally fall back to a simpler form of
2823distortion that can handles the smaller number of coordinates (usually a linear
2824'<code>Affine</code>' distortion). </p>
2825
2826<p>By using more coordinates you can make use of image registration tool to
2827find matching coordinate pairs in overlapping images, so as to improve the
2828'fit' of the distortion. Of course a bad coordinate pair can also make the
2829'fit' worse. Caution is always advised. </p>
2830
2831<p>Colors are acquired from the source image according to a cylindrical
2832resampling <a href="command-line-options.html#filter">-filter</a>, using a special technique known as
2833EWA resampling. This produces very high quality results, especially when
2834images become smaller (minified) in the output, which is very common when
2835using '<code>perspective</code>' distortion. For example here we view
2836a infinitely tiled 'plane' all the way to the horizon. </p>
2837
2838<pre>
2839convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \
2840 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \
2841 checks_tiled.jpg
2842</pre>
2843
2844<p>Note that a infinitely tiled perspective images involving the horizon can
2845be very slow, because of the number of pixels that are compressed to generate
2846each individual pixel close to the 'horizon'. You can turn off EWA
2847resampling, by specifying the special <a href="command-line-options.html#filter">-filter</a> setting of
2848'<code>point</code>' (recommended if you plan to use super-sampling instead).
2849</p>
2850
2851<p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
2852example, <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
2853what these pixels to be visible, set the color to match the rest of the
2854ground. </p>
2855
2856<p>The output image size will by default be the same as the input image. This
2857means that if the part of the distorted image falls outside the viewed area of
2858the 'distorted space', those parts is clipped and lost. However if you use
2859the plus form of the operator (<a href="command-line-options.html#distort">+distort</a>) the operator
2860will attempt (if possible) to show the whole of the distorted image, while
2861retaining a correct 'virtual canvas' offset, for image layering. This offset
2862may need to be removed using <a href="command-line-options.html#repage">+repage</a>, to remove if it
2863is unwanted. </p>
2864
2865<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,
2866and the <a href="command-line-options.html#fx">-fx</a> equivalent to the distortion, for expert study,
2867and debugging purposes. This many not be available for all distorts. </p>
2868
2869<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
2870specify the size and the offset of the generated 'viewport' image of the
2871distorted image space.</p>
2872
2873<p>Setting a "<code><a href="command-line-options.html#define">-define</a>
2874distort:scale={scale_factor}</code>" will scale the output image (viewport or
2875otherwise) by that factor without changing the viewed contents of the
2876distorted image. This can be used either for 'super-sampling' the image for
2877a higher quality result, or for panning and zooming around the image (with
2878appropriate viewport changes, or post-distort cropping and resizing). </p>
2879
2880<p>Setting "<code><a href="command-line-options.html#define">-define</a> resample:verbose=1</code>"
2881will output the cylindrical filter lookup table created by the EWA (Elliptical
2882Weighted Average) resampling algorithm. Note this table uses a squared radius
2883lookup value. This is typically only used for debugging EWA resampling. </p>
2884
2885
2886<div style="margin: auto;">
2887 <h3 class="magick-header"><a id="distribute-cache"></a>-distribute-cache <var>port</var></h3>
2888</div>
2889
2890<p class="magick-description">launch a distributed pixel cache server. </p>
2891
2892<div style="margin: auto;">
2893 <h3 class="magick-header"><a id="dither"></a>-dither <var>method</var></h3>
2894</div>
2895
2896<p class="magick-description">Apply a Riemersma or Floyd-Steinberg error diffusion dither to
2897images when general color reduction is applied via an option, or automagically
2898when saving to specific formats. This enabled by default.</p>
2899
2900<p>Dithering places two or more colors in neighboring pixels so that to the
2901eye a closer approximation of the images original color is reproduced. This
2902reduces the number of colors needed to reproduce the image but at the cost of
2903a lower level pattern of colors. Error diffusion dithers can use any set of
2904colors (generated or user defined) to an image. </p>
2905
2906<p>Dithering is turned on by default, to turn it off use the plus form of the
2907setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
2908without text or graphic aliasing. Disabling dithering often (but not always)
2909leads to faster process, a smaller number of colors, but more cartoon like
2910image coloring. Generally resulting in 'color banding' effects in areas with
2911color gradients. </p>
2912
2913<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
2914color set they created. These operators are also used as part of automatic
2915color reduction when saving images to formats with limited color support, such
2916as <code>GIF:</code>, <code>XBM:</code>, and others, so dithering may also be used
2917in these cases. </p>
2918
2919<p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
2920to generate purely random dither. Or use <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
2921patterns, using uniform color maps, rather than specific color maps. </p>
2922
2923
2924<div style="margin: auto;">
2925 <h3 class="magick-header"><a id="draw"></a>-draw <var>string</var></h3>
2926</div>
2927
2928<p class="magick-description">Annotate an image with one or more graphic primitives.</p>
2929
2930<p>Use this option to annotate or decorate an image with one or more graphic
2931primitives. The primitives include shapes, text, transformations, and pixel
2932operations.</p>
2933
2934<p>The shape primitives:</p>
2935
2936<dl class="dl-horizontal">
2937<dt>point</dt><dd> x,y</dd>
2938<dt>line</dt><dd> x0,y0 x1,y1</dd>
2939<dt>rectangle</dt><dd> x0,y0 x1,y1</dd>
2940<dt>roundRectangle</dt><dd> x0,y0 x1,y1 wc,hc</dd>
2941<dt>arc</dt><dd> x0,y0 x1,y1 a0,a1</dd>
2942<dt>ellipse</dt><dd> x0,y0 rx,ry a0,a1</dd>
2943<dt>circle</dt><dd> x0,y0 x1,y1</dd>
2944<dt>polyline</dt><dd> x0,y0 ... xn,yn</dd>
2945<dt>polygon</dt><dd> x0,y0 ... xn,yn</dd>
2946<dt>bezier</dt><dd> x0,y0 ... xn,yn</dd>
2947<dt>path</dt><dd>specification </dd>
2948<dt>image</dt><dd> operator x0,y0 w,h filename</dd>
2949</dl>
2950
2951<p>The text primitive:</p>
2952
2953<dl class="dl-horizontal">
2954<dt>text</dt><dd>x0,y0 string</dd>
2955</dl>
2956<p>The text gravity primitive:</p>
2957
2958<dl class="dl-horizontal">
2959<dt>gravity</dt><dd>NorthWest, North, NorthEast, West, Center, East, SouthWest, South, or SouthEast</dd>
2960</dl>
2961
2962<p>The text gravity primitive only affects the placement of text and does not
2963interact 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
2964scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
2965
2966<p>The transformation primitives:</p>
2967
2968<dl class="dl-horizontal">
2969<dt>rotate</dt><dd>degrees</dd>
2970<dt>translate</dt><dd>dx,dy</dd>
2971<dt>scale</dt><dd>sx,sy</dd>
2972<dt>skewX</dt><dd>degrees</dd>
2973<dt>skewY</dt><dd>degrees</dd>
2974</dl>
2975
2976<p>The pixel operation primitives:</p>
2977
2978<dl class="dl-horizontal">
2979<dt>color</dt><dd>x0,y0 method</dd>
2980<dt>matte</dt><dd>x0,y0 method</dd>
2981</dl>
2982
2983<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
2984"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>
2985
2986<p>A <code>point</code> primitive is specified by a single <var>point</var> in the
2987pixel plane, that is, by an ordered pair of integer coordinates,
2988<var>x</var>,<var>y</var>. (As it involves only a single pixel, a <code>point</code>
2989primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
2990
2991<p>A <code>line</code> primitive requires a start point and end point.</p>
2992
2993<p>A <code>rectangle</code> primitive is specified by the pair of points at the
2994upper left and lower right corners.</p>
2995
2996<p>A <code>roundRectangle</code> primitive takes the same corner points as
2997a <code>rectangle</code> followed by the width and height of the rounded corners
2998to be removed.</p>
2999
3000<p>The <code>circle</code> primitive makes a disk (filled) or circle (unfilled).
3001Give the center and any point on the perimeter (boundary).</p>
3002
3003<p>The <code>arc</code> primitive is used to inscribe an elliptical segment in
3004to a given rectangle. An <code>arc</code> requires the two corners used for
3005<code>rectangle</code> (see above) followed by the start and end angles of the
3006arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
3007points produced are then joined with a line segment and the resulting segment
3008of an ellipse is filled.</p>
3009
3010<p>Use <code>ellipse</code> to draw a partial (or whole) ellipse. Give the
3011center point, the horizontal and vertical "radii" (the <var>semi-axes</var> of
3012the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
30130,360).</p>
3014
3015<p>The <code>polyline</code> and <code>polygon</code> primitives require three or
3016more points to define their perimeters. A <code>polyline</code> is simply
3017a <code>polygon</code> in which the final point is not stroked to the start
3018point. 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
3019a <code>polyline</code> is identical to a <code>polygon</code>. </p>
3020
3021<p>A <var>coordinate</var> is a pair of integers separated by a space or
3022optional comma. </p>
3023
3024<p>As an example, to define a circle centered at 100,100 that extends to
3025150,150 use:</p>
3026
3027<pre>
3028-draw 'circle 100,100 150,150'
3029</pre>
3030
3031<p>The <code>Bezier</code> primitive creates a spline curve and requires three
3032or points to define its shape. The first and last points are the
3033<var>knots</var> and these points are attained by the curve, while any
3034intermediate coordinates are <var>control points</var>. If two control points
3035are specified, the line between each end knot and its sequentially respective
3036control point determines the tangent direction of the curve at that end. If
3037one control point is specified, the lines from the end knots to the one
3038control point determines the tangent directions of the curve at each end. If
3039more than two control points are specified, then the additional control points
3040act in combination to determine the intermediate shape of the curve. In order
3041to draw complex curves, it is highly recommended either to use the
3042<code>path</code> primitive or to draw multiple four-point bezier segments with
3043the start and end knots of each successive segment repeated. For example:</p>
3044
3045<pre>
3046-draw 'bezier 20,50 45,100 45,0 70,50'
3047-draw 'bezier 70,50 95,100 95,0 120,50'
3048</pre>
3049
3050<p>A <code>path</code> represents an outline of an object, defined in terms of
3051moveto (set a new current point), lineto (draw a straight line), curveto (draw
3052a Bezier curve), arc (elliptical or circular arc) and closepath (close the
3053current shape by drawing a line to the last moveto) elements. Compound paths
3054(i.e., a path with subpaths, each consisting of a single moveto followed by
3055one or more line or curve operations) are possible to allow effects such as
3056<var>donut holes</var> in objects. (See <a href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
3057
3058<p>Use <code>image</code> to composite an image with another image. Follow the
3059image keyword with the composite operator, image location, image size, and
3060filename:</p>
3061
3062<pre>
3063-draw 'image SrcOver 100,100 225,225 image.jpg'
3064</pre>
3065
3066<p>You can use 0,0 for the image size, which means to use the actual
3067dimensions found in the image header. Otherwise, it is scaled to the given
3068dimensions. See <a href="compose.html">Alpha Compositing</a> for
3069a detailed discussion of alpha composition methods that are available. </p>
3070
3071<p>The "special augmented compose operators" such as "dissolve" that require
3072arguments cannot be used at present with the <code>-draw image</code> option.
3073 </p>
3074
3075<p>Use <code>text</code> to annotate an image with text. Follow the text
3076coordinates with a string. If the string has embedded spaces, enclose it in
3077single or double quotes.</p>
3078
3079<p>For example, the following annotates the image with <code>Works like
3080magick!</code> for an image titled <code>bird.miff</code>. </p>
3081
3082<pre>
3083-draw "text 100,100 'Works like magick!' "
3084</pre>
3085
3086<p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
3087to annotate an image with text.</p>
3088
3089<p>The <code>rotate</code> primitive rotates subsequent shape primitives and
3090text 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>
3091option, the origin for transformations is the upper left corner of the
3092region.</p>
3093
3094<p>The <code>translate</code> primitive translates subsequent shape and text
3095primitives.</p>
3096
3097<p>The <code>scale</code> primitive scales them.</p>
3098
3099<p>The <code>skewX</code> and <code>skewY</code> primitives skew them with respect
3100to the origin of the main image or the region.</p>
3101
3102<p>The transformations modify the current affine matrix, which is initialized
3103from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
3104option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
3105option. The initial affine matrix is not affected; that matrix is only changed
3106by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
3107<a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
3108reinitialized from the initial affine matrix.</p>
3109
3110<p>Use the <code>color</code> primitive to change the color of a pixel to the
3111fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
3112a method:</p>
3113
3114<pre>
3115point
3116replace
3117floodfill
3118filltoborder
3119reset
3120</pre>
3121
3122<p>Consider the target pixel as that specified by your coordinate. The
3123<code>point</code> method recolors the target pixel. The <code>replace</code>
3124method recolors any pixel that matches the color of the target pixel.
3125<code>Floodfill</code> recolors any pixel that matches the color of the target
3126pixel and is a neighbor, whereas <code>filltoborder</code> recolors any neighbor
3127pixel that is not the border color. Finally, <code>reset</code> recolors all
3128pixels.</p>
3129
3130<p>Use <code>matte</code> to the change the pixel matte value to transparent.
3131Follow the pixel coordinate with a method (see the <code>color</code> primitive
3132for a description of methods). The <code>point</code> method changes the matte
3133value of the target pixel. The <code>replace</code> method changes the matte
3134value of any pixel that matches the color of the target pixel.
3135<code>Floodfill</code> changes the matte value of any pixel that matches the
3136color of the target pixel and is a neighbor, whereas <code>filltoborder</code>
3137changes 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
3138matte value of all pixels.</p>
3139
3140<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>
3141respectively. Options are processed in command line order so be sure to use
3142these options <var>before</var> the <a href="command-line-options.html#draw">-draw</a> option.</p>
3143
3144<p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
3145than 1.png).</p>
3146
3147<p>Drawing primitives conform to the <a href="magick-vector-graphics.html">Magick
3148Vector Graphics</a> format.</p>
3149
3150
3151<div style="margin: auto;">
3152 <h3 class="magick-header"><a id="duplicate"></a>-duplicate <var>count,indexes</var></h3>
3153</div>
3154
3155<p class="magick-description">duplicate an image one or more times.</p>
3156
3157<p>Specify the count and the image to duplicate by its index in the sequence.
3158The first image is index 0. Negative indexes are relative to the end of the
3159sequence, for example, -1 represents the last image of the sequence. Specify
3160a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g.
31610,2). Use <code>+duplicate</code> to duplicate the last image in the current
3162image sequence.</p>
3163
3164<div style="margin: auto;">
3165 <h3 class="magick-header"><a id="edge"></a>-edge <var>radius</var></h3>
3166</div>
3167
3168<p class="magick-description">detect edges within an image.</p>
3169
3170<div style="margin: auto;">
3171 <h3 class="magick-header"><a id="emboss"></a>-emboss <var>radius</var></h3>
3172</div>
3173
3174<p class="magick-description">emboss an image.</p>
3175
3176<div style="margin: auto;">
3177 <h3 class="magick-header"><a id="encipher"></a>-encipher <var>filename</var></h3>
3178</div>
3179
3180<p class="magick-description">Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</p>
3181
3182<p>Get the passphrase from the file specified by <var>filename</var>.</p>
3183
3184<p>For more information, see the webpage, <a href="http://www.imagemagick.org/www/cipher.html">ImageMagick: Encipher or
3185Decipher an Image</a>.</p>
3186
3187
3188
3189<div style="margin: auto;">
3190 <h3 class="magick-header"><a id="encoding"></a>-encoding <var>type</var></h3>
3191</div>
3192
3193<p class="magick-description">specify the text encoding.</p>
3194
3195<p>Choose from</p>
3196
3197<pre>
3198AdobeCustom AdobeExpert
3199AdobeStandard AppleRoman
3200BIG5 GB2312
3201Latin 2 None
3202SJIScode Symbol
3203Unicode Wansung
3204</pre>
3205
3206<div style="margin: auto;">
3207 <h3 class="magick-header"><a id="endian"></a>-endian <var>type</var></h3>
3208</div>
3209
3210<p class="magick-description">Specify endianness (<code>MSB</code> or <code>LSB</code>) of the image.</p>
3211
3212<p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3213
3214<p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3215
3216
3217<div style="margin: auto;">
3218 <h3 class="magick-header"><a id="enhance"></a>-enhance</h3>
3219</div>
3220
3221<p class="magick-description">Apply a digital filter to enhance a noisy image.</p>
3222
3223
3224<div style="margin: auto;">
3225 <h3 class="magick-header"><a id="equalize"></a>-equalize</h3>
3226</div>
3227
3228<p class="magick-description">perform histogram equalization on the image channel-by-channel.</p>
3229
3230<p>To perform histogram equalization on all channels in concert, transform the
3231image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3232equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3233
3234<p>For example using HSL, we have: ... <code>-colorspace HSL -channel lightness
3235-equalize -colorspace RGB</code> ...</p>
3236
3237<p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3238components transformation that puts most of the information in the first
3239channel. Here we have ... <code>-colorspace OHTA -channel red -equalize
3240-colorspace RGB</code> ...</p>
3241
3242<div style="margin: auto;">
3243 <h3 class="magick-header"><a id="evaluate"></a>-evaluate <var>operator value</var></h3>
3244</div>
3245
3246<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</p>
3247
3248<p>(See the <a href="command-line-options.html#function">-function</a> operator for some
3249multi-parameter functions. See the <a href="command-line-options.html#fx">-fx</a> operator if more
3250elaborate calculations are needed.)</p>
3251
3252<p>The behaviors of each <var>operator</var> are summarized in the
3253following list. For brevity, the numerical value of a "pixel" referred to
3254below is the value of the corresponding channel of that pixel, while
3255a "normalized pixel" is that number divided by the maximum
3256(installation-dependent) value <var>QuantumRange</var>. (If
3257normalized pixels are used, they are restored, following the other
3258calculations, to the full range by multiplying by <var>QuantumRange</var>.)</p>
3259
3260<table class="table table-condensed table-striped">
3261 <col width="25%">
3262 <col width="75%">
3263 <thead>
3264 <tr>
3265 <th><var>operator</var></th>
3266 <th>Summary (see further below for details)</th>
3267 </tr>
3268 </thead>
3269 <tbody>
3270
3271 <tr><td>Abs </td> <td>Add <var>value</var> to pixels and return absolute value. </td></tr>
3272 <tr><td>Add </td> <td>Add <var>value</var> to pixels. </td></tr>
3273 <tr><td>AddModulus </td> <td>Add <var>value</var> to pixels modulo <var>QuantumRange</var>.</td></tr>
3274 <tr><td>And </td> <td>Binary AND of pixels with <var>value</var>.</td></tr>
3275 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3276 <tr><td>Divide </td> <td>Divide pixels by <var>value</var>.</td></tr>
3277 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
3278 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
3279 <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>
3280 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
3281 <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>
3282 <tr><td>Mean </td> <td>Add the <var>value</var> and divide by 2.</td></tr>
3283 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
3284 <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>
3285 <tr><td>Multiply </td> <td>Multiply pixels by <var>value</var>.</td></tr>
3286 <tr><td>Or </td> <td>Binary OR of pixels with <var>value</var>.</td></tr>
3287 <tr><td>Pow </td> <td>Raise normalized pixels to the power <var>value</var>.</td></tr>
3288 <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>
3289 <tr><td>RMS</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3290 <tr><td>RootMeanSquare</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3291 <tr><td>Set </td> <td>Set pixel equal to <var>value</var>.</td></tr>
3292 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3293 <tr><td>Subtract </td> <td>Subtract <var>value</var> from pixels.</td></tr>
3294 <tr><td>Xor </td> <td>Binary XOR of pixels with <var>value.</var></td></tr>
3295
3296 <tr><td> </td><td> </td></tr>
3297
3298 <tr><td>Gaussian-noise</td><td> </td></tr>
3299 <tr><td>Impulse-noise</td><td> </td></tr>
3300 <tr><td>Laplacian-noise</td><td> </td></tr>
3301 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise">-noise</a> operators.)</td></tr>
3302 <tr><td>PoissonNoise</td><td> </td></tr>
3303 <tr><td>Uniform-noise</td><td> </td></tr>
3304
3305 <tr><td> </td><td> </td></tr>
3306
3307 <tr><td>Threshold </td> <td>Threshold pixels larger than <var>value</var>.</td></tr>
3308 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <var>value</var>.</td></tr>
3309 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <var>value</var>. </td></tr>
3310 </tbody>
3311 </table>
3312
3313<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
3314calculations are truncated (clipped) to fit in the interval [0, <var>QuantumRange</var>]. The transparency channel of the image is
3315represented as a 'alpha' values (0 = fully transparent), so, for example, a
3316<code>Divide</code> by 2 of the alpha channel will make the image
3317semi-transparent. Append the percent symbol '<code>%</code>' to specify a value
3318as a percentage of the <var>QuantumRange</var>.</p>
3319
3320<p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3321<a href="command-line-options.html#list">-list evaluate</a>.</p>
3322
3323<p>The results of the <code>Add</code>, <code>Subtract</code> and
3324<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
3325appropriate argument, to linearly modify the overall range of color values.
3326Please note, however, that <a href="command-line-options.html#level">-level</a> treats transparency as
3327'matte' values (0 = opaque), while <a href="command-line-options.html#level">-evaluate</a> works with
3328'alpha' values.</p>
3329
3330<p><code>AddModulus</code> has been added as of ImageMagick 6.4.8-4 and provides
3331addition modulo the <var>QuantumRange</var>. It is therefore
3332equivalent to <code>Add</code> unless the resulting pixel value is outside the
3333interval [0, <var>QuantumRange</var>]. </p>
3334
3335<p><code>Exp or Exponential</code> has been added as of ImageMagick 6.6.5-1 and
3336works on normalized pixel values. The <var>value</var> used with
3337<code>Exp</code> should be negative so as to produce a decaying exponential
3338function. Non-negative values will always produce results larger unity and
3339thus outside the interval [0, <var>QuantumRange</var>]. The
3340formula is expressed below. </p>
3341
3342<p class="text-center">
3343exp(<var>value</var> × <b><var>u</var></b>)
3344</p>
3345
3346<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
3347the result.</p>
3348
3349<p><code>Log</code> has been added as of ImageMagick 6.4.2-1 and works on
3350normalized pixel values. This a <var>scaled</var> log function. The <var>value</var> used with <code>Log</code> provides a <var>scaling
3351factor</var> that adjusts the curvature in the graph of the log function. The
3352formula applied to a normalized value <b><var>u</var></b> is below. </p>
3353
3354<p class="text-center">
3355log(<var>value</var> × <b><var>u</var></b> + 1) / log(<var>value</var> + 1)
3356</p>
3357
3358<p><code>Pow</code> has been added as of ImageMagick 6.4.1-9, and works on
3359normalized 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
3360to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3361with <a href="command-line-options.html#gamma">-gamma</a> is simply the reciprocal of the value used
3362with <code>Pow</code>.</p>
3363
3364<p><code>Cosine</code> and <code>Sine</code> was added as of IM v6.4.8-8 and
3365converts the image values into a value according to a (co)sine wave function.
3366The synonyms <code>Cos</code> and <code>Sin</code> may also be used. The output
3367is biased 50% and normalized by 50% so as to fit in the respective color value
3368range. The <var>value</var> scaling of the <var>period</var> of the
3369function (its frequency), and thus determines the number of 'waves' that will
3370be 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,
3371then the effective period is the <var>half</var> the <var>QuantumRange</var>.</p>
3372
3373<p class="text-center">
33740.5 + 0.5 × cos(2 π <b><var>u</var></b> × <var>value</var>).
3375</p>
3376
3377<p>See also the <a href="command-line-options.html#function">-function</a> operator, which is a
3378multi-value version of evaluate. </p>
3379
3380<div style="margin: auto;">
3381 <h3 class="magick-header"><a id="evaluate-sequence"></a>-evaluate-sequence <var>operator</var></h3>
3382</div>
3383
3384<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or
3385logical expression over a sequence of images.</p>
3386
3387<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>
3388
3389<div style="margin: auto;">
3390 <h3 class="magick-header"><a id="extent"></a>-extent <var>geometry</var></h3>
3391</div>
3392
3393<p class="magick-description">Set the image size and offset.</p>
3394
3395<p>If the image is enlarged, unfilled areas are set to the background color.
3396To position the image, use offsets in the <var>geometry</var>
3397specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting. To
3398specify how to compose the image with the background, use <a href="command-line-options.html#compose">-compose</a>.</p>
3399
3400<p>This command reduces or expands a JPEG image to fit on an 800x600
3401display. If the aspect ratio of the input image isn't exactly 4:3, then the
3402image is centered on an 800x600 black canvas: </p>
3403
3404<pre>
3405convert input.jpg -resize 800x600 -background black -compose Copy \
3406 -gravity center -extent 800x600 -quality 92 output.jpg
3407</pre>
3408
3409<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3410
3411<div style="margin: auto;">
3412 <h3 class="magick-header"><a id="extract"></a>-extract <var>geometry</var></h3>
3413</div>
3414
3415<p class="magick-description">Extract the specified area from image.</p>
3416
3417<p>This option is most useful for extracting a subregion of a very large raw
3418image. Note that these two commands are equivalent:</p>
3419
3420<pre>
3421convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \
3422 image.rgb image.png",
3423convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \
3424 image.rgb image.png"
3425</pre>
3426
3427<p>If you omit the offsets, as in</p>
3428
3429<pre>
3430convert -size 16000x16000 -depth 8 -extract 640x480 \
3431 image.rgb image.png
3432</pre>
3433
3434<p>the image is <var>resized</var> to the specified dimensions instead,
3435equivalent to:</p>
3436
3437<pre>
3438convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png
3439</pre>
3440
3441<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3442
3443<div style="margin: auto;">
3444 <h3 class="magick-header"><a id="family"></a>-family <var>fontFamily</var></h3>
3445</div>
3446
3447<p class="magick-description">Set a font family for text.</p>
3448
3449<p>This setting suggests a font family that ImageMagick should try to use for
3450rendering text. If the family can be found it is used; if not, a default font
3451(e.g., "Arial") or a family known to be similar is substituted (e.g.,
3452"Courier" might be used if "System" is requested but not found). </p>
3453
3454<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>
3455
3456<div style="margin: auto;">
3457 <h3 class="magick-header"><a id="features"></a>-features <var>distance</var></h3>
3458</div>
3459
3460<p class="magick-description">display (co-occurrence 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>
3461
3462<pre>
3463Angular Second Moment Sum Entropy
3464Contrast Entropy
3465Correlation Difference Variance
3466Sum of Squares Variance Difference Entropy
3467Inverse Difference Moment Information Measure of Correlation 1
3468Sum Average Information Measure of Correlation 2
3469Sum Variance Maximum Correlation Coefficient
3470</pre>
3471
3472<div style="margin: auto;">
3473 <h3 class="magick-header"><a id="fft"></a>-fft</h3>
3474</div>
3475
3476<p class="magick-description">implements the forward discrete Fourier transform (DFT).</p>
3477
3478<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3479users in ImageMagick 6.6.0-9). It transforms an image from the normal
3480(spatial) domain to the frequency domain. In the frequency domain, an image is
3481represented as a superposition of complex sinusoidal waves of varying
3482amplitudes. The image x and y coordinates are the possible frequencies along
3483the x and y directions, respectively, and the pixel intensity values are
3484complex numbers that correspond to the sinusoidal wave amplitudes. See for
3485example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3486Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3487Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3488Transform</a>.</p>
3489
3490<p>A single image name is provided as output for this option. However, the
3491output result will have two components. It is either a two-frame image or two
3492separate images, depending upon whether the image format specified supports
3493multi-frame images. The reason that we get a dual output result is because the
3494frequency domain represents an image using complex numbers, which cannot be
3495visualized directly. Therefore, the complex values are automagically separated
3496into a two-component image representation. The first component is the
3497magnitude of the complex number and the second is the phase of the complex
3498number. See for example, <a href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3499
3500<p>The magnitude and phase component images must be specified using image
3501formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3502PFM, EXR and PNG are the recommended image formats to use. All of these
3503formats, except PNG support multi-frame images. So for example,</p>
3504
3505<pre>
3506convert image.png -fft fft_image.miff
3507</pre>
3508
3509<p>generates a magnitude image as <code>fft_image.miff[0]</code> and a phase
3510image as <code>fft_image.miff[1]</code>. Similarly,</p>
3511
3512<pre>
3513convert image.png -fft fft_image.png
3514</pre>
3515
3516<p>generates a magnitude image as <code>fft_image-0.png</code> and a phase image
3517as <code>fft_image-1.png</code>. If you prefer this representation, then you can
3518force 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>
3519
3520<p>The input image can be any size, but if not square and even-dimensioned, it
3521is padded automagically to the larger of the width or height of the input
3522image and to an even number of pixels. The padding will occur at the bottom
3523and/or right sides of the input image. The resulting output magnitude and
3524phase 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>
3525
3526<p>Both output components will have dynamic ranges that fit within
3527[0, <var>QuantumRange</var>], so that HDRI need not be enabled.
3528Phase values nominally range from 0 to 2*π, but is scaled to span the full
3529dynamic range. (The first few releases had non-HDRI scaled but HDRI not
3530scaled). The magnitude image is not scaled and thus generally will contain
3531very small values. As such, the image normally will appear totally black. In
3532order to view any detail, the magnitude image typically is enhanced with a log
3533function into what is usually called the spectrum. A log function is used to
3534enhance the darker values more in comparison to the lighter values. This can
3535be done, for example, as follows:</p>
3536
3537<pre>
3538convert fft_image.miff[0] -contrast-stretch 0 \
3539 -evaluate log 1000 fft_image_spectrum.png"
3540</pre>
3541
3542<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
3543range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3544typically is specified between 100 and 10,000, depending upon the amount of
3545detail that one wants to bring out in the spectrum. Larger values produce more
3546visible detail. Too much detail, however, may hide the important features.</p>
3547
3548<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3549use <a href="command-line-options.html#fft">-fft</a>.</p>
3550
3551<p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3552and imaginary components of the complex valued Fourier transform.</p>
3553
3554<p>However, as the real and imaginary components can contain negative values,
3555this requires that IM be configured with HDRI enabled. In this case, you must
3556use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3557results, since they are formats that preserve both negative and fractional
3558values without clipping them or truncating the fractional part. With either
3559MIFF or TIF, one should add -define quantum:format=32, to allow those image
3560types to work properly in HDRI mode without clipping.</p>
3561
3562<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
3563padding that was discussed above for the magnitude and phase component
3564images.</p>
3565
3566<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
3567about 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>
3568 entry. </p>
3569
3570<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>
3571
3572
3573<div style="margin: auto;">
3574 <h3 class="magick-header"><a id="fill"></a>-fill <var>color</var></h3>
3575</div>
3576
3577<p class="magick-description">color to use when filling a graphic primitive.</p>
3578
3579<p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3580HSL, HSLA, CMYK, or CMYKA specification. See <a href="color.html">Color Names</a> for
3581a description of how to properly specify the color argument.</p>
3582
3583<p>Enclose the color specification in quotation marks to prevent the "#" or
3584the parentheses from being interpreted by your shell.</p>
3585
3586<p>For example,</p>
3587
3588<pre>
3589-fill blue
3590-fill "#ddddff"
3591-fill "rgb(255,255,255)"
3592</pre>
3593
3594<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3595
3596<p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3597
3598<div style="margin: auto;">
3599 <h3 class="magick-header"><a id="filter"></a>-filter <var>type</var></h3>
3600</div>
3601
3602<p class="magick-description">Use this <var>type</var> of filter when resizing or distorting an image.</p>
3603
3604<p>Use this option to affect the resizing operation of an image during
3605operations 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>
3606
3607<pre>
3608Point Hermite Cubic
3609Box Gaussian Catrom
3610Triangle Quadratic Mitchell
3611</pre>
3612
3613<p>The <code>Bessel</code> and <code>Sinc</code> filter is also provided (as well
3614as a faster <code>SincFast</code> equivalent form). However these filters are
3615generally useless on their own as they are infinite filters that are being
3616clipped to the filters support size. Their direct use is not recommended
3617except via expert settings (see below). </p>
3618
3619<p>Instead these special filter functions are typically windowed by a windowing
3620function that the <a href="command-line-options.html#filter">-filter</a> setting defines. That is
3621using these functions will define a 'Windowed' filter, appropriate to the
3622operator involved. Windowed filters include: </p>
3623
3624<pre>
3625Lanczos Hamming Parzen
3626Blackman Kaiser Welsh
3627Hanning Bartlett Bohman
3628</pre>
3629
3630<p>Also one special self-windowing filter is also provided
3631<code>Lagrange</code>, which will automagically re-adjust its function depending
3632on the current 'support' or 'lobes' expert settings (see below).</p>
3633
3634<p>If you do not select a filter with this option, the filter defaults to
3635<code>Mitchell</code> for a colormapped image, an image with a matte channel, or
3636if the image is enlarged. Otherwise the filter default to
3637<code>Lanczos</code>.</p>
3638
3639<p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3640filter</a> option.</p>
3641
3642<p>You can modify how the filter behaves as it scales your image through the
3643use 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>
3644
3645<table class="table table-condensed table-striped">
3646 <tr>
3647 <td>-define filter:blur=<var>factor</var></td>
3648 <td>Scale the X axis of the filter (and its window). Use &gt; 1.0 for
3649 blurry or &lt; 1.0 for sharp. This should only be used with Gaussian and
3650 Gaussian-like filters simple filters, or you may not get the expected
3651 results. </td>
3652 </tr>
3653
3654 <tr>
3655 <td>-define filter:support=<var>radius</var></td>
3656 <td>Set the filter support radius. Defines how large the filter should be and
3657 thus directly defines how slow the filtered resampling process is. All
3658 filters have a default 'preferred' support size. Some filters like
3659 <code>Lagrange</code> and windowed filters adjust themselves depending on
3660 this value. With simple filters this value either does nothing (but slow
3661 the resampling), or will clip the filter function in a detrimental way.
3662 </td>
3663 </tr>
3664
3665 <tr>
3666 <td>-define filter:lobes=<var>count</var></td>
3667 <td>Set the number of lobes to use for the Sinc/Bessel filter. This an
3668 alternative way of specifying the 'support' range of the filter, that is
3669 designed to be more suited to windowed filters, especially when used for
3670 image distorts.</td>
3671 </tr>
3672
3673 <tr>
3674 <td>-define filter:sigma=<var>value</var></td>
3675 <td>The 'sigma' value used to define the <code>Gaussian</code> filter. Default
3676 sigma value is '<code>0.5</code>'. It only effects <code>Gaussian</code> but
3677 does not shrink (but may enlarge) the filter's 'support'. It can be used
3678 to generate very small blurs but without the filter 'missing' pixels due
3679 to using a small support setting. A larger value of '<code>0.707</code>'
3680 (a value of '1/sqrt(2)') is another common setting. </td>
3681 </tr>
3682
3683 <tr>
3684 <td>-define filter:b=<var>b-spline_factor</var></td>
3685 </tr><tr>
3686 <td>-define filter:c=<var>keys_alpha_factor</var></td>
3687 <td>Redefine the values used for cubic filters such as <code>Cubic</code>,
3688 <code>Catrom</code>, <code>Mitchel</code>, and <code>Hermite</code>, as well as
3689 the <code>Parzen</code> cubic windowing function. If only one of the values
3690 are defined, the other is set so as to generate a 'Cubic-Keys' filter.
3691 The values meaning was defined by a research paper by
3692 Mitchell-Netravali.</td>
3693 </tr>
3694
3695 <tr>
3696 <td>-define filter:kaiser-beta=<var>value</var></td>
3697 <td>The 'alpha' value used to as part of the Kaiser Windowing function.
3698 Default value is '6.5'. It only effects Kaiser windowing function, and
3699 does not effect any other attributes.
3700 Before ImageMagick v6.7.6-10, this option was known as "filter:alpha", (an
3701 inheritance from the very old "zoom" program). It was changed to bring the
3702 function in line with more modern academic research usage, and better
3703 assign it be more definitive. </td>
3704 </tr>
3705
3706 <tr>
3707 <td>-define filter:kaiser-alpha=<var>value</var></td>
3708 <td>This value when multiplied by 'PI' is equivalent to "kaiser-beta", and
3709 will override that setting. It only effects Kaiser windowing function,
3710 and does not effect any other attributes. </td>
3711 </tr>
3712
3713 <tr>
3714 <td>-define filter:filter=<var>filter_function</var></td>
3715 <td>Use this function directly as the weighting filter. This will allow
3716 you to directly use a windowing function such as <code>Blackman</code>,
3717 as a resampling filter, rather than as its normal usage as a windowing
3718 function. If defined, no windowing function also defined, the window function is set
3719 to <code>Box</code>). Directly specifying <code>Sinc</code> or <code>Jinc</code>
3720 as a filter will also do this. </td>
3721 </tr>
3722
3723 <tr>
3724 <td>-define filter:window=<var>filter_function</var></td>
3725 <td>The IIR (infinite impulse response) filters <code>Sinc</code> and
3726 <code>Jinc</code> are windowed (brought down to zero over the defined
3727 support range) with the given filter. This allows you to specify a filter
3728 function to be used as a windowing function for these IIR filters.
3729 Many of the defined filters are actually windowing functions for these IIR
3730 filters. A typical choices is <code>Box</code>, (which effectively turns
3731 off the windowing function). </td>
3732 </tr>
3733
3734 <tr>
3735 <td>-define filter:win-support=<var>radius</var></td>
3736 <td>Scale windowing function to this size instead. This causes the windowing
3737 (or self-windowing Lagrange filter) to act is if the support window is
3738 larger than what is actually supplied to the calling operator. The filter
3739 however is still clipped to the real support size given. If unset this
3740 will equal the normal filter support size. </td>
3741 </tr>
3742
3743 <tr>
3744 <td>-define filter:verbose=<var>1</var></td>
3745 <td>This causes IM to print information on the final internal filter
3746 selection to standard output. This includes a commented header on the
3747 filter settings being used, and data allowing the filter weights to be
3748 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
3749 a <code>SincFast</code> windowed <code>SincFast</code> filter, while
3750 <code>Mitchell</code> is defined as a general <code>Cubic</code> family filter
3751 with specific 'B' and 'C' settings. </td>
3752 </tr>
3753
3754</table>
3755
3756<p>For example, to get a 8 lobe jinc windowed sinc filter (Genseng filter?):</p>
3757
3758<pre>
3759convert image.png \
3760 -filter sinc \
3761 -set filter:window=jinc \
3762 -set filter:lobes=8 \
3763 -resize 150% image.jpg"
3764</pre>
3765
3766<p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
3767
3768<pre>
3769convert image.png \
3770 -set filter:filter=sinc \
3771 -set filter:lobes=4 \
3772 -resize 150% image.jpg"
3773</pre>
3774
3775<p>To extract the data for a raw windowing function, combine it with
3776a '<code>Box</code>' filter. For example the '<code>Welch</code> parabolic
3777windowing function. </p>
3778
3779<pre>
3780convert null: -define filter:filter=Box \
3781 -define filter:window=Welch \
3782 -define filter:support=1.0 \
3783 -define filter:verbose=1 \
3784 -resize 2 null: &gt; window_welch.dat
3785gnuplot
3786 set grid
3787 plot \"window_welch.dat\" with lines
3788</pre>
3789
3790<p>Note that the use of expert options is provided for image processing experts
3791who have studied and understand how resize filters work. Without this
3792knowledge, and an understanding of the definition of the actual filters
3793involved, using expert settings are more likely to be detrimental to your image
3794resizing.</p>
3795
3796
3797<div style="margin: auto;">
3798 <h3 class="magick-header"><a id="flatten"></a>-flatten</h3>
3799</div>
3800
3801<p class="magick-description">This is a simple alias for the <a href="command-line-options.html#layers">-layers</a> method "flatten".</p>
3802
3803
3804<div style="margin: auto;">
3805 <h3 class="magick-header"><a id="flip"></a>-flip</h3>
3806</div>
3807
3808<p class="magick-description">create a <var>mirror image</var></p>
3809
3810<p>reflect the scanlines in the vertical direction. The image will be mirrored
3811upside-down. </p>
3812
3813
3814<div style="margin: auto;">
3815 <h3 class="magick-header"><a id="floodfill"></a>-floodfill {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var> <var>color</var></h3>
3816</div>
3817
3818<p class="magick-description">floodfill the image with color at the specified offset.</p>
3819
3820<p>Flood fill starts from the given 'seed point' which is not gravity effected.
3821Any color that matches within <a href="command-line-options.html#fuzz">-fuzz</a> color distance of the
3822given <var>color</var> argument, connected to that 'seed point'
3823will be replaced with the current <a href="command-line-options.html#fill">-fill</a> color. </p>
3824
3825<p>Note that if the pixel at the 'seed point' does not itself match the given
3826<var>color</var> (according to <a href="command-line-options.html#fuzz">-fuzz</a>), then no
3827action will be taken. </p>
3828
3829<p>This operator works more like the <a href="command-line-options.html#opaque">-opaque</a> option, than
3830a more general flood fill that reads the matching color directly at the 'seed
3831point'. For this form of flood fill, look at <a href="command-line-options.html#draw">-draw</a> and
3832its 'color floodfill' drawing method. </p>
3833
3834
3835<div style="margin: auto;">
3836 <h3 class="magick-header"><a id="flop"></a>-flop</h3>
3837</div>
3838
3839<p class="magick-description">create a <var>mirror image</var>.</p>
3840
3841<p>Reflect the scanlines in the horizontal direction, just like the image in
3842a vertical mirror. </p>
3843
3844
3845<div style="margin: auto;">
3846 <h3 class="magick-header"><a id="font"></a>-font <var>name</var></h3>
3847</div>
3848
3849<p class="magick-description">set the font to use when annotating images with text, or creating labels.</p>
3850
3851<p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
3852option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
3853
3854<p>In addition to the fonts specified by the above pre-defined list, you can
3855also specify a font from a specific source. For example <code>Arial.ttf</code>
3856is a TrueType font file, <code>ps:helvetica</code> is PostScript font, and
3857<code>x:fixed</code> is X11 font.</p>
3858
3859<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>
3860
3861
3862<div style="margin: auto;">
3863 <h3 class="magick-header"><a id="foreground"></a>-foreground <var>color</var></h3>
3864</div>
3865
3866<p class="magick-description">Define the foreground color for menus.", "display</p>
3867
3868<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
3869
3870<p>The default foreground color is black.</p>
3871
3872<div style="margin: auto;">
3873 <h3 class="magick-header"><a id="format"></a>-format <var>type</var></h3>
3874</div>
3875
3876<p class="magick-description">the image format type.</p>
3877
3878<p>When used with the <code>mogrify</code> utility, this option converts any
3879image to the image <a href="formats.html">format</a> you specify.
3880For a list of image format types supported by ImageMagick, use <a href="command-line-options.html#list">-list format</a>.</p>
3881
3882<p>By default the file is written to its original name. However, if the
3883filename extension matches a supported format, the extension is replaced with
3884the image format type specified with <a href="command-line-options.html#format">-format</a>. For
3885example, if you specify <var>tiff</var> as the format type and the
3886input image filename is <var>image.gif</var>, the output image
3887filename becomes <var>image.tiff</var>.</p>
3888
3889<div style="margin: auto;">
3890 <h3 class="magick-header"><a id="format_identify_"></a>-format <var>string</var></h3>
3891</div>
3892
3893<p class="magick-description">output formatted image characteristics.</p>
3894
3895<p>See <a href="escape.html">Format and Print Image
3896Properties</a> for an explanation on how to specify the argument to this
3897option.</p>
3898
3899<div style="margin: auto;">
3900 <h3 class="magick-header"><a id="frame"></a>-frame <var>geometry</var></h3>
3901</div>
3902
3903<p class="magick-description">Surround the image with a border or beveled frame.</p>
3904
3905<p>The color of the border is specified with the <a href="command-line-options.html#mattecolor">-mattecolor</a> command line option. </p>
3906
3907<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
3908height that is added to the dimensions of the image. If no offsets are given
3909in the <var>geometry</var> argument, then the border added is
3910a solid color. Offsets <var>x</var> and <var>y</var>, if present, specify that
3911the width and height of the border is partitioned to form an outer bevel of
3912thickness <var>x</var> pixels and an inner bevel of thickness
3913<var>y</var> pixels. Negative offsets make no sense as frame arguments.
3914</p>
3915
3916<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
3917'<code>Over</code>' composition method. It generates an image of the appropriate
3918size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
3919draws 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
3920center of this image. This means that with the default compose method of
3921'<code>Over</code>' any transparent parts may be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
3922
3923<p>The image composition is not
3924affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
3925
3926
3927<div style="margin: auto;">
3928 <h3 class="magick-header"><a id="frame_import_"></a>-frame</h3>
3929</div>
3930
3931<p class="magick-description">include the X window frame in the imported image. </p>
3932<div style="margin: auto;">
3933 <h3 class="magick-header"><a id="function"></a>-function <var>function</var> <var>parameters</var></h3>
3934</div>
3935
3936<p class="magick-description">Apply a function to channel values.</p>
3937
3938<p>This operator performs calculations based on the given arguments to modify
3939each 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
3940calculations are handled.</p>
3941
3942<p>This is can be considered a multi-argument version of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
3943ImageMagick 6.4.8−8.)</p>
3944
3945<p>Here, <var>parameters</var> is a comma-separated list of
3946numerical values. The number of values varies depending on which <var>function</var> is selected. Choose the <var>function</var> from:</p>
3947
3948<pre>
3949Polynomial
3950Sinusoid
3951Arcsin
3952Arctan
3953</pre>
3954
3955<p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
3956use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
3957
3958<dl class="dl-horizontal">
3959 <dt>Polynomial</dt>
3960 <dd><p>The <code>Polynomial</code> function takes an arbitrary number of parameters,
3961these being the coefficients of a polynomial, in decreasing order of degree.
3962That is, entering</p>
3963
3964<pre>
3965-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>
3966</pre>
3967
3968<p>will invoke a polynomial function given by</p>
3969
3970<pre>
3971<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>,
3972</pre>
3973
3974<p>where <b><var>u</var></b> is pixel's original normalized channel value.</p>
3975
3976<p>The <code>Polynomial</code> function can be used in place of <code>Set</code>
3977(the <var>constant</var> polynomial) and <code>Add</code>, <code>Divide</code>,
3978<code>Multiply</code>, and <code>Subtract</code> (some <var>linear</var>
3979polynomials) 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
3980correspondences follow.</p>
3981
3982<table class="table table-condensed table-striped">
3983 <tr>
3984 <td>-evaluate Set <var>value</var> </td>
3985 <td>-function Polynomial <var>value</var></td>
3986 <td>(Constant functions; set <var>value</var>×100% gray when channels are RGB.)</td>
3987 </tr>
3988 <tr>
3989 <td>-evaluate Add <var>value</var> </td>
3990 <td>-function Polynomial 1,<var>value</var></td>
3991 </tr>
3992 <tr>
3993 <td>-evaluate Subtract <var>value</var> </td>
3994 <td>-function Polynomial 1,−<var>value</var></td>
3995 </tr>
3996 <tr>
3997 <td>-evaluate Multiply <var>value</var> </td>
3998 <td>-function Polynomial <var>value</var>,0</td>
3999 </tr>
4000 <tr>
4001 <td>+level black% x white%</td>
4002 <td>-function Polynomial A,B</td>
4003 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
4004 </tr>
4005</table>
4006
4007<p>The <code>Polynomial</code> function gives great versatility, since
4008polynomials can be used to fit any continuous curve to any degree of accuracy
4009desired.</p>
4010
4011</dd>
4012<dt>Sinusoid</dt>
4013<dd>
4014<p>The <code>Sinusoid</code> function can be used to vary the channel values
4015sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
4016values are given as one to four parameters, as follows,</p>
4017
4018<pre>
4019-function <code>Sinusoid</code> <var>freq</var>,[<var>phase</var>,[<var>amp</var>,[<var>bias</var>]]]
4020</pre>
4021
4022<p>where <var>phase</var> is in degrees. (The domain [0,1] of the function
4023corresponds to 0 through <var>freq</var>×360 degrees.)
4024The result is that if a pixel's normalized channel value is originally
4025<b><var>u</var></b>, its resulting normalized value is given by </p>
4026
4027<pre>
4028<var>amp</var> * sin(2*π* (<var>freq</var> * <b><var>u</var></b> + <var>phase</var> / 360)) + <var>bias</var>
4029</pre>
4030
4031<p> For example, the following generates a curve that starts and ends at 0.9
4032(when <b><var>u</var></b>=0 and 1, resp.), oscillating three times between
4033.7−.2=.5 and .7+.2=.9. </p>
4034
4035<pre>
4036-function Sinusoid 3,-90,.2,.7
4037</pre>
4038
4039<p>The default values of <var>amp</var> and <var>bias</var> are both .5. The default for <var>phase</var>
4040is 0.</p>
4041
4042<p>The <code>Sinusoid</code> function generalizes <code>Sin</code> and
4043<code>Cos</code> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
4044varying amplitude, phase and bias. The correspondence is as follows.</p>
4045
4046<table class="table table-condensed table-striped">
4047 <tr>
4048 <td>-evaluate Sin <var>freq</var> </td>
4049 <td>-function Sinusoid <var>freq</var>,0 </td>
4050 </tr>
4051 <tr>
4052 <td>-evaluate Cos <var>freq</var> </td>
4053 <td>-function Sinusoid <var>freq</var>,90 </td>
4054 </tr>
4055</table>
4056 </dd>
4057<dt>ArcSin</dt>
4058<dd>
4059<p>The <code>ArcSin</code> function generates the inverse curve of a Sinusoid,
4060and can be used to generate cylindrical distortion and displacement maps.
4061The curve can be adjusted relative to both the input values and output range
4062of values.</p>
4063
4064<pre>
4065-function <code>ArcSin</code> <var>width</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4066</pre>
4067
4068<p>with all values given in terms of normalized color values (0.0 for black,
40691.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
4070for bout input (<var>width</var>), and output (<var>width</var>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
4071
4072<pre>
4073<var>range</var>/π * asin( 2/<var>width</var> * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4074</pre>
4075
4076</dd>
4077<dt>ArcTan</dt>
4078<dd>
4079<p>The <code>ArcTan</code> function generates a curve that smooth crosses from
4080limit values at infinities, though a center using the given slope value.
4081All these values can be adjusted via the arguments.</p>
4082
4083<pre>
4084-function <code>ArcTan</code> <var>slope</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
4085</pre>
4086
4087<p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
4088</p>
4089
4090<pre>
4091<var>range</var>/π * atan( <var>slope</var>*π * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
4092</pre>
4093 </dd>
4094
4095</dl>
4096
4097
4098
4099<div style="margin: auto;">
4100 <h3 class="magick-header"><a id="fuzz"></a>-fuzz <var>distance</var>{<var>%</var>}</h3>
4101</div>
4102
4103<p class="magick-description">Colors within this <var>distance</var> are considered equal.</p>
4104
4105<p>A number of algorithms search for a target color. By default the color must
4106be exact. Use this option to match colors that are close to the target color
4107in RGB space. For example, if you want to automagically trim the edges of an
4108image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
4109background color may differ by a small amount. This option can account for
4110these differences.</p>
4111
4112<p>The <var>distance</var> can be in absolute intensity units or, by
4113appending <code>%</code> as a percentage of the maximum possible intensity (255,
411465535, or 4294967295).</p>
4115
4116<p>Use <a href="command-line-options.html#fuzz">+fuzz</a> to reset the fuzz value to 0.</p>
4117
4118
4119<div style="margin: auto;">
4120 <h3 class="magick-header"><a id="fx"></a>-fx <var>expression</var></h3>
4121</div>
4122
4123<p class="magick-description">apply a mathematical expression to an image or image channels.</p>
4124
4125<p>If the first character of <var>expression</var> is <code>@</code>,
4126the expression is read from a file titled by the remaining characters in the
4127string.</p>
4128
4129<p>See <a href="fx.html">FX,
4130The Special Effects Image Operator</a> for a detailed discussion of this
4131option.</p>
4132
4133
4134<div style="margin: auto;">
4135 <h3 class="magick-header"><a id="gamma"></a>-gamma <var>value</var></h3>
4136</div>
4137
4138<p class="magick-description">level of gamma correction.</p>
4139
4140<p>The same color image displayed on two different workstations may look
4141different due to differences in the display monitor. Use gamma correction to
4142adjust for this color difference. Reasonable values extend from
4143<code>0.8</code> to <code>2.3</code>. Gamma less than 1.0 darkens the image and
4144gamma greater than 1.0 lightens it. Large adjustments to image gamma may
4145result in the loss of some image information if the pixel quantum size is only
4146eight bits (quantum range 0 to 255).</p>
4147
4148<p>Gamma adjusts the image's channel values pixel-by-pixel according to
4149a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
4150normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
4151same as taking the square root of the image.</p>
4152
4153<p>You can apply separate gamma values to the red, green, and blue channels of
4154the image with a gamma value list delimited with commas (e.g.,
4155<code>1.7,2.3,1.2</code>).</p>
4156
4157<p>Use <a href="command-line-options.html#gamma">+gamma <var>value</var></a> to set the
4158image gamma level without actually adjusting the image pixels. This option
4159is useful if the image is of a known gamma but not set as an image attribute
4160(e.g. PNG images). Write the "file gamma" which is the reciprocal of the
4161display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
4162chunk, use</p>
4163
4164<pre>
4165convert input.png +gamma .45455 output.png
4166</pre>
4167
4168<p>(0.45455 is 1/2.2)</p>
4169
4170<p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
4171
4172<div style="margin: auto;">
4173 <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>
4174</div>
4175
4176<p class="magick-description">Blur the image with a Gaussian operator.</p>
4177
4178<p>Convolve the image with a Gaussian or normal distribution using the given
4179<var>Sigma</var> value. The formula is:</p>
4180
4181<p class="text-center"><img class="img-thumbnail" alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"> </p>
4182
4183<p>The <var>Sigma</var> value is the important argument, and
4184determines the actual amount of blurring that will take place. </p>
4185
4186<p>The <var>Radius</var> is only used to determine the size of the
4187array which will hold the calculated Gaussian distribution. It should be an
4188integer. If not given, or set to zero, IM will calculate the largest possible
4189radius that will provide meaningful results for the Gaussian distribution.
4190</p>
4191
4192<p>The larger the <var>Radius</var> the radius the slower the
4193operation is. However too small a <var>Radius</var>, and sever
4194aliasing effects may result. As a guideline, <var>Radius</var>
4195should be at least twice the <var>Sigma</var> value, though three
4196times will produce a more accurate result. </p>
4197
4198<p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4199full 2-dimensional convolution is used to generate the weighted average of the
4200neighboring pixels. </p>
4201
4202<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4203pixels which are outside the image proper are blurred into the final result.
4204</p>
4205
4206
4207<div style="margin: auto;">
4208 <h3 class="magick-header"><a id="geometry"></a>-geometry <var>geometry</var></h3>
4209</div>
4210
4211<p class="magick-description">Set the preferred size and location of the image.</p>
4212
4213<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4214
4215<div style="margin: auto;">
4216 <h3 class="magick-header"><a id="gravity"></a>-gravity <var>type</var></h3>
4217</div>
4218
4219<p class="magick-description">Sets the current gravity suggestion for various other settings and options.</p>
4220
4221<p>Choices include: <code>NorthWest</code>, <code>North</code>,
4222<code>NorthEast</code>, <code>West</code>, <code>Center</code>, <code>East</code>,
4223<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
4224installation.</p>
4225
4226<p>The direction you choose specifies where to position text or subimages. For
4227example, a gravity of <code>Center</code> forces the text to be centered within
4228the 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
4229text 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>
4230
4231<p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4232<a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4233take <var>geometry</var> as an argument, such as the <a href="command-line-options.html#crop">-crop</a> option. </p>
4234
4235<p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4236or setting having a <var>geometry</var> argument that specifies an
4237offset, the offset is usually applied to the point within the image suggested
4238by the <a href="command-line-options.html#gravity">-gravity</a> argument. Thus, in the following
4239command, for example, suppose the file <code>image.png</code> has dimensions
4240200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4241is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4242<code>Center</code>, which suggests the midpoint of the image, at the point
4243(100,50). The offset (−40,20) is applied to that point, giving
4244(100−40,50+20)=(60,70), so the specified 10x10 region is located at
4245that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4246region itself, which is <var>centered</var> at the pixel
4247coordinate (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>
4248
4249<pre>
4250convert image.png -gravity Center -region 10x10-40+20 \
4251 -negate output.png
4252</pre>
4253
4254<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
4255within the composite.</p>
4256
4257<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
4258within a tile. The default gravity is <code>Center</code> for this purpose.</p>
4259
4260
4261<div style="margin: auto;">
4262 <h3 class="magick-header"><a id="grayscale"></a>-grayscale <var>method</var></h3>
4263</div>
4264
4265<p class="magick-description">convert image to grayscale.</p>
4266
4267<p>This will use one of the <a href="command-line-options.html#intensity">-intensity</a> methods to
4268convert the given image into a linear-grayscale image. </p>
4269
4270<p>For example, to convert an image to (linear) Rec709Luminance grayscale, type:</p>
4271
4272<pre>
4273convert in.png -grayscale Rec709Luminance out.png
4274</pre>
4275
4276<p>which is equivalent to:</p>
4277
4278<pre>
4279convert in.png -colorspace gray out.png
4280</pre>
4281
4282<p>Similarly, to convert an image to (non-linear) Rec709Luma grayscale, type:</p>
4283
4284<pre>
4285convert in.png -grayscale Rec709Luma out.png
4286</pre>
4287
4288<p>which is equivalent to:</p>
4289
4290<pre>
4291convert in.png -set colorspace RGB -colorspace gray out.png
4292</pre>
4293
4294<p>Note that a 'colorspace' intensity method will produce the same result
4295regardless of the current colorpsace of the image. But a 'mathematical'
4296intensity method will depend on the current colorspace the image is currently
4297using. </p>
4298
4299<p>While this operation uses an <a href="command-line-options.html#intensity">-intensity</a> method,
4300it does not use or set the <a href="command-line-options.html#intensity">-intensity</a> setting, so
4301will not effect other operations that may use that setting.</p>
4302
4303
4304<div style="margin: auto;">
4305 <h3 class="magick-header"><a id="green-primary"></a>-green-primary <var>x,y</var></h3>
4306</div>
4307
4308<p class="magick-description">green chromaticity primary point.</p>
4309
4310
4311<div style="margin: auto;">
4312 <h3 class="magick-header"><a id="hald-clut"></a>-hald-clut</h3>
4313</div>
4314
4315<p class="magick-description">apply a Hald color lookup table to the image.</p>
4316
4317<p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4318dimensions. Create it with the <code>HALD:</code> prefix (e.g. HALD:8). You
4319can apply any color transformation to the Hald image and then use this option
4320to apply the transform to the image. </p>
4321
4322<pre>
4323convert image.png hald.png -hald-clut transform.png
4324</pre>
4325
4326<p>This option provides a convenient method for you to use Gimp or Photoshop
4327to make color corrections to the Hald CLUT image and subsequently apply them
4328to multiple images using an ImageMagick script. </p>
4329
4330<p>Note that the representation is only of the normal RGB color space and that
4331the whole color value triplet is used for the interpolated lookup of the
4332represented 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
4333images transparency or alpha/matte channel.</p>
4334
4335<p>See also <a href="command-line-options.html#clut">-clut</a> which provides color value replacement
4336of the individual color channels, usually involving a simpler gray-scale
4337image. E.g: gray-scale to color replacement, or modification by a histogram
4338mapping. </p>
4339
4340
4341<div style="margin: auto;">
4342 <h3 class="magick-header"><a id="help"></a>-help</h3>
4343</div>
4344
4345<p class="magick-description">print usage instructions.</p>
4346
4347<div style="margin: auto;">
4348 <h3 class="magick-header"><a id="highlight-color"></a>-highlight-color <var>color</var></h3>
4349</div>
4350
4351<p class="magick-description">when comparing images, emphasize pixel differences with this color.</p>
4352
4353<div style="margin: auto;">
4354 <h3 class="magick-header"><a id="hough-lines"></a>-hough-lines <var>width</var>x<var>height</var>{<var>+threshold</var>}</h3>
4355</div>
4356
4357<p class="magick-description">identify straight lines in the image (e.g. -hough-lines 9x9+195).</p>
4358
4359<p>Use the Hough line detector with any binary edge extracted image to locate and draw any straight lines that it finds.</p>
4360
4361<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>.
4362
4363<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>
4364
4365<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>
4366
4367<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>
4368
4369<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>
4370
4371<p>A text file listing the endpoints and counts may be created by using the suffix, .mvg, for the output image.</p>
4372
4373<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>
4374
4375<div style="margin: auto;">
4376 <h3 class="magick-header"><a id="iconGeometry"></a>-iconGeometry <var>geometry</var></h3>
4377</div>
4378
4379<p class="magick-description">specify the icon geometry.</p>
4380
4381<p>Offsets, if present in the geometry specification, are handled in the same
4382manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4383handle negative offsets.</p>
4384
4385<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4386
4387<div style="margin: auto;">
4388 <h3 class="magick-header"><a id="iconic"></a>-iconic</h3>
4389</div>
4390
4391<p class="magick-description">start in icon mode in X Windows", 'animate', 'display</p>
4392
4393<div style="margin: auto;">
4394 <h3 class="magick-header"><a id="identify"></a>-identify</h3>
4395</div>
4396
4397<p class="magick-description">identify the format and characteristics of the image.</p>
4398
4399<p>This information is printed: image scene number; image name; image size;
4400the image class (<var>DirectClass</var> or <var>PseudoClass</var>); the total number of unique colors; and the
4401number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4402a description of the image class.</p>
4403
4404<p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4405in the image and color reduction error values are printed. Refer to <a href="quantize.html">color
4406reduction algorithm</a> for a description of these values.</p>
4407
4408<p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4409amounts of image properties are displayed including image statistics, profiles,
4410image histogram, and others.</p>
4411
4412<div style="margin: auto;">
4413 <h3 class="magick-header"><a id="ift"></a>-ift</h3>
4414</div>
4415
4416<p class="magick-description">implements the inverse discrete Fourier transform (DFT).</p>
4417
4418<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4419users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4420images from the frequency domain to a single image in the normal or spatial
4421domain. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4422<a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4423<a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4424
4425<p>For example, depending upon the image format used to store the result of
4426the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4427
4428<pre>
4429convert fft_image.miff -ift fft_image_ift.png
4430</pre>
4431
4432<p>or</p>
4433
4434<pre>
4435convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png
4436</pre>
4437
4438<p>The resulting image may need to be cropped due to padding introduced when
4439the 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
4440the right and/or bottom sides of the image.</p>
4441
4442<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4443use <a href="command-line-options.html#ift">-ift</a>.</p>
4444
4445<p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4446and imaginary images from the frequency domain to a single image in the normal
4447(spatial) domain.</p>
4448
4449<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>
4450
4451<div style="margin: auto;">
4452 <h3 class="magick-header"><a id="immutable"></a>-immutable</h3>
4453</div>
4454
4455<p class="magick-description">make image immutable.</p>
4456
4457<div style="margin: auto;">
4458 <h3 class="magick-header"><a id="implode"></a>-implode <var>factor</var></h3>
4459</div>
4460
4461<p class="magick-description">implode image pixels about the center.</p>
4462
4463<div style="margin: auto;">
4464 <h3 class="magick-header"><a id="insert"></a>-insert <var>index</var></h3>
4465</div>
4466
4467<p class="magick-description">insert the last image into the image sequence.</p>
4468
4469<p>This option takes last image in the current image sequence and inserts it
4470at the given index. If a negative index is used, the insert position is
4471calculated before the last image is removed from the sequence. As such
4472<code>-insert -1</code> will result in no change to the image sequence.</p>
4473
4474<p>The <code>+insert</code> option is equivalent to <code>-insert -1</code>. In
4475other words, insert the last image, at the end of the current image sequence.
4476Consequently this has no effect on the image sequence order.</p>
4477
4478<div style="margin: auto;">
4479 <h3 class="magick-header"><a id="intensity"></a>-intensity <var>method</var></h3>
4480</div>
4481
4482<p class="magick-description">method to generate intensity value from pixel.</p>
4483
4484<p>ImageMagick provides a number of methods used in situations where an
4485operator needs to determine a single grayscale value for some purpose, from
4486an image with red, green, and blue pixel components. Typically the linear
4487<code>Rec709Luminance</code> formula is used, which is the same formula used when
4488converting images to <code>-colorspace gray</code>. </p>
4489
4490<p>The following formulas are currently provided, and will first convert
4491the pixel values to linear-RGB or non-linear sRGB colorspace before
4492being applied to calculate the final greyscale value. </p>
4493
4494<dl class="dl-horizontal">
4495<dt>Rec601Luma</dt><dd> 0.298839R' + 0.586811G'+ 0.114350B'</dd>
4496<dt>Rec601Luminance</dt><dd> 0.298839R + 0.586811G + 0.114350B</dd>
4497<dt>Rec709Luma</dt><dd> 0.212656R' + 0.715158G' + 0.072186B'</dd>
4498<dt>Rec709Luminance</dt><dd> 0.212656R + 0.715158G + 0.072186B</dd>
4499<dt>Brightness</dt><dd> max(R', G', B')</dd>
4500<dt>Lightness</dt><dd> (min(R', G', B') + max(R', G', B')) / 2.0</dd>
4501</dl>
4502
4503<p>Note that the above R,G,B values is the image's linear-RGB values, while
4504R',G',B' are sRGB non-linear values. </p>
4505
4506<p>These intensity methods are mathematical in nature and will use the
4507current value in the images respective R,G,B channel regardless of
4508what that is, or what colorspace the image is currently using.</p>
4509
4510<dl class="dl-horizontal">
4511<dt>Average</dt><dd>(R + G + B) / 3.0</dd>
4512<dt>MS</dt><dd>(R^2 + G^2 + B^2) / 3.0</dd>
4513<dt>RMS</dt><dd>sqrt( (R^2 + G^2 + B^2) / 3.0 )</dd>
4514</dl>
4515
4516<p>These methods are often used for other purposes, such as generating a
4517grayscale difference image between two color images (using <a href="command-line-options.html#compose">-compose</a> '<code>Difference</code>' composition. </p>
4518
4519<p> For example The 'MS' (Mean Squared) setting is good for minimizing color
4520error comparisions. While... The method 'RMS' (Root Mean Squared) for
4521example is appropriate for calculating color vector distance, from a color
4522difference 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>
4523
4524<p>See also <a href="command-line-options.html#grayscale">-grayscale</a> which applies one of the above
4525grayscaling formula directly to an image without setting the <a href="command-line-options.html#intensity">-intensity</a> setting.</p>
4526
4527<p>The <a href="command-line-options.html#colorspace">-colorspace gray</a> image conversion also uses
4528the current intensity setting, but will always convert the image to the
4529appropriate sRGB or linear-RGB colorspace before appling the above
4530function.</p>
4531
4532<p>To print a complete list of possible pixel intensity setting methods, use <a href="command-line-options.html#list">-list intensity</a>.</p>
4533
4534<p>Operators affected by the <a href="command-line-options.html#intensity">-intensity</a> setting include:</p>
4535
4536<pre>
4537-adaptive-blur
4538-adaptive-sharpen
4539-black-threshold
4540-clut (when mapping greyscale CLUT image to alpha channel if set by -channels)
4541-colors for gray colorspace
4542-compose {LightenIntensity, DarkenIntensity, CopyOpacity, CopyBlack}
4543-contrast-stretch
4544-distort {ErodeIntensity, DilateIntensity}
4545-normalize
4546-random-threshold
4547-selective-blur
4548-shade
4549-threshold
4550-tint
4551-white-threshold
4552</pre>
4553
4554<div style="margin: auto;">
4555 <h3 class="magick-header"><a id="intent"></a>-intent <var>type</var></h3>
4556</div>
4557
4558<p class="magick-description">use this type of rendering intent when managing the image color.</p>
4559
4560<p>Use this option to affect the color management operation of an image (see
4561<a href="command-line-options.html#profile">-profile</a>). Choose from these intents: <code>Absolute,
4562Perceptual, Relative, Saturation</code>.</p>
4563
4564<p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4565
4566<p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4567
4568<div style="margin: auto;">
4569 <h3 class="magick-header"><a id="interlace"></a>-interlace <var>type</var></h3>
4570</div>
4571
4572<p class="magick-description">the type of interlacing scheme.</p>
4573
4574<p>Choose from:</p>
4575
4576<pre>
4577none
4578line
4579plane
4580partition
4581JPEG
4582GIF
4583PNG
4584</pre>
4585
4586<p>This option is used to specify the type of interlacing scheme for raw image
4587formats such as <code>RGB</code> or <code>YUV</code>.</p>
4588
4589<p><code>None</code> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4590
4591<p><code>Line</code> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4592
4593<p><code>Plane</code> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4594
4595<p><code>Partition</code> is like plane except the different planes are saved to
4596individual files (e.g. image.R, image.G, and image.B).</p>
4597
4598<p>Use <code>Line</code> or <code>Plane</code> to create an <code>interlaced
4599PNG</code> or <code>GIF</code> or <code>progressive JPEG</code> image.</p>
4600
4601<p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4602interlace</a>.</p>
4603
4604<div style="margin: auto;">
4605 <h3 class="magick-header"><a id="interpolate"></a>-interpolate <var>type</var></h3>
4606</div>
4607
4608<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>
4609
4610<p>When looking up the color of a pixel using a non-integer floating point
4611value, you typically fall in between the pixel colors defined by the source
4612image. This setting determines how the color is determined from the colors of
4613the pixels surrounding that point. That is how to determine the color of a
4614point that falls between two, or even four different colored pixels. </p>
4615
4616<dl class="dl-horizontal">
4617 <dt>integer</dt>
4618 <dd>The color of the top-left pixel (floor function)</dd>
4619 <dt>nearest-neighbor</dt>
4620 <dd>The nearest pixel to the lookup point (rounded function)</dd>
4621 <dt>average</dt>
4622 <dd>The average color of the surrounding four pixels</dd>
4623 <dt>bilinear</dt>
4624 <dd>A double linear interpolation of pixels (the default)</dd>
4625 <dt>mesh</dt>
4626 <dd>Divide area into two flat triangular interpolations</dd>
4627 <dt>bicubic</dt>
4628 <dd>Fitted bicubic-spines of surrounding 16 pixels</dd>
4629 <dt>spline</dt>
4630 <dd>Direct spline curves (colors are blurred)</dd>
4631 <dt>filter</dt>
4632 <dd>Use resize <a href="command-line-options.html#filter">-filter</a> settings</dd>
4633</dl>
4634
4635<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>
4636
4637<p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4638
4639<p>See also <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a>, for control of the
4640lookup for positions outside the boundaries of the image. </p>
4641
4642
4643<div style="margin: auto;">
4644 <h3 class="magick-header"><a id="interline-spacing"></a>-interline-spacing <var>value</var></h3>
4645</div>
4646
4647<p class="magick-description">the space between two text lines.</p>
4648
4649<div style="margin: auto;">
4650 <h3 class="magick-header"><a id="interword-spacing"></a>-interword-spacing <var>value</var></h3>
4651</div>
4652
4653<p class="magick-description">the space between two words.</p>
4654
4655<div style="margin: auto;">
4656 <h3 class="magick-header"><a id="kerning"></a>-kerning <var>value</var></h3>
4657</div>
4658
4659<p class="magick-description">the space between two letters.</p>
4660
4661<div style="margin: auto;">
4662 <h3 class="magick-header"><a id="kuwahara"></a>-kuwahara <var>radius</var><br>-kuwahara <var>radius</var>x<var>sigma</var></h3>
4663</div>
4664
4665<p class="magick-description">edge preserving noise reduction filter.</p>
4666
4667<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>
4668
4669
4670<div style="margin: auto;">
4671 <h3 class="magick-header"><a id="label"></a>-label <var>name</var></h3>
4672</div>
4673
4674<p class="magick-description">assign a label to an image.</p>
4675
4676<p>Use this option to assign a specific label to the image, as it is read in
4677or created. You can use the <a href="command-line-options.html#set">-set</a> operation to re-assign
4678a the labels of images already read in. Image formats such as TIFF, PNG,
4679MIFF, supports saving the label information with the image.</p>
4680
4681<p>When saving an image to a <var>PostScript</var> file, any label
4682assigned to an image is used as a header string to print above the postscript
4683image. </p>
4684
4685<p>You can include the image filename, type, width, height, or other image
4686attribute by embedding special format character. See <a href="escape.html">Format and Print Image
4687Properties</a> for details of the percent escape codes.</p>
4688
4689<p>For example,</p>
4690
4691<pre>
4692-label "%m:%f %wx%h" bird.miff
4693</pre>
4694
4695<p>assigns an image label of <code>MIFF:bird.miff 512x480</code> to the
4696"<code>bird.miff</code>" image and whose width is 512 and height is 480, as it
4697is read in. If a <a href="command-line-options.html#label">+label</a> option was used instead, any
4698existing label present in the image would be used. You can remove all labels
4699from an image by assigning the empty string. </p>
4700
4701<p>A label is not drawn on the image, but is embedded in the image datastream
4702via <var>Label</var> tag or similar mechanism. If you want the label to be
4703visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
4704during the final processing in the creation of an image montage.</p>
4705
4706<p>If the first character of <var>string</var> is <var>@</var>, the image label is read from a file titled by the
4707remaining characters in the string. Labels in a file are literal, no embedded
4708formatting characters are recognized.</p>
4709
4710
4711<div style="margin: auto;">
4712 <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>
4713</div>
4714
4715<p class="magick-description">perform local adaptive threshold.</p>
4716
4717<p>Adaptively threshold each pixel based on the value of pixels in a
4718surrounding window. If the current pixel is lighter than this average plus
4719the optional <code>offset</code>, then it is made white, otherwise it is made
4720black. Small variations in pixel values such as found in scanned documents
4721can be ignored if offset is positive. A negative offset will make it more
4722sensitive to those small variations. </p>
4723
4724<p>This is commonly used to threshold images with an uneven background. It is
4725based on the assumption that average color of the small window is the
4726the local background color, from which to separate the foreground color. </p>
4727
4728
4729<div style="margin: auto;">
4730 <h3 class="magick-header"><a id="layers"></a>-layers <var>method</var></h3>
4731</div>
4732
4733<p class="magick-description">handle multiple images forming a set of image layers or animation frames.</p>
4734
4735<p>Perform various image operation methods to a ordered sequence of images
4736which may represent either a set of overlaid 'image layers', a GIF disposal
4737animation, or a fully-'coalesced' animation sequence. </p>
4738
4739<table class="table table-condensed table-striped">
4740 <tbody>
4741 <tr>
4742 <th style="width: 8%">Method</th>
4743 <th>Description</th>
4744 </tr>
4745
4746 <tr>
4747 <td>compare-any</td>
4748 <td>Crop the second and later frames to the smallest rectangle
4749 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>
4750 </tr>
4751
4752 <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
4753 working, especially when animation used layer disposal methods such as
4754 '<code>Previous</code>' or '<code>Background</code>'. </td>
4755 </tr>
4756
4757 <tr>
4758 <td>compare-clear</td>
4759 <td>As '<code>compare-any</code>' but crop to the bounds of any
4760 opaque pixels which become transparent in the second frame. That is the
4761 smallest image needed to mask or erase pixels for the next frame. </td>
4762 </tr>
4763
4764 <tr>
4765 <td>compare-overlay</td>
4766 <td>As '<code>compare-any</code>' but crop to pixels that add
4767 extra color to the next image, as a result of overlaying color pixels.
4768 That is the smallest single overlaid image to add or change colors. </td>
4769 </tr>
4770
4771 <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose">-compose</a> alpha
4772 composition method '<code>change-mask</code>', to reduce the image to
4773 just the pixels that need to be overlaid. </td>
4774 </tr>
4775
4776 <tr>
4777 <td>coalesce</td>
4778 <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
4779 current image sequence to form a fully defined animation sequence, as
4780 it should be displayed. Effectively converting a GIF animation into a
4781 'film strip'-like animation. </td>
4782 </tr>
4783
4784 <tr>
4785 <td>composite</td>
4786 <td>Alpha Composition of two image lists, separated by a
4787 "<code>null:</code>" image, with the destination image list first, and
4788 the source images last. An image from each list are composited
4789 together until one list is finished. The separator image and source
4790 image lists are removed. </td>
4791 </tr>
4792
4793
4794 <tr><td></td>
4795 <td>The <a href="command-line-options.html#geometry">-geometry</a> offset is adjusted according
4796 to <a href="command-line-options.html#gravity">-gravity</a> in accordance of the virtual
4797 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
4798 added to the final composite positioning of each image. </td> </tr>
4799
4800 <tr><td></td>
4801 <td>If one of the image lists only contains one image, that image is
4802 applied to all the images in the other image list, regardless of which
4803 list it is. In this case it is the image meta-data of the list which
4804 preserved. </td>
4805 </tr>
4806
4807
4808 <tr>
4809 <td>dispose</td>
4810 <td>This like '<code>coalesce</code>' but shows the look of
4811 the animation after the layer disposal method has been applied, before
4812 the next sub-frame image is overlaid. That is the 'dispose' image that
4813 results from the application of the GIF <a href="command-line-options.html#dispose">-dispose</a> method. This allows you to check what
4814 is going wrong with a particular animation you may be developing.
4815 </td>
4816 </tr>
4817
4818 <tr>
4819 <td>flatten</td>
4820 <td>Create a canvas the size of the first images virtual
4821 canvas using the current <a href="command-line-options.html#background">-background</a> color,
4822 and <a href="command-line-options.html#compose">-compose</a> each image in turn onto that
4823 canvas. Images falling outside that canvas is clipped. Final
4824 image will have a zero virtual canvas offset. </td>
4825 </tr>
4826
4827 <tr><td></td>
4828 <td>This usually used as one of the final 'image layering' operations
4829 overlaying all the prepared image layers into a final image. </td>
4830 </tr>
4831
4832 <tr><td></td>
4833 <td>For a single image this method can also be used to fillout a virtual
4834 canvas with real pixels, or to underlay an opaque color to remove
4835 transparency from an image.</td>
4836 </tr>
4837
4838
4839 <tr>
4840 <td>merge</td>
4841 <td>As 'flatten' method but merging all the given image
4842 layers to create a new layer image just large enough to hold all the
4843 image without clipping or extra space. The new images virtual offset
4844 will preserve the position of the new layer, even if this offset is
4845 negative. The virtual canvas size of the first image is preserved.
4846 </td>
4847 </tr>
4848
4849 <tr><td></td><td>Caution is advised when handling image layers with
4850 negative offsets as few image file formats handle them correctly.
4851 Following this operation method with <a href="command-line-options.html#repage">+repage</a>
4852 will remove the layer offset, and create an image in which all the
4853 overlaid image positions relative to each other is preserved, though
4854 not necessarily exactly where you specified them.
4855 </td>
4856 </tr>
4857
4858 <tr><td></td><td>See also 'trim-bounds' below which is closely related but
4859 without doing the'flatten' to merge the images together. </td>
4860 </tr>
4861
4862 <tr>
4863 <td>mosaic</td>
4864 <td>As 'flatten' method but expanding the initial canvas size
4865 of the first image in a positive direction only so as to hold all the
4866 image layers. However as a virtual canvas is 'locked' to the origin,
4867 by its own definition, image layers with a negative offsets will still
4868 become clipped by the top and left edges. See 'merge' or 'trim-bounds'
4869 if this could be a problem. </td>
4870
4871 </tr>
4872
4873 <tr><td></td><td>This method is commonly used to layout individual image
4874 using various offset but without knowing the final canvas size. The
4875 resulting image will, like 'flatten' not have any virtual offset, so
4876 can be saved to any image file format. </td>
4877 </tr>
4878
4879
4880 <tr>
4881 <td>optimize</td>
4882 <td>Optimize a coalesced animation, into GIF animation using
4883 a number of general techniques. This currently a short cut to
4884 apply both the '<code>optimize-frame</code>', and
4885 '<code>optimize-transparency</code>' methods but may be expanded to
4886 include other optimization methods as they are developed. </td>
4887 </tr>
4888
4889 <tr>
4890 <td>optimize-frame</td>
4891 <td>Optimize a coalesced animation, into GIF animation by
4892 reducing the number of pixels per frame as much as possible by
4893 attempting to pick the best layer disposal method to use, while ensuring
4894 the result will continue to animate properly. </td>
4895 </tr>
4896
4897 <tr><td></td><td> There is no guarantee that the best optimization is found.
4898 But then no reasonably fast GIF optimization algorithm can do this.
4899 However this does seem to do better than most other GIF frame
4900 optimizers seen. </td>
4901 </tr>
4902
4903 <tr>
4904 <td>optimize-plus</td>
4905 <td>As '<code>optimize-frame</code>' but attempt to improve the
4906 overall optimization by adding extra frames to the animation, without
4907 changing the final look or timing of the animation. The frames are
4908 added to attempt to separate the clearing of pixels from the
4909 overlaying of new additional pixels from one animation frame to the
4910 next. If this does not improve the optimization (for the next frame
4911 only), it will fall back to the results of the previous normal
4912 '<code>optimize-frame</code>' technique. </td>
4913 </tr>
4914
4915 <tr><td></td><td>There is the possibility that the change in the disposal
4916 style will result in a worsening in the optimization of later frames,
4917 though this is unlikely. In other words there no guarantee that it is
4918 better than the normal '<code>optimize-frame</code>' technique. For some
4919 animations however you can get a vast improvement in the final
4920 animation size. </td>
4921 </tr>
4922
4923 <tr>
4924 <td>optimize-transparency</td>
4925 <td>Given a GIF animation, replace any pixel in the sub-frame
4926 overlay images with transparency, if it does not change the resulting
4927 animation by more than the current <a href="command-line-options.html#fuzz">-fuzz</a> factor.
4928 </td>
4929 </tr>
4930
4931 <tr><td></td><td>This should allow a existing frame optimized GIF animation
4932 to compress into a smaller file size due to larger areas of one
4933 (transparent) color rather than a pattern of multiple colors repeating
4934 the current disposed image of the last frame. </td>
4935 </tr>
4936
4937 <tr>
4938 <td>remove-dups</td>
4939 <td>Remove (and merge time delays) of duplicate consecutive
4940 images, so as to simplify layer overlays of coalesced animations.
4941 </td>
4942 </tr>
4943
4944 <tr><td></td><td>Usually this a result of using a constant time delay
4945 across the whole animation, or after a larger animation was split into
4946 smaller sub-animations. The duplicate frames could also have been
4947 used as part of some frame optimization methods. </td>
4948 </tr>
4949
4950 <tr>
4951 <td>remove-zero</td>
4952 <td>Remove any image with a zero time delay, unless ALL the
4953 images have a zero time delay (and is not a proper timed animation, a
4954 warning is then issued). </td>
4955 </tr>
4956
4957 <tr><td></td><td>In a GIF animation, such images are usually frames which
4958 provide partial intermediary updates between the frames that are
4959 actually displayed to users. These frames are usually added for
4960 improved frame optimization in GIF animations. </td>
4961 </tr>
4962
4963 <tr>
4964 <td>trim-bounds</td>
4965 <td>Find the bounds of all the images in the current
4966 image sequence, then adjust the offsets so all images are contained on
4967 a minimal positive canvas. None of the image data is modified or
4968 merged, only the individual image virtual canvas size and offset.
4969 All the images is given the same canvas size, and and will have
4970 a positive offset, but will remain in the same position relative to
4971 each other. As a result of the minimal canvas size at least one image
4972 will touch every edge of that canvas. The image data touching those
4973 edges however may be transparent. </td>
4974 </tr>
4975
4976 <tr><td></td><td>The result is much like if you used 'merge' followed by a
4977 <a href="command-line-options.html#repage">+repage</a> option, except that all the images
4978 have been kept separate. If 'flatten' is used after using
4979 'trim-bounds' you will get the same result. </td>
4980 </tr>
4981
4982 </tbody>
4983</table>
4984
4985<p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
4986
4987<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
4988the 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
4989GIF <a href="command-line-options.html#dispose">-dispose</a> and <a href="command-line-options.html#delay">-delay</a>
4990settings. </p>
4991
4992
4993<div style="margin: auto;">
4994 <h3 class="magick-header"><a id="level"></a>-level <var>black_point</var>{,<var>white_point</var>}{<var>%</var>}{,<var>gamma</var>}</h3>
4995</div>
4996
4997<p class="magick-description">adjust the level of image channels.</p>
4998
4999<p>Given one, two or three values delimited with commas: black-point,
5000white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
5001white points range from 0 to <var>QuantumRange</var>, or from 0 to
5002100%; if the white point is omitted it is set to (<var>QuantumRange</var> - black_point), so as to center contrast changes.
5003If a <code>%</code> sign is present anywhere in the string, both black and white
5004points 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
5005default of 1.0 (no gamma correction) is assumed.</p>
5006
5007<p>In normal usage (<code>-level</code>) the image values are stretched so that
5008the given '<code>black_point</code>' value in the original image is set to zero
5009(or black), while the given '<code>white_point</code>' value is set to <var>QuantumRange</var> (or white). This provides you with direct
5010contrast adjustments to the image. The '<code>gamma</code>' of the resulting
5011image will then be adjusted. </p>
5012
5013<p>From ImageMagick v6.4.1-9 using the plus form of the operator
5014(<code>+level</code>) or adding the special '!' flag anywhere in the argument
5015list, will cause the operator to do the reverse of the level adjustment. That
5016is a zero, or <var>QuantumRange</var> value (black, and white, resp.)
5017in the original image, is adjusted to the given level values, allowing you to
5018de-contrast, or compress the channel values within the image. The
5019'<code>gamma</code>' is adjusted before the level adjustment to de-contrast the
5020image is made. </p>
5021
5022<p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
5023setting are adjusted (defaults to RGB color channels only), allowing you to
5024limit the effect of this operator. </p>
5025
5026<p>Please note that the transparency channel is treated as 'matte'
5027values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
5028
5029
5030<div style="margin: auto;">
5031 <h3 class="magick-header"><a id="level-colors"></a>-level-colors {<var>black_color</var>}{,}{<var>white_color</var>}</h3>
5032</div>
5033
5034<p class="magick-description">adjust the level of an image using the provided dash separated colors.</p>
5035
5036<p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
5037value value for each color channel is determined by the
5038'<code>black_color</code>' and '<code>white_color</code>' colors given (as
5039described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
5040
5041<p>This effectually means the colors provided to <code>-level-colors</code>
5042is mapped to become 'black' and 'white' respectively, with all the other
5043colors linearly adjusted (or clipped) to match that change. Each channel is
5044adjusted separately using the channel values of the colors specified. </p>
5045
5046<p>On the other hand the plus form of the operator (<code>+level-colors</code>)
5047will map the image color 'black' and 'white' to the given colors
5048respectively, resulting in a gradient (de-contrasting) tint of the image to
5049those colors. This can also be used to convert a plain gray-scale image into a
5050one using the gradient of colors specified. </p>
5051
5052<p>By supplying a single color with a comma separator either before or after
5053that color, will just replace the respective 'black' or 'white' point
5054respectively. But if no comma separator is provided, the given color is
5055used for both the black and white color points, making the operator either
5056threshold the images around that color (- form) or set all colors to that
5057color (+ form). </p>
5058
5059
5060<div style="margin: auto;">
5061 <h3 class="magick-header"><a id="limit"></a>-limit <var>type value</var></h3>
5062</div>
5063
5064<p class="magick-description">Set the pixel cache resource limit.</p>
5065
5066<p>Choose from: <code>area</code>, <code>disk</code>, <code>file</code>,
5067<code>map</code>, <code>memory</code>, <code>thread</code>, or <code>time</code>.</p>
5068
5069<p>The value for <code>file</code> is in number of files. The other limits are
5070in bytes. Define arguments for the memory, map, area, and disk resource limits
5071with SI prefixes (.e.g 100MB).</p>
5072
5073<p>By default the limits are 768 files, 3GB of image area, 1.5GiB memory, 3GiB
5074memory map, and 18.45EB of disk. These limits are adjusted relative to the
5075available resources on your computer if this information is available. When
5076any limit is reached, ImageMagick fails in some fashion but attempts to take
5077compensating actions, if possible. For example, the following limits
5078memory:</p>
5079
5080<pre>
5081-limit memory 32MiB -limit map 64MiB
5082</pre>
5083
5084<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>
5085
5086<pre>
5087-&gt; identify -list resource
5088Resource limits:
5089 Width: 100MP
5090 Height: 100MP
5091 Area: 25.181GB
5092 Memory: 11.726GiB
5093 Map: 23.452GiB
5094 Disk: unlimited
5095 File: 768
5096 Thread: 12
5097 Throttle: 0
5098 Time: unlimited
5099</pre>
5100
5101<p>Requests for pixel storage to keep intermediate images are satisfied by one
5102of three resource categories: in-memory pool, memory-mapped files pool, and
5103disk pool (in that order) depending on the <a href="command-line-options.html#limit">‑limit</a> settings
5104and whether the system honors a resource request. If the total size of
5105allocated pixel storage in the given pool reaches the corresponding limit, the
5106request is passed to the next pool. Additionally, requests that exceed the
5107<code>area</code> limit automagically are allocated on disk.</p>
5108
5109<p>To illustrate how ImageMagick utilizes resource limits, consider a typical
5110image resource request. First, ImageMagick tries to allocate the pixels in
5111memory. The request might be denied if the resource request exceeds the
5112<code>memory</code> limit or if the system does not honor the request. If
5113a memory request is not honored, the pixels are allocated to disk and the file
5114is memory-mapped. However, if the allocation request exceeds the
5115<code>map</code> limit, the resource allocation goes to disk. In all cases, if
5116the resource request exceeds the <code>area</code> limit, the pixels are
5117automagically cached to disk. If the disk has a hard limit, the program
5118fails.</p>
5119
5120<p>In most cases you simply do not need to concern yourself with resource
5121limits. ImageMagick chooses reasonable defaults and most images do not tax
5122your computer resources. Where limits do come in handy is when you process
5123images that are large or on shared systems where ImageMagick can consume all
5124or most of the available memory. In this case, the ImageMagick workflow slows
5125other processes or, in extreme cases, brings the system to a halt. Under
5126these circumstances, setting limits give some assurances that the ImageMagick
5127workflow will not interfere with other concurrent uses of the computer. For
5128example, assume you have a web interface that processes images uploaded from
5129the Internet. To assure ImageMagick does not exceed 10MiB of memory you can
5130simply set the area limit to 10MiB:</p>
5131
5132<pre>
5133-limit area 10MB
5134</pre>
5135
5136<p>Now whenever a large image is processed, the pixels are automagically
5137cached to disk instead of memory. This of course implies that large images
5138typically process very slowly, simply because pixel processing in memory can
5139be an order of magnitude faster than on disk. Because your web site users
5140might inadvertently upload a huge image to process, you should set a disk
5141limit as well:</p>
5142
5143<pre>
5144-limit area 10MB -limit disk 500MB
5145</pre>
5146
5147<p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
5148
5149<p>In addition to command-line resource limit option, resources can be set
5150with <a href="resources.html#environment">environment variables</a>. Set the
5151environment variables <code>MAGICK_AREA_LIMIT</code>,
5152<code>MAGICK_DISK_LIMIT</code>, <code>MAGICK_FILE_LIMIT</code>,
5153<code>MAGICK_MEMORY_LIMIT</code>, <code>MAGICK_MAP_LIMIT</code>,
5154<code>MAGICK_THREAD_LIMIT</code>, <code>MAGICK_TIME_LIMIT</code> for limits of
5155image area, disk space, open files, heap memory, memory map, number of threads
5156of execution, and maximum elapsed time in seconds respectively.</p>
5157
5158<p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
5159their commands and then scouring the generated output for references to the
5160pixel cache, in order to determine how the pixel cache was allocated and how
5161resources were consumed. Advanced Unix/Linux users can pipe that output
5162through <code>grep memory|open|destroy|disk</code> for more readable sifting.
5163</p>
5164
5165<p>For more about ImageMagick's use of resources, see the section <b>Cache
5166Storage and Resource Requirements</b> on the <a href="architecture.html#cache%0A">Architecture</a> page. </p>
5167
5168<div style="margin: auto;">
5169 <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>
5170</div>
5171
5172<p class="magick-description">Linear with saturation stretch.</p>
5173
5174<p>This is very similar to <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
5175and uses a 'histogram bin' to determine the range of color values that needs to
5176be stretched. However it then stretches those colors using the <a href="command-line-options.html#level">-level</a> operator.</p>
5177
5178<p>As such while the initial determination may have 'binning' round off
5179effects, the image colors are stretched mathematically, rather than using the
5180histogram bins. This makes the operator more accurate. </p>
5181
5182<p>note however that a <a href="command-line-options.html#linear-stretch">-linear-stretch</a> of
5183'<code>0</code>' does nothing, while a value of '<code>1</code>' does a near
5184perfect stretch of the color range. </p>
5185
5186<p>See also <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect'
5187normalization of mathematical images. </p>
5188
5189<p>This operator is under review for re-development. </p>
5190
5191
5192<div style="margin: auto;">
5193 <h3 class="magick-header"><a id="linewidth"></a>-linewidth</h3>
5194</div>
5195
5196<p class="magick-description">the line width for subsequent draw operations.</p>
5197
5198<div style="margin: auto;">
5199 <h3 class="magick-header"><a id="liquid-rescale"></a>-liquid-rescale <var>geometry</var></h3>
5200</div>
5201
5202<p class="magick-description">rescale image with seam-carving.</p>
5203
5204<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5205
5206<div style="margin: auto;">
5207 <h3 class="magick-header"><a id="list"></a>-list <var>type</var></h3>
5208</div>
5209
5210<p class="magick-description">Print a list of supported arguments for various options or settings. Choose from these list types:</p>
5211
5212<pre class="pre-scrollable">
5213Align
5214Alpha
5215Boolean
5216Cache
5217Channel
5218Class
5219ClipPath
5220Coder
5221Color
5222Colorspace
5223Command
5224Complex
5225Compose
5226Compress
5227Configure
5228DataType
5229Debug
5230Decoration
5231Delegate
5232Direction
5233Dispose
5234Distort
5235Dither
5236Endian
5237Evaluate
5238FillRule
5239Filter
5240Font
5241Format
5242Function
5243Gravity
5244Intensity
5245Intent
5246Interlace
5247Interpolate
5248Kernel
5249Layers
5250LineCap
5251LineJoin
5252List
5253Locale
5254LogEvent
5255Log
5256Magic
5257Method
5258Metric
5259Mime
5260Mode
5261Morphology
5262Module
5263Noise
5264Orientation
5265PixelIntensity
5266Policy
5267PolicyDomain
5268PolicyRights
5269Preview
5270Primitive
5271QuantumFormat
5272Resource
5273SparseColor
5274Statistic
5275Storage
5276Stretch
5277Style
5278Threshold
5279Type
5280Units
5281Validate
5282VirtualPixel
5283</pre>
5284
5285<p>These lists vary depending on your version of ImageMagick. Use "<code>-list
5286list</code>" to get a complete listing of all the "<code>-list</code>" arguments
5287available:</p>
5288
5289<pre>
5290identify -list list
5291</pre>
5292
5293<div style="margin: auto;">
5294 <h3 class="magick-header"><a id="log"></a>-log <var>string</var></h3>
5295</div>
5296
5297<p class="magick-description">Specify format for debug log.</p>
5298
5299<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>
5300
5301<p>You can display the following components by embedding special format
5302characters:</p>
5303
5304<dl class="dl-horizontal">
5305<dt>%d</dt><dd>domain</dd>
5306<dt>%e</dt><dd>event</dd>
5307<dt>%f</dt><dd>function</dd>
5308<dt>%l</dt><dd>line</dd>
5309<dt>%m</dt><dd>module</dd>
5310<dt>%p</dt><dd>process ID</dd>
5311<dt>%r</dt><dd>real CPU time</dd>
5312<dt>%t</dt><dd>wall clock time</dd>
5313<dt>%u</dt><dd>user CPU time</dd>
5314<dt>%%</dt><dd>percent sign</dd>
5315<dt>\n</dt><dd>newline</dd>
5316<dt>\r</dt><dd>carriage return</dd>
5317</dl>
5318
5319<p>For example:</p>
5320
5321<pre>
5322convert -debug coders -log "%u %m:%l %e" in.gif out.png
5323</pre>
5324
5325<p>The default behavior is to print all of the components.</p>
5326
5327<div style="margin: auto;">
5328 <h3 class="magick-header"><a id="loop"></a>-loop <var>iterations</var></h3>
5329</div>
5330
5331<p class="magick-description">add Netscape loop extension to your GIF animation.</p>
5332
5333<p>Set iterations to zero to repeat the animation an infinite number of times,
5334otherwise the animation repeats itself up to <var>iterations</var>
5335times.</p>
5336
5337<div style="margin: auto;">
5338 <h3 class="magick-header"><a id="lowlight-color"></a>-lowlight-color <var>color</var></h3>
5339</div>
5340
5341<p class="magick-description">when comparing images, de-emphasize pixel differences with this color.</p>
5342
5343<div style="margin: auto;">
5344 <h3 class="magick-header"><a id="magnify"></a>-magnify</h3>
5345</div>
5346
5347<p class="magick-description">double the size of the image with pixel art scaling.</p>
5348
5349
5350<div style="margin: auto;">
5351 <h3 class="magick-header"><a id="map"></a>-map <var>type</var></h3>
5352</div>
5353
5354<p class="magick-description">Display image using this <var>type</var>.</p>
5355
5356<p>Choose from these <var>Standard Colormap</var> types:</p>
5357
5358<pre>
5359best
5360default
5361gray
5362red
5363green
5364blue
5365</pre>
5366
5367<p>The <var>X server</var> must support the <var>Standard
5368Colormap</var> you choose, otherwise an error occurs. Use <code>list</code> as
5369the type and <code>display</code> searches the list of colormap types in
5370<code>top-to-bottom</code> order until one is located. See <var>xstdcmap(1)</var> for one way of creating Standard Colormaps.</p>
5371
5372
5373<div style="margin: auto;">
5374 <h3 class="magick-header"><a id="map_stream_"></a>-map <var>components</var></h3>
5375</div>
5376
5377<p class="magick-description">pixel map.</p>
5378
5379<p>Here are the valid components of a map:</p>
5380
5381<dl class="dl-horizontal">
5382<dt>r</dt><dd> red pixel component</dd>
5383<dt>g</dt><dd> green pixel component</dd>
5384<dt>b</dt><dd> blue pixel component</dd>
5385<dt>a</dt><dd> alpha pixel component (0 is transparent)</dd>
5386<dt>o</dt><dd> opacity pixel component (0 is opaque)</dd>
5387<dt>i</dt><dd> grayscale intensity pixel component</dd>
5388<dt>c</dt><dd> cyan pixel component</dd>
5389<dt>m</dt><dd> magenta pixel component</dd>
5390<dt>y</dt><dd> yellow pixel component</dd>
5391<dt>k</dt><dd> black pixel component</dd>
5392<dt>p</dt><dd> pad component (always 0)</dd>
5393</dl>
5394
5395<p>You can specify as many of these components as needed in any order (e.g.
5396bgr). The components can repeat as well (e.g. rgbr).</p>
5397
5398
5399<div style="margin: auto;">
5400 <h3 class="magick-header"><a id="mask"></a>-mask
5401<var>filename</var></h3>
5402</div>
5403
5404<p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
5405
5406<p>This the same as using a mask used for composite masking operations, with
5407grayscale values causing blended updates of the image the mask is attached to.
5408</p>
5409
5410<p>Use <a href="command-line-options.html#mask">+mask</a> to remove the mask from images.</p>
5411
5412<p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
5413but with strict boolean masking. </p>
5414
5415<div style="margin: auto;">
5416 <h3 class="magick-header"><a id="mattecolor"></a>-mattecolor <var>color</var></h3>
5417</div>
5418
5419<p class="magick-description">Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</p>
5420
5421<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5422
5423<p>The default matte color is <code>#BDBDBD</code>, <span style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5424
5425<div style="margin: auto;">
5426 <h3 class="magick-header"><a id="maximum"></a>-maximum</h3>
5427</div>
5428
5429<p class="magick-description">return the maximum intensity of an image sequence.</p>
5430
5431<p>Select the 'maximum' value from all the surrounding pixels. </p>
5432
5433<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5434name. </p>
5435
5436<div style="margin: auto;">
5437 <h3 class="magick-header"><a id="median"></a>-median <var>geometry</var></h3>
5438</div>
5439
5440<p class="magick-description">apply a median filter to the image.</p>
5441
5442<p>Select the 'middle' value from all the surrounding pixels. </p>
5443
5444<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5445name. </p>
5446
5447<div style="margin: auto;">
5448 <h3 class="magick-header"><a id="mean-shift"></a>-mean-shift <var>width</var>x<var>height</var>{<var>+distance</var>{%}}</h3>
5449</div>
5450
5451<p class="magick-description">image noise removal and color reduction/segmentation (e.g. -mean-shift 7x7+10%).</p>
5452
5453<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>
5454
5455<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>
5456
5457<div style="margin: auto;">
5458 <h3 class="magick-header"><a id="metric"></a>-metric <var>type</var></h3>
5459</div>
5460
5461<p class="magick-description">Output to STDERR a measure of the differences between images according to the <var>type</var> given metric.</p>
5462
5463<p>Choose from:</p>
5464
5465<dl class="dl-horizontal">
5466<dt>AE</dt><dd> absolute error count, number of different pixels (-fuzz effected)</dd>
5467<dt>FUZZ</dt><dd> mean color distance</dd>
5468<dt>MAE</dt><dd> mean absolute error (normalized), average channel error distance</dd>
5469<dt>MEPP</dt><dd> mean error per pixel (normalized mean error, normalized peak error)</dd>
5470<dt>MSE</dt><dd> mean error squared, average of the channel error squared</dd>
5471<dt>NCC</dt><dd> normalized cross correlation</dd>
5472<dt>PAE</dt><dd> peak absolute (normalized peak absolute)</dd>
5473<dt>PHASH</dt><dd> perceptual hash</dd>
5474<dt>PSNR</dt><dd> peak signal to noise ratio</dd>
5475<dt>RMSE</dt><dd> root mean squared (normalized root mean squared)</dd>
5476</dl>
5477
5478<p>Control the '<code>AE</code>', or absolute count of pixels that are different,
5479with the <a href="command-line-options.html#fuzz">-fuzz</a> factor (ignore pixels which
5480only changed by a small amount). Use '<code>PAE</code>' to find the
5481size of the <a href="command-line-options.html#fuzz">-fuzz</a> factor needed to make all pixels
5482'similar', while '<code>MAE</code>' determines the factor needed
5483for about half the pixels to be similar. </p>
5484
5485<p>The '<code>MEPP</code>' metric returns three different metrics
5486('<code>MAE</code>', '<code>MAE</code>' normalized, and '<code>PAE</code>'
5487normalized) from a single comparison run. </p>
5488
5489<p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5490metric</a> option.</p>
5491
5492
5493<div style="margin: auto;">
5494 <h3 class="magick-header"><a id="minimum"></a>-minimum</h3>
5495</div>
5496
5497<p class="magick-description">return the minimum intensity of an image sequence.</p>
5498
5499<p>Select the 'minimal' value from all the surrounding pixels. </p>
5500
5501<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5502name. </p>
5503
5504
5505
5506<div style="margin: auto;">
5507 <h3 class="magick-header"><a id="mode"></a>-mode <var>geometry</var></h3>
5508</div>
5509
5510<p class="magick-description">make each pixel the \'predominant color\' of the neighborhood.'</p>
5511
5512<div style="margin: auto;">
5513 <h3 class="magick-header">-mode <var>value</var></h3>
5514</div>
5515
5516<p class="magick-description">Mode of operation.</p>
5517
5518<p>Choose the <var>value</var> from these styles: <code>Frame,
5519Unframe, or Concatenate</code></p>
5520
5521<p>Use the <a href="command-line-options.html#list">-list</a> option with a '<code>Mode</code>' argument
5522for a list of <a href="command-line-options.html#mode">-mode</a> arguments available in your
5523ImageMagick installation.</p>
5524
5525
5526<div style="margin: auto;">
5527 <h3 class="magick-header"><a id="modulate"></a>-modulate <var>brightness</var>[,<var>saturation</var>,<var>hue</var>]</h3>
5528</div>
5529
5530<p class="magick-description">Vary the <var>brightness</var>, <var>saturation</var>, and <var>hue</var> of an image.</p>
5531
5532<p>The arguments are given as a percentages of variation. A value of 100 means
5533no change, and any missing values are taken to mean 100.</p>
5534
5535<p>The <var>brightness</var> is a multiplier of the overall
5536brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5537twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5538before and after. </p>
5539
5540<p>The <var>saturation</var> controls the amount of color in an
5541image. For example, 0 produce a grayscale image, while a large value such as
5542200 produce a very colorful, 'cartoonish' color.</p>
5543
5544<p>The <var>hue</var> argument causes a "rotation" of the colors
5545within the image by the amount specified. For example, 50 results in
5546a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5547A value of either 0 or 200 results in a complete 180 degree rotation of the
5548image. Using a value of 300 is a 360 degree rotation resulting in no change to
5549the original image. </p>
5550
5551<p>For example, to increase the color brightness by 20% and decrease the color
5552saturation by 10% and leave the hue unchanged, use <a href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5553
5554<p>Use <a href="command-line-options.html#set">-set</a> attribute of '<code>option:modulate:colorspace</code>' to specify which colorspace to
5555modulate. 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>
5556
5557<pre>
5558convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png
5559</pre>
5560
5561<div style="margin: auto;">
5562 <h3 class="magick-header"><a id="moments"></a>-moments</h3>
5563</div>
5564
5565<p class="magick-description">report image moments and perceptual hash.</p>
5566
5567
5568<div style="margin: auto;">
5569 <h3 class="magick-header"><a id="monitor"></a>-monitor</h3>
5570</div>
5571
5572<p class="magick-description">monitor progress.</p>
5573
5574
5575<div style="margin: auto;">
5576 <h3 class="magick-header"><a id="monochrome"></a>-monochrome</h3>
5577</div>
5578
5579<p class="magick-description">transform the image to black and white.</p>
5580
5581<div style="margin: auto;">
5582 <h3 class="magick-header"><a id="morph"></a>-morph <var>frames</var></h3>
5583</div>
5584
5585<p class="magick-description">morphs an image sequence.</p>
5586
5587<p>Both the image pixels and size are linearly interpolated to give the
5588appearance of a metamorphosis from one image to the next, over all the images
5589in 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>
5590argument determine how many images to interpolate between each image. </p>
5591
5592
5593<div style="margin: auto;">
5594 <h3 class="magick-header"><a id="morphology"></a>-morphology</h3>
5595 <h3 class="magick-header">-morphology <var>method</var> <var>kernel</var></h3>
5596</div>
5597
5598<p class="magick-description">apply a morphology method to the image.</p>
5599
5600<p>Until I get around to writing an option summary for this, see <a href="http://www.imagemagick.org/Usage/morphology/">IM Usage Examples,
5601Morphology</a>. </p>
5602
5603
5604<div style="margin: auto;">
5605 <h3 class="magick-header"><a id="mosaic"></a>-mosaic</h3>
5606</div>
5607
5608<p class="magick-description">an simple alias for the <a href="command-line-options.html#layers">-layers</a> method "mosaic"</p>
5609
5610
5611<div style="margin: auto;">
5612 <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>
5613</div>
5614
5615<p class="magick-description">simulate motion blur.</p>
5616
5617<p>Blur with the given radius, standard deviation (sigma), and angle. The
5618angle given is the angle toward which the image is blurred. That is the
5619direction people would consider the object is coming from. </p>
5620
5621<p>Note that the blur is not uniform distribution, giving the motion a
5622definite sense of direction of movement. </p>
5623
5624<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5625pixels which are outside the image proper are blurred into the final result.
5626</p>
5627
5628<div style="margin: auto;">
5629 <h3 class="magick-header"><a id="name"></a>-name</h3>
5630</div>
5631
5632<p class="magick-description">name an image.</p>
5633<div style="margin: auto;">
5634 <h3 class="magick-header"><a id="negate"></a>-negate</h3>
5635</div>
5636
5637<p class="magick-description">replace each pixel with its complementary color.</p>
5638
5639<p>The red, green, and blue intensities of an image are negated. White becomes
5640black, yellow becomes blue, etc. Use <a href="command-line-options.html#negate">+negate</a> to only
5641negate the grayscale pixels of the image.</p>
5642
5643<div style="margin: auto;">
5644 <h3 class="magick-header"><a id="noise"></a>-noise <var>geometry</var><br>
5645 +noise <var>type</var></h3>
5646</div>
5647
5648<p class="magick-description">Add or reduce noise in an image.</p>
5649
5650<p>The principal function of noise peak elimination filter is to smooth the
5651objects within an image without losing edge information and without creating
5652undesired structures. The central idea of the algorithm is to replace a pixel
5653with its next neighbor in value within a pixel window, if this pixel has been
5654found to be noise. A pixel is defined as noise if and only if this pixel is
5655a maximum or minimum within the pixel window.</p>
5656
5657<p>Use <code><a href="command-line-options.html#noise">-noise</a> <var>radius</var></code> to
5658specify the width of the neighborhood when reducing noise. This is equivalent
5659to using a <code><a href="command-line-options.html#statistic">-statistic</a> NonPeak</code> operation,
5660which should be used in preference.</p>
5661
5662<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
5663types:</p>
5664
5665<pre>
5666Gaussian
5667Impulse
5668Laplacian
5669Multiplicative
5670Poisson
5671Random
5672Uniform
5673</pre>
5674
5675<p>The amount of noise added can be controlled by the <code><a href="command-line-options.html#attenuate">-attenuate</a></code> setting. If unset the value is
5676equivalent to 1.0, or a maximum noise addition.</p>
5677
5678<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>
5679
5680<p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
5681
5682<p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
5683the use of a controlling value to specify the amount of noise that should be
5684added to an image. </p>
5685
5686
5687<div style="margin: auto;">
5688 <h3 class="magick-header"><a id="normalize"></a>-normalize</h3>
5689</div>
5690
5691<p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
5692
5693<p>The intensity values are stretched to cover the entire range of possible
5694values. While doing so, black-out at most <var>2%</var> of the pixels and
5695white-out at most <var>1%</var> of the pixels.</p>
5696
5697<p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize">-normalize</a>
5698is equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x1%</a>.
5699(Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x99%</a>).</p>
5700
5701<p>All the channels are normalized in concert by the came amount so as to
5702preserve color integrity, when the default <a href="command-line-options.html#channel">+channel</a>
5703setting is in use. Specifying any other <a href="command-line-options.html#channel">-channel</a>
5704setting will normalize the RGB channels independently.</p>
5705
5706<p>See <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> for more details.
5707Also see <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect' normalization
5708that is better suited to mathematically generated images. </p>
5709
5710<p>This operator is under review for re-development. </p>
5711
5712
5713<div style="margin: auto;">
5714 <h3 class="magick-header"><a id="opaque"></a>-opaque <var>color</var></h3>
5715</div>
5716
5717<p class="magick-description">change this color to the fill color within the image.</p>
5718
5719<p>The <var>color</var> argument is defined using the format
5720described 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
5721given.</p>
5722
5723<p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
5724the target color. </p>
5725
5726<p>The <a href="command-line-options.html#transparent">-transparent</a> operator is exactly the same
5727as <a href="command-line-options.html#opaque">-opaque</a> but replaces the matching color with
5728transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
5729To ensure that it can do this it also ensures that the image has an alpha
5730channel enabled, as per "<code><a href="command-line-options.html#alpha">-alpha</a> set</code>", for
5731the 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>
5732
5733
5734<div style="margin: auto;">
5735 <h3 class="magick-header"><a id="ordered-dither"></a>-ordered-dither <var>threshold_map</var>{,<var>level</var>...}</h3>
5736</div>
5737
5738<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
5739given number of <var>levels</var> per color channel.</p>
5740
5741<p>You can choose from these standard threshold maps:</p>
5742
5743<pre class="pre-scrollable">
5744threshold 1x1 Threshold 1x1 (non-dither)
5745checks 2x1 Checkerboard 2x1 (dither)
5746o2x2 2x2 Ordered 2x2 (dispersed)
5747o3x3 3x3 Ordered 3x3 (dispersed)
5748o4x4 4x4 Ordered 4x4 (dispersed)
5749o8x8 8x8 Ordered 8x8 (dispersed)
5750h3x4a 4x1 Halftone 4x4 (angled)
5751h6x6a 6x1 Halftone 6x6 (angled)
5752h8x8a 8x1 Halftone 8x8 (angled)
5753h3x4o Halftone 4x4 (orthogonal)
5754h6x6o Halftone 6x6 (orthogonal)
5755h8x8o Halftone 8x8 (orthogonal)
5756h36x16o Halftone 16x16 (orthogonal)
5757c5x5b c5x5 Circles 5x5 (black)
5758c5x5w Circles 5x5 (white)
5759c6x6b c6x6 Circles 6x6 (black)
5760c6x6w Circles 6x6 (white)
5761c7x7b c7x7 Circles 7x7 (black)
5762c7x7w Circles 7x7 (white)
5763</pre>
5764
5765<p> The <code>threshold</code> generated a simple 50% threshold of the image.
5766This 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.
5767</p>
5768
5769<p>The <code>checks</code> pattern produces a 3 level checkerboard dither
5770pattern. That is a grayscale will become a pattern of solid black, solid
5771white, and mid-tone colors into a checkerboard pattern of black and white.
5772</p>
5773
5774<p>You can define your own <var>threshold map</var> for ordered
5775dithering and halftoning your images, in either personal or system
5776<code>thresholds.xml</code> XML file. See <a href="resources.html">Resources</a>
5777for more details of configuration files. </p>
5778
5779<p>To print a complete list of the thresholds that have been defined, use the
5780<a href="command-line-options.html#list">-list threshold</a> option.</p>
5781
5782<p>Note that at this time the same threshold dithering map is used for all
5783color channels, no attempt is made to offset or rotate the map for different
5784channels is made, to create an offset printing effect. Also as the maps are
5785simple threshold levels, the halftone and circle maps will create incomplete
5786circles along the edges of a colored area. Also all the effects are purely
5787on/off boolean effects, without anti-aliasing to make the circles smooth
5788looking. Large dots can be made to look better with a small amount of blurring
5789after being created. </p>
5790
5791
5792<div style="margin: auto;">
5793 <h3 class="magick-header"><a id="orient"></a>-orient <var>image orientation</var></h3>
5794</div>
5795
5796<p class="magick-description">specify orientation of a digital camera image.</p>
5797
5798<p>Choose from these orientations:</p>
5799
5800<pre>
5801bottom-left right-top
5802bottom-right top-left
5803left-bottom top-right
5804left-top undefined
5805right-bottom
5806</pre>
5807
5808<p>To print a complete list of orientations, use the <a href="command-line-options.html#list">-list
5809orientation</a> option.</p>
5810
5811
5812<div style="margin: auto;">
5813 <h3 class="magick-header"><a id="page"></a>-page <var>geometry</var><br>
5814 -page <var>media</var>[<var>offset</var>][{<var>^!&lt;&gt;</var>}]<br>
5815 +page
5816 </h3>
5817</div>
5818
5819<p class="magick-description">Set the size and location of an image on the larger virtual canvas.</p>
5820
5821<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5822
5823<p>For convenience you can specify the page size using <var>media</var> (see below). Offsets can then be added as with other
5824<var>geometry</var> arguments (e.g. <a href="command-line-options.html#page">-page</a> <code>Letter+43+43</code>).</p>
5825
5826<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.
5827The choices for a PostScript page are:</p>
5828
5829<dl class="dl-horizontal">
5830<dt> 11x17 </dt> <dd> 792 x 1224</dd>
5831<dt> Ledger </dt> <dd> 1224 x 792</dd>
5832<dt> Legal </dt> <dd> 612 x 1008</dd>
5833<dt> Letter </dt> <dd> 612 x 792</dd>
5834<dt> LetterSmall</dt> <dd> 612 x 792</dd>
5835<dt> ArchE </dt> <dd> 2592 x 3456</dd>
5836<dt> ArchD </dt> <dd> 1728 x 2592</dd>
5837<dt> ArchC </dt> <dd> 1296 x 1728</dd>
5838<dt> ArchB </dt> <dd> 864 x 1296</dd>
5839<dt> ArchA </dt> <dd> 648 x 864</dd>
5840<dt> A0 </dt> <dd> 2380 x 3368</dd>
5841<dt> A1 </dt> <dd> 1684 x 2380</dd>
5842<dt> A2 </dt> <dd> 1190 x 1684</dd>
5843<dt> A3 </dt> <dd> 842 x 1190</dd>
5844<dt> A4 </dt> <dd> 595 x 842</dd>
5845<dt> A4Small </dt> <dd> 595 x 842</dd>
5846<dt> A5 </dt> <dd> 421 x 595</dd>
5847<dt> A6 </dt> <dd> 297 x 421</dd>
5848<dt> A7 </dt> <dd> 210 x 297</dd>
5849<dt> A8 </dt> <dd> 148 x 210</dd>
5850<dt> A9 </dt> <dd> 105 x 148</dd>
5851<dt> A10 </dt> <dd> 74 x 105</dd>
5852<dt> B0 </dt> <dd> 2836 x 4008</dd>
5853<dt> B1 </dt> <dd> 2004 x 2836</dd>
5854<dt> B2 </dt> <dd> 1418 x 2004</dd>
5855<dt> B3 </dt> <dd> 1002 x 1418</dd>
5856<dt> B4 </dt> <dd> 709 x 1002</dd>
5857<dt> B5 </dt> <dd> 501 x 709</dd>
5858<dt> C0 </dt> <dd> 2600 x 3677</dd>
5859<dt> C1 </dt> <dd> 1837 x 2600</dd>
5860<dt> C2 </dt> <dd> 1298 x 1837</dd>
5861<dt> C3 </dt> <dd> 918 x 1298</dd>
5862<dt> C4 </dt> <dd> 649 x 918</dd>
5863<dt> C5 </dt> <dd> 459 x 649</dd>
5864<dt> C6 </dt> <dd> 323 x 459</dd>
5865<dt> Flsa </dt> <dd> 612 x 936</dd>
5866<dt> Flse </dt> <dd> 612 x 936</dd>
5867<dt> HalfLetter </dt> <dd> 396 x 612</dd>
5868</dl>
5869
5870<p>This option is also used to place subimages when writing to a multi-image
5871format that supports offsets, such as GIF89 and MNG. When used for this
5872purpose the offsets are always measured from the top left corner of the canvas
5873and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
5874position 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
5875file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
5876the sequence with nonzero width and height defines the width and height values
5877that are written in the <code>MHDR</code> chunk. Otherwise, the MNG width and
5878height are computed from the bounding box that contains all images in the
5879sequence. When writing a GIF89 file, only the bounding box method is used to
5880determine its dimensions.</p>
5881
5882<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
5883left-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
5884page. If the image size exceeds the PostScript page, it is reduced to fit the
5885page. 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
5886corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
5887present with a value other than <var>NorthWest</var>.</p>
5888
5889<p>The default page dimensions for a TEXT image is 612x792.</p>
5890
5891<p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
5892
5893<p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
5894
5895<div style="margin: auto;">
5896 <h3 class="magick-header"><a id="paint"></a>-paint <var>radius</var></h3>
5897</div>
5898
5899<p class="magick-description">simulate an oil painting.</p>
5900
5901<p>Each pixel is replaced by the most frequent color in a circular
5902neighborhood whose width is specified with <var>radius</var>.</p>
5903
5904<div style="margin: auto;">
5905 <h3 class="magick-header"><a id="path"></a>-path <var>path</var></h3></div>
5906
5907<p class="magick-description">write images to this path on disk.</p>
5908
5909<div style="margin: auto;">
5910 <h3 class="magick-header"><a id="pause_animate_"></a>-pause <var>seconds</var></h3>
5911</div>
5912
5913<p class="magick-description">Pause between animation loops</p>
5914
5915<p>Pause for the specified number of seconds before repeating the animation.</p>
5916
5917<div style="margin: auto;">
5918 <h3 class="magick-header"><a id="pause_import_"></a>-pause <var>seconds</var></h3>
5919</div>
5920
5921<p class="magick-description">Pause between snapshots.</p>
5922
5923<p>Pause for the specified number of seconds before taking the next snapshot.</p>
5924
5925<div style="margin: auto;">
5926 <h3 class="magick-header"><a id="perceptible"></a>-perceptible <var>epsilon</var></h3>
5927</div>
5928
5929<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>
5930
5931<div style="margin: auto;">
5932 <h3 class="magick-header"><a id="ping"></a>-ping</h3>
5933</div>
5934
5935<p class="magick-description">efficiently determine image characteristics.</p>
5936
5937<div style="margin: auto;">
5938 <h3 class="magick-header"><a id="pointsize"></a>-pointsize <var>value</var></h3>
5939</div>
5940
5941<p class="magick-description">pointsize of the PostScript, OPTION1, or TrueType font.</p>
5942
5943<div style="margin: auto;">
5944 <h3 class="magick-header"><a id="polaroid"></a>-polaroid <var>angle</var></h3>
5945</div>
5946
5947<p class="magick-description">simulate a Polaroid picture.</p>
5948
5949<p>Use <code>+polaroid</code> to rotate the image at a random angle between -15 and +15 degrees.</p>
5950
5951<div style="margin: auto;">
5952 <h3 class="magick-header"><a id="poly"></a>-poly <var>"wt,exp ..."</var></h3>
5953</div>
5954
5955<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>
5956
5957<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>
5958
5959<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>
5960
5961<p>The format is: <var>output = wt1*image1^exp1 + wt2*image2^exp2 </var>...</p>
5962
5963<p>Some simple uses are:</p>
5964<ul>
5965<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>
5966<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>
5967</ul>
5968
5969<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>
5970
5971<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>
5972
5973
5974<div style="margin: auto;">
5975 <h3 class="magick-header"><a id="posterize"></a>-posterize <var>levels</var></h3>
5976</div>
5977
5978<p class="magick-description">reduce the image to a limited number of color levels per channel.</p>
5979
5980<p>Very low values of <var>levels</var>, e.g., 2, 3, 4, have the most
5981visible effect.</p>
5982
5983<div style="margin: auto;">
5984 <h3 class="magick-header"><a id="precision"></a>-precision <var>value</var></h3>
5985</div>
5986
5987<p class="magick-description">set the maximum number of significant digits to be printed.</p>
5988
5989<div style="margin: auto;">
5990 <h3 class="magick-header"><a id="preview"></a>-preview <var>type</var></h3>
5991</div>
5992
5993<p class="magick-description">image preview type.</p>
5994
5995<p>Use this option to affect the preview operation of an image (e.g.
5996<code>convert file.png -preview Gamma Preview:gamma.png</code>). Choose from
5997these previews:</p>
5998
5999<pre class="pre-scrollable">
6000AddNoise
6001Blur
6002Brightness
6003Charcoal
6004Despeckle
6005Dull
6006EdgeDetect
6007Gamma
6008Grayscale
6009Hue
6010Implode
6011JPEG
6012OilPaint
6013Quantize
6014Raise
6015ReduceNoise
6016Roll
6017Rotate
6018Saturation
6019Segment
6020Shade
6021Sharpen
6022Shear
6023Solarize
6024Spiff
6025Spread
6026Swirl
6027Threshold
6028Wave
6029</pre>
6030
6031<p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
6032
6033<p>The default preview is <code>JPEG</code>.</p>
6034
6035<div style="margin: auto;">
6036 <h3 class="magick-header"><a id="print"></a>-print <var>string</var></h3>
6037</div>
6038
6039<p class="magick-description">interpret string and print to console.</p>
6040
6041<div style="margin: auto;">
6042 <h3 class="magick-header"><a id="process"></a>-process <var>command</var></h3>
6043</div>
6044
6045<p class="magick-description">process the image with a custom image filter.</p>
6046
6047<p>The command arguments has the form <code>"module arg1 arg2 arg3 ...
6048argN"</code> where <code>module</code> is the name of the module to invoke (e.g.
6049"Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
6050pass to the process module.</p>
6051
6052<div style="margin: auto;">
6053 <h3 class="magick-header"><a id="profile"></a>-profile <var>filename</var><br>
6054 +profile <var>profile_name</var></h3>
6055</div>
6056
6057<p class="magick-description">Manage ICM, IPTC, or generic profiles in an image.</p>
6058
6059<p>Using <a href="command-line-options.html#profile">-profile</a> <var>filename</var> adds an
6060ICM (ICC color management), IPTC (newswire information), or a generic profile
6061to the image.</p>
6062
6063<p>Use <a href="command-line-options.html#profile">+profile <var>profile_name</var></a> to
6064remove the indicated profile. ImageMagick uses standard filename globbing, so
6065wildcard expressions may be used to remove more than one profile. Here we
6066remove all profiles from the image except for the XMP profile: <code>+profile
6067"!xmp,*"</code>. </p>
6068
6069<p>Use <code>identify -verbose</code> to find out which profiles are in the
6070image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
6071comments).</p>
6072
6073<p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
6074used. Instead, simply write the file to an image format such as <var>APP1, 8BIM, ICM,</var> or <var>IPTC</var>.</p>
6075
6076<p>For example, to extract the Exif data (which is stored in JPEG files in the
6077<var>APP1</var> profile), use.</p>
6078
6079<pre>
6080convert cockatoo.jpg profile.exif
6081</pre>
6082
6083<p>It is important to note that results may depend on whether or not the
6084original 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
6085therefore a conversion is made each time it is encountered, in order, in the
6086command-line. For instance, in the following example, if the original image is
6087CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
6088
6089<pre>
6090convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff
6091</pre>
6092
6093<p>Furthermore, since ICC profiles are not necessarily symmetric, extra
6094conversion steps can yield unwanted results. CMYK profiles are often very
6095asymmetric since they involve 3−&gt;4 and 4−&gt;3 channel mapping.
6096</p>
6097
6098<div style="margin: auto;">
6099 <h3 class="magick-header"><a id="quality"></a>-quality <var>value</var></h3>
6100</div>
6101
6102<p class="magick-description">JPEG/MIFF/PNG compression level.</p>
6103
6104<p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
6105highest compression) to 100 (best quality but least effective compression).
6106The default is to use the estimated quality of your input image if it can
6107be determined, otherwise 92. When the quality is greater than 90, then the
6108chroma channels are not downsampled.
6109Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
6110factors for chroma downsampling.</p>
6111
6112<p>For the JPEG-2000 image format, quality is mapped using a non-linear
6113equation to the compression ratio required by the Jasper library. This
6114non-linear equation is intended to loosely approximate the quality provided by
6115the JPEG v1 format. The default quality value 100, a request for non-lossy
6116compression. A quality of 75 results in a request for 16:1 compression.</p>
6117
6118<p>For the MNG and PNG image formats, the quality value sets the zlib
6119compression level (quality / 10) and filter-type (quality % 10). The default
6120PNG "quality" is 75, which means compression level 7 with adaptive PNG
6121filtering, unless the image has a color map, in which case it means
6122compression level 7 with no PNG filtering.</p>
6123
6124<p>For compression level 0 (quality value less than 10), the Huffman-only
6125strategy is used, which is fastest but not necessarily the worst
6126compression.</p>
6127
6128<p>If filter-type is 4 or less, the specified PNG filter-type is used for
6129all scanlines:</p>
6130
6131<dl class="dl-horizontal">
6132<dt>0</dt><dd>none</dd>
6133<dt>1</dt><dd>sub</dd>
6134<dt>2</dt><dd>up</dd>
6135<dt>3</dt><dd>average</dd>
6136<dt>4</dt><dd>Paeth</dd>
6137</dl>
6138
6139<p>If filter-type is 5, adaptive filtering is used when quality is greater
6140than 50 and the image does not have a color map, otherwise no filtering is
6141used.</p>
6142
6143<p>If filter-type is 6, adaptive filtering
6144with <var>minimum-sum-of-absolute-values</var> is used.</p>
6145
6146<p>Only if the output is MNG, if filter-type is 7, the LOCO color
6147transformation (intrapixel differencing) and adaptive filtering
6148with <var>minimum-sum-of-absolute-values</var> are used.</p>
6149
6150<p>If the filter-type is 8 the zlib Z_RLE compression strategy (or the
6151Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6152adaptive PNG filtering.</p>
6153
6154<p>If the filter-type is 9 the zlib Z_RLE compression strategy (or the
6155Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
6156no PNG filtering.</p>
6157
6158<p>The quality setting has no effect on the appearance or signature of PNG
6159and MNG images, since the compression is always lossless.</p>
6160
6161<p>Not all combinations of compression level, strategy, and PNG filter type
6162can be obtained using the -quality option. For more precise control,
6163you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
6164PNG:compression-filter=N defines, respectively, instead.
6165See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
6166over values from the -quality option.</p>
6167
6168<p>For further information, see
6169the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
6170
6171<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>
6172
6173<p>For the BPG image format, quality/2 is the actual BPG compression level (range from 0 to 51).</p>
6174
6175<div style="margin: auto;">
6176 <h3 class="magick-header"><a id="quantize"></a>-quantize <var>colorspace</var></h3>
6177</div>
6178
6179<p class="magick-description">reduce colors using this colorspace.</p>
6180
6181<p>This setting defines the colorspace used to sort out and reduce the number
6182of 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
6183automatically when saving images to color-limited image file formats, such as
6184GIF, and PNG8.</p>
6185
6186
6187<div style="margin: auto;">
6188 <h3 class="magick-header"><a id="quiet"></a>-quiet</h3>
6189</div>
6190
6191<p class="magick-description">suppress all warning messages. Error messages are still reported.</p>
6192
6193<div style="margin: auto;">
6194 <h3 class="magick-header"><a id="radial-blur"></a>-radial-blur <var>angle</var></h3>
6195</div>
6196
6197<p class="magick-description">Blur around the center of the image.</p>
6198
6199<p>Note that this is actually a rotational blur rather than a radial and as
6200such actually mis-named. </p>
6201
6202<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
6203pixels which are outside the image proper are blurred into the final result.
6204</p>
6205
6206
6207<div style="margin: auto;">
6208 <h3 class="magick-header"><a id="raise"></a>-raise <var>thickness</var></h3>
6209</div>
6210
6211<p class="magick-description">Lighten or darken image edges.</p>
6212
6213<p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
6214a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>. </p>
6215
6216<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>
6217
6218<div style="margin: auto;">
6219 <h3 class="magick-header"><a id="random-threshold"></a>-random-threshold <var>low</var>x<var>high</var></h3>
6220</div>
6221
6222<p class="magick-description">Apply a random threshold to the image.</p>
6223
6224<div style="margin: auto;">
6225 <h3 class="magick-header"><a id="red-primary"></a>-red-primary <var>x,y</var></h3>
6226</div>
6227
6228<p class="magick-description">Set the red chromaticity primary point.</p>
6229
6230<div style="margin: auto;">
6231 <h3 class="magick-header"><a id="regard-warnings"></a>-regard-warnings</h3>
6232</div>
6233
6234<p class="magick-description">Pay attention to warning messages.</p>
6235
6236<p>This option causes some warnings in some image formats to be treated
6237as errors. </p>
6238
6239<div style="margin: auto;">
6240 <h3 class="magick-header"><a id="remap"></a>-remap <var>filename</var></h3>
6241</div>
6242
6243<p class="magick-description">Reduce the number of colors in an image to the colors used by this image.</p>
6244
6245<p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
6246the given colors are dithered over the image as necessary, otherwise the closest
6247color (in RGB colorspace) is selected to replace that pixel in the image. </p>
6248
6249<p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
6250images in the current image sequence, all the images will have the same color
6251table. That means that when saved to a file format such as GIF, it will use
6252that color table as a single common or global color table, for all the images,
6253without requiring extra local color tables. </p>
6254
6255<p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
6256sequence to use a common color map over all the images. This equivalent to
6257appending all the images together (without extra background colors) and color
6258reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
6259limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
6260images. This ensures all the images follow a single color map. </p>
6261
6262<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
6263no color changes are needed. In that case, its only effect is to force the use
6264of 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
6265reduce the number of colors in an animated image sequence. </p>
6266
6267<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>
6268
6269<div style="margin: auto;">
6270 <h3 class="magick-header"><a id="region"></a>-region <var>geometry</var></h3>
6271</div>
6272
6273<p class="magick-description">Set a region in which subsequent operations apply.</p>
6274
6275<p>The <var>x</var> and <var>y</var> offsets are treated
6276in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
6277
6278<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6279
6280<p>Use <code>+region</code> to remove any previously set regions.</p>
6281
6282
6283<div style="margin: auto;">
6284 <h3 class="magick-header"><a id="remote"></a>-remote</h3>
6285</div>
6286
6287<p class="magick-description">perform a remote operation.</p>
6288
6289<p>The only command recognized is the name of an image file to load.</p>
6290
6291<p>If you have more than one <a href="display.html">display</a> application
6292running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
6293specify which application to control.</p>
6294
6295<div style="margin: auto;">
6296 <h3 class="magick-header"><a id="render"></a>-render</h3>
6297</div>
6298
6299<p class="magick-description">render vector operations.</p>
6300
6301<p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
6302This useful when saving the result to vector formats such as MVG or SVG.</p>
6303
6304<div style="margin: auto;">
6305<h3 class="magick-header"><a id="repage"></a>-repage <var>geometry</var></h3>
6306</div>
6307
6308<p class="magick-description">Adjust the canvas and offset information of the image.</p>
6309
6310<p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
6311rather than a setting. You can separately set the canvas size or the offset
6312of the image on that canvas by only providing those components. </p>
6313
6314<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6315
6316<p>If a <code>!</code> flag is given the offset given is added to the existing
6317offset to move the image relative to its previous position. This useful for
6318animation sequences. </p>
6319
6320<p>A given a canvas size of zero such as '<code>0x0</code>' forces it to
6321recalculate the canvas size so the image (at its current offset) will appear
6322completely on that canvas (unless it has a negative offset).</p>
6323
6324<p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
6325canvas meta-data from the images. </p>
6326
6327<p>The <a href="command-line-options.html#set">-set</a> '<code>page</code>' option can be used to
6328directly assign virtual canvas meta-data. </p>
6329
6330
6331<div style="margin: auto;">
6332 <h3 class="magick-header"><a id="resample"></a>-resample <var>horizontal</var>x<var>vertical</var></h3>
6333</div>
6334
6335<p class="magick-description">Resample image to specified horizontal and vertical resolution.</p>
6336
6337<p>Resize the image so that its rendered size remains the same as the original
6338at the specified target resolution. For example, if a 300 DPI image renders at
63393 inches by 2 inches on a 300 DPI device, when the image has been resampled to
634072 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that
6341only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
6342storing the image resolution. For formats which do not support an image
6343resolution, 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
6344resample resolution.</p>
6345
6346<p>Note that Photoshop stores and obtains image resolution from a proprietary
6347embedded profile. If this profile exists in the image, then Photoshop will
6348continue to treat the image using its former resolution, ignoring the image
6349resolution specified in the standard file header.</p>
6350
6351<div style="margin: auto;">
6352 <h3 class="magick-header"><a id="resize"></a>-resize <var>geometry</var></h3>
6353</div>
6354
6355<p class="magick-description">Resize an image.</p>
6356
6357<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
6358ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
6359
6360<p>If the <a href="command-line-options.html#filter">-filter</a> option
6361or <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
6362filter.</p>
6363
6364<p>Many image processing algorithms assume your image is in a linear-light
6365coding. If your image is gamma-corrected, you can remove the nonlinear gamma
6366correction, apply the transform, then restore it like this:</p>
6367
6368<pre>
6369convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \
6370 -quality 92 passport.jpg
6371</pre>
6372
6373<div style="margin: auto;">
6374 <h3 class="magick-header"><a id="respect-parentheses"></a>-respect-parentheses</h3>
6375</div>
6376
6377<p class="magick-description">settings remain in effect until parenthesis boundary.</p>
6378
6379<div style="margin: auto;">
6380 <h3 class="magick-header"><a id="reverse"></a>-reverse</h3>
6381</div>
6382
6383<p class="magick-description">Reverse the order of images in the current image list.</p>
6384
6385
6386<div style="margin: auto;">
6387 <h3 class="magick-header"><a id="roll"></a>-roll {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
6388</div>
6389
6390<p class="magick-description">roll an image vertically or horizontally by the amount given.</p>
6391
6392<p>A negative <var>x</var> offset rolls the image right-to-left.
6393A negative <var>y</var> offset rolls the image bottom-to-top.</p>
6394
6395
6396<div style="margin: auto;">
6397 <h3 class="magick-header"><a id="rotate"></a>-rotate <var>degrees</var>{<var>&lt;</var>}{<var>&gt;</var>}</h3>
6398</div>
6399
6400<p class="magick-description">Apply Paeth image rotation (using shear operations) to the image.</p>
6401
6402<p>Use <code>&gt;</code> to rotate the image only if its width exceeds the
6403height. <code>&lt;</code> rotates the image <var>only</var> if its width is less
6404than the height. For example, if you specify <code>-rotate "-90&gt;"</code> and
6405the image size is 480x640, the image is not rotated. However, if the image is
6406640x480, it is rotated by -90 degrees. If you use <code>&gt;</code> or
6407<code>&lt;</code>, enclose it in quotation marks to prevent it from being
6408misinterpreted as a file redirection.</p>
6409
6410<p>Empty triangles in the corners, left over from rotating the image, are
6411filled with the <code>background</code> color. </p>
6412
6413<p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
6414'<code>ScaleRotateTranslate</code>' distort method. </p>
6415
6416
6417<div style="margin: auto;">
6418 <h3 class="magick-header"><a id="sample"></a>-sample <var>geometry</var></h3>
6419</div>
6420
6421<p class="magick-description">minify / magnify the image with pixel subsampling and pixel replication, respectively.</p>
6422
6423<p>Change the image size simply by directly sampling the pixels original
6424from the image. When magnifying, pixels are replicated in blocks. When
6425minifying, pixels are sub-sampled (i.e., some rows and columns are skipped
6426over). </p>
6427
6428<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6429a <a href="command-line-options.html#filter">-filter</a> setting of <code>point</code> (nearest
6430neighbor), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
6431avoids all the filter processing of the image. As such it completely ignores
6432the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6433
6434<p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
6435will be added to the resulting image, though some colors may disappear. </p>
6436
6437<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
6438ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
6439
6440
6441<p>The actual sampling point is the middle of the sub-region being sampled.
6442As such a single pixel sampling of an image will take the middle pixel, (or
6443top-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
6444this position some other location within each sub-region being sampled, as
6445a percentage offset.</p>
6446
6447<p>By default this value is '<code>50</code>' for the midpoint, but could be set
6448to '<code>0</code>' for top-left, '<code>100</code>' for bottom-right, or with
6449separate X and Y offsets such as '<code>0x50</code>' for left-middle edge of
6450sampling sub-region.</p>
6451
6452
6453<div style="margin: auto;">
6454 <h3 class="magick-header"><a id="sampling-factor"></a>-sampling-factor <var>horizontal-factor</var>x<var>vertical-factor</var></h3>
6455</div>
6456
6457<p class="magick-description">sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</p>
6458
6459<p>This option specifies the sampling factors to be used by the JPEG encoder
6460for chroma downsampling. If this option is omitted, the JPEG library will use
6461its own default values. When reading or writing the YUV format and when
6462writing 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
6463downsampling method.</p>
6464
6465<div style="margin: auto;">
6466 <h3 class="magick-header"><a id="scale"></a>-scale <var>geometry</var></h3>
6467</div>
6468
6469<p class="magick-description">minify / magnify the image with pixel block averaging and pixel replication, respectively.</p>
6470
6471<p>Change the image size simply by replacing pixels by averaging pixels
6472together when minifying, or replacing pixels when magnifying. </p>
6473
6474<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6475a <a href="command-line-options.html#filter">-filter</a> setting of <code>box</code>. Though it is a lot
6476faster, as it avoids all the filter processing of the image. As such it
6477completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6478
6479<p>If when shrinking (minifying) images the original image is some integer
6480multiple of the new image size, the number of pixels averaged together to
6481produce the new pixel color is the same across the whole image. This is
6482a special case known as 'binning' and is often used as a method of reducing
6483noise in image such as those generated by digital cameras, especially in low
6484light conditions. </p>
6485
6486
6487<div style="margin: auto;">
6488 <h3 class="magick-header"><a id="scene"></a>-scene <var>value</var></h3>
6489</div>
6490
6491<p class="magick-description">set scene number.</p>
6492
6493<p>This option sets the scene number of an image or the first image in an image sequence.</p>
6494
6495<div style="margin: auto;">
6496 <h3 class="magick-header"><a id="screen"></a>-screen</h3>
6497</div>
6498
6499<p class="magick-description">specify the screen to capture.</p>
6500
6501<p>This option indicates that the GetImage request used to obtain the image
6502should be done on the root window, rather than directly on the specified
6503window. In this way, you can obtain pieces of other windows that overlap the
6504specified window, and more importantly, you can capture menus or other popups
6505that are independent windows but appear over the specified window.</p>
6506
6507<div style="margin: auto;">
6508 <h3 class="magick-header"><a id="seed"></a>-seed</h3>
6509</div>
6510
6511<p class="magick-description">seed a new sequence of pseudo-random numbers</p>
6512
6513<div style="margin: auto;">
6514 <h3 class="magick-header"><a id="segment"></a>-segment <var>cluster-threshold</var>x<var>smoothing-threshold</var></h3>
6515</div>
6516
6517<p class="magick-description">segment the colors of an image.</p>
6518
6519<p>Segment an image by analyzing the histograms of the color components and
6520identifying units that are homogeneous with the fuzzy c-means technique. This
6521is part of the ImageMagick color quantization routines. </p>
6522
6523<p>Specify <var>cluster threshold</var> as the number of pixels in
6524each cluster that must exceed the cluster threshold to be considered valid.
6525<var>Smoothing threshold</var> eliminates noise in the second
6526derivative of the histogram. As the value is increased, you can expect
6527a smoother second derivative. The default is 1.5.</p>
6528
6529<p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6530of the color clusters is returned.</p>
6531
6532
6533<div style="margin: auto;">
6534 <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>
6535</div>
6536
6537<p class="magick-description">Selectively blur pixels within a contrast threshold.</p>
6538
6539<p>Blurs those pixels that are less than or equal to the threshold in
6540contrast. The threshold may be expressed as a fraction of <var>QuantumRange</var> or as a percentage.</p>
6541
6542<div style="margin: auto;">
6543 <h3 class="magick-header"><a id="separate"></a>-separate</h3>
6544</div>
6545
6546<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>
6547
6548<div style="margin: auto;">
6549 <h3 class="magick-header"><a id="sepia-tone"></a>-sepia-tone <var>threshold</var></h3>
6550</div>
6551
6552<p class="magick-description">simulate a sepia-toned photo.</p>
6553
6554<p>Specify <var>threshold</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6555
6556<p>This option applies a special effect to the image, similar to the effect
6557achieved 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
6558toning. A threshold of 80% is a good starting point for a reasonable
6559tone.</p>
6560
6561
6562
6563<div style="margin: auto;">
6564 <h3 class="magick-header"><a id="set"></a>-set <var>key value</var></h3>
6565 <h3 class="magick-header">+set <var>key</var></h3>
6566</div>
6567
6568<p class="magick-description">sets image attributes and properties for images in the current image sequence.</p>
6569
6570<p>This will assign (or modify) specific settings attached to all the images
6571in the current image sequence. Using the <a href="command-line-options.html#set">+set</a> form of the
6572option will either remove, or reset that setting to a default state, as
6573appropriate. </p>
6574
6575<p>For example, it will modify specific well known image meta-data
6576'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
6577assigned before the image is read in, by using a <var>key</var> of
6578the same name. </p>
6579
6580<p>If the given <var>key</var> does not match a specific known
6581'attribute ', such as shown above, the setting is stored as a a free form
6582'property' string. Such settings are listed in <a href="command-line-options.html#verbose">-verbose</a> information ("<code>info:</code>" output format) as "Properties".
6583</p>
6584
6585<p>This includes string 'properties' that are set by and assigned to images
6586using 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
6587a global 'artifact' which are automatically assigned (and any <a href="escape.html">Format Percent
6588Escapes</a> expanded) to images as they are read in. For example:</p>
6589
6590<pre>
6591-&gt; convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png
6592identify -format %c rose.png
6593Rose is a rose is a rose is a rose
6594</pre>
6595
6596<p>The set value can also make use of <a href="escape.html">Format and Print Image
6597Properties</a> in the defined value. For example:</p>
6598
6599<pre>
6600-&gt; convert rose: -set origsize '%wx%h' -resize 50% \
6601 -format 'Old size = %[origsize] New size = %wx%h' info:
6602Old size = 70x46 New size = 35x23
6603</pre>
6604
6605<p>Other well known 'properties' that are available include:
6606'<code>date:create</code>' and '<code>date:modify</code>' and
6607'<code>signature</code>'. </p>
6608
6609<p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6610the '<code>page</code>' attribute of an image for images already in memory (also
6611see <a href="command-line-options.html#repage">-page</a>). However it is designed to provide a finer
6612control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6613option will only provide a direct, unmodified assignment of '<code>page</code>'
6614attribute. </p>
6615
6616<p>This option can also associate a colorspace or profile with your image.
6617For example,</p>
6618
6619<pre>
6620convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd
6621</pre>
6622
6623<p>Some 'properties' must be defined in a specific way to be used. For
6624example only 'properties' prefixed with "<code>filename:</code>" can be used to
6625modify the output filename of an image. For example</p>
6626
6627<pre>
6628convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'
6629</pre>
6630
6631<p>If the setting value is prefixed with "<code>option:</code>" the setting will
6632be 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
6633can be used to pass 'attributes' and 'properties' of one specific image,
6634in a way that allows you to use them in a completely different image, even if
6635the original image has long since been modified or destroyed. For example: </p>
6636
6637<pre>
6638convert rose: -set option:rosesize '%wx%h' -delete 0 \
6639 label:'%[rosesize]' label_size_of_rose.gif"
6640</pre>
6641
6642<p>Note that <a href="escape.html">Format Percent Escapes</a> will only match
6643a 'artifact' if the given <var>key</var> does not match an existing
6644'attribute' or 'property'. </p>
6645
6646<p>You can set the attributes of the image registry by prefixing the value
6647with <code>registry:</code>.</p>
6648
6649<p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
6650previously-formatted ancillary chunks into the output PNG file, using
6651the commandline option as shown below or by setting the profile via a
6652programming interface:</p>
6653
6654<pre>
6655convert in.png -set profile PNG-chunk-x:&lt;filename&gt; out.png
6656</pre>
6657
6658<p>where <var>x</var> is a location flag and
6659<var>filename</var> is a file containing the chunk
6660name in the first 4 bytes, then a colon (":"), followed by the chunk data.
6661This encoder will compute the chunk length and CRC, so those must not
6662be included in the file.</p>
6663
6664<p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
6665or "e" (end, i.e., after IDAT). If you want to write multiple chunks
6666of the same type, then add a short unique string after the "x" to prevent
6667subsequent profiles from overwriting the preceding ones, e.g.,</p>
6668
6669
6670<pre>
6671convert in.png -set profile PNG-chunk-b01:file01 \
6672 -profile PNG-chunk-b02:file02 out.png
6673</pre>
6674
6675<div style="margin: auto;">
6676 <h3 class="magick-header"><a id="shade"></a>-shade <var>azimuth</var>x<var>elevation</var></h3>
6677</div>
6678
6679<p class="magick-description">shade the image using a distant light source.</p>
6680
6681<p>Specify <var>azimuth</var> and <var>elevation</var> as
6682the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
6683the shading results as a grayscale image.</p>
6684
6685<div style="margin: auto;">
6686 <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>
6687</div>
6688
6689<p class="magick-description">simulate an image shadow.</p>
6690
6691<div style="margin: auto;">
6692 <h3 class="magick-header"><a id="shared-memory"></a>-shared-memory</h3>
6693</div>
6694
6695<p class="magick-description">use shared memory.</p>
6696
6697<p>This option specifies whether the utility should attempt to use shared
6698memory for pixmaps. ImageMagick must be compiled with shared memory support,
6699and the display must support the <var>MIT-SHM</var> extension.
6700Otherwise, this option is ignored. The default is <code>True</code>.</p>
6701
6702<div style="margin: auto;">
6703 <h3 class="magick-header"><a id="sharpen"></a>-sharpen <var>radius</var><br>-sharpen <var>radius</var>x<var>sigma</var></h3>
6704</div>
6705
6706<p class="magick-description">sharpen the image.</p>
6707
6708<p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
6709
6710<div style="margin: auto;">
6711 <h3 class="magick-header"><a id="shave"></a>-shave <var>geometry</var></h3>
6712</div>
6713
6714<p class="magick-description">Shave pixels from the image edges.</p>
6715
6716<p>The <var>size</var> portion of the <var>geometry</var>
6717argument specifies the width of the region to be removed from both sides of
6718the image and the height of the regions to be removed from top and bottom.
6719Offsets are ignored.</p>
6720
6721<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6722
6723<div style="margin: auto;">
6724 <h3 class="magick-header"><a id="shear"></a>-shear <var>Xdegrees</var>[x<var>Ydegrees</var>]</h3>
6725</div>
6726
6727<p class="magick-description">Shear the image along the x-axis and/or y-axis.</p>
6728
6729<p>The shear angles may be positive, negative, or zero. When <var>Ydegrees</var> is omitted it defaults to 0. When both angles are
6730given, the horizontal component of the shear is performed before the vertical
6731component.</p>
6732
6733<p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
6734horizontally or vertically, respectively),creating a parallelogram. The amount
6735of each is controlled by the respective shear angle. For horizontal shears,
6736<var>Xdegrees</var> is measured clockwise relative to "up" (the
6737negative 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
6738positive 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>
6739
6740<p>Empty triangles left over from shearing the image are filled with the color
6741defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
6742using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6743
6744<p>The horizontal shear is performed before the vertical part. This is
6745important to note, since horizontal and vertical shears do not
6746<var>commute</var>, i.e., the order matters in a sequence of shears. For
6747example, the following two commands are not equivalent.</p>
6748
6749<pre>
6750convert logo: -shear 20x0 -shear 0x60 logo-sheared.png
6751convert logo: -shear 0x60 -shear 20x0 logo-sheared.png
6752</pre>
6753
6754<p>The first of the two commands above is equivalent to the following, except
6755for the amount of empty space created; the command that follows generates
6756a smaller image, and so is a better choice in terms of time and space.</p>
6757
6758<pre>
6759convert logo: -shear 20x60 logo-sheared.png
6760</pre>
6761
6762<div style="margin: auto;">
6763 <h3 class="magick-header"><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <var>contrast</var>x<var>mid-point</var></h3>
6764</div>
6765
6766<p class="magick-description">increase the contrast without saturating highlights or shadows.</p>
6767
6768<p>Increase the contrast of the image using a sigmoidal transfer function
6769without saturating highlights or shadows. <var>Contrast</var>
6770indicates how much to increase the contrast. For example, 0 is none, 3 is
6771typical and 20 is a lot.
6772</p>
6773
6774<p>The <var>mid-point</var> indicates where the maximum change
6775'slope' in contrast should fall in the resultant image (0 is white; 50% is
6776middle-gray; 100% is black). </p>
6777
6778<p>By default the image contrast is increased, use <var>+sigmoidal-contrast</var> to decrease the contrast.</p>
6779
6780<p>To achieve the equivalent of a sigmoidal brightness change (similar to
6781a gamma adjustment), you would use <var>-sigmoidal-contrast
6782{brightness}x0%</var> to increase brightness and <var>+sigmoidal-contrast {brightness}x0%</var> to decrease brightness.
6783Note the use of '0' fo rthe mid-point of the sigmoidal curve. </p>
6784
6785<p>Using a very high <var>contrast</var> will produce a sort of
6786'smoothed thresholding' of the image. Not as sharp (with high aliasing
6787effects) of a true threshold, but with tapered gray-levels around the threshold
6788<var>mid-point</var>. </p>
6789
6790<div style="margin: auto;">
6791 <h3 class="magick-header"><a id="silent"></a>-silent</h3>
6792</div>
6793
6794<p class="magick-description">operate silently.</p>
6795
6796<div style="margin: auto;">
6797 <h3 class="magick-header"><a id="similarity-threshold"></a>-similarity-threshold <var>value</var></h3>
6798</div>
6799
6800<p class="magick-description">minimum RMSE for subimage match.</p>
6801
6802<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>
6803
6804<div style="margin: auto;">
6805 <h3 class="magick-header"><a id="size"></a>-size <var>width</var>[x<var>height</var>][<var>+offset</var>]</h3>
6806</div>
6807
6808<p class="magick-description">set the width and height of the image.</p>
6809
6810<p>Use this option to specify the width and height of raw images whose
6811dimensions are unknown such as <code>GRAY</code>, <code>RGB</code>, or
6812<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
6813image or tell the number of colors in a <code>MAP</code> image file, (e.g. -size
6814640x512+256).</p>
6815
6816<p>For Photo CD images, choose from these sizes:</p>
6817
6818<pre>
6819192x128
6820384x256
6821768x512
68221536x1024
68233072x2048
6824</pre>
6825
6826<div style="margin: auto;">
6827 <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>
6828</div>
6829
6830<p class="magick-description">simulate a pencil sketch.</p>
6831
6832<p>Sketch with the given radius, standard deviation (sigma), and angle. The
6833angle given is the angle toward which the image is sketched. That is the
6834direction people would consider the object is coming from. </p>
6835
6836<div style="margin: auto;">
6837 <h3 class="magick-header"><a id="smush"></a>-smush <var>offset</var></h3>
6838</div>
6839
6840<p class="magick-description">smush an image sequence together.</p>
6841
6842<div style="margin: auto;">
6843 <h3 class="magick-header"><a id="snaps"></a>-snaps <var>value</var></h3>
6844</div>
6845
6846<p class="magick-description">Set the number of screen snapshots.</p>
6847
6848<p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
6849
6850<div style="margin: auto;">
6851 <h3 class="magick-header"><a id="solarize"></a>-solarize <var>threshold</var></h3>
6852</div>
6853
6854<p class="magick-description">negate all pixels above the threshold level.</p>
6855
6856<p>Specify <var>factor</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6857
6858<p>This option produces a <var>solarization</var> effect seen when
6859exposing a photographic film to light during the development process.</p>
6860
6861<div style="margin: auto;">
6862 <h3 class="magick-header"><a id="sparse-color"></a>-sparse-color <var>method</var> '<var>x</var>,<var>y</var> <var>color</var> ...'</h3>
6863</div>
6864
6865<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>
6866
6867
6868<dl class="dl-horizontal">
6869 <dt>barycentric</dt>
6870 <dd>three point triangle of color given 3 points.
6871 Giving only 2 points will form a linear gradient between those points.
6872 The gradient generated extends beyond the triangle created by those
6873 3 points. </dd>
6874 <dt>bilinear</dt>
6875 <dd>Like barycentric but for 4 points. Less than 4 points
6876 fall back to barycentric. </dd>
6877 <dt>voronoi</dt>
6878 <dd>Simply map each pixel to the to nearest color point
6879 given. The result are polygonal 'cells' of solid color. </dd>
6880 <dt>manhatten</dt>
6881 <dd>Like voronoi, but resulting polygonal 'cells' are mapped to a fixed coordinate system.</dd>
6882 <dt>shepards</dt>
6883 <dd>Colors points biased on the ratio of inverse distance
6884 squared. Generating spots of color in a sea of the average of
6885 colors. </dd>
6886 <dt>inverse</dt>
6887 <dd>Colors points biased on the ratio of inverse distance.
6888 This generates sharper points of color rather than rounded spots of
6889 '<code>shepards</code>' Generating spots of color in a sea of the
6890 average of colors. </dd>
6891</dl>
6892
6893<p>The points are placed according to the images location on the virtual
6894canvas (<a href="command-line-options.html#page">-page</a> or <a href="command-line-options.html#repage">-repage</a>
6895offset), and do not actually have to exist on the given image, but may be
6896some point beyond the edge of the image. All points are floating point values.
6897</p>
6898
6899<p>Only the color channels defined by the <a href="command-line-options.html#channel">-channel</a> are
6900modified, which means that by default matte/alpha transparency channel is not
6901effected. Typically transparency channel is turned off either before or after
6902the operation. </p>
6903
6904<p>Of course if some color points are transparent to generate a transparent
6905gradient, then the image also requires transparency enabled to store the
6906values. </p>
6907
6908<p>All the above methods when given a single point of color will replace all
6909the colors in the image with the color given, regardless of the point. This is
6910logical, and provides an alternative technique to recolor an image to some
6911default value. </p>
6912
6913
6914<div style="margin: auto;">
6915 <h3 class="magick-header"><a id="splice"></a>-splice <var>geometry</var></h3>
6916</div>
6917
6918<p class="magick-description">Splice the current background color into the image.</p>
6919
6920<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
6921given <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
6922image into four quadrants, separating them by the inserted rows and columns.
6923</p>
6924
6925<p>If a dimension of geometry is zero no rows or columns will be added for that
6926dimension. 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
6927the 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>
6928
6929<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
6930added added all splices removed. </p>
6931
6932<div style="margin: auto;">
6933 <h3 class="magick-header"><a id="spread"></a>-spread <var>amount</var></h3>
6934</div>
6935
6936<p class="magick-description">displace image pixels by a random amount.</p>
6937
6938<p>The argument <var>amount</var> defines the size of the
6939neighborhood around each pixel from which to choose a candidate pixel to
6940blend.</p>
6941
6942<p>The lookup is controlled by the <a href="command-line-options.html#interpolate">-interpolate</a> setting.</p>
6943
6944<div style="margin: auto;">
6945 <h3 class="magick-header"><a id="statistic"></a>-statistic <var>type</var> <var>geometry</var></h3>
6946</div>
6947
6948<p class="magick-description">replace each pixel with corresponding statistic from the neighborhood.</p>
6949
6950<p>Choose from these statistic types:</p>
6951<dl class="dl-horizontal">
6952<dt>Gradient</dt><dd>maximum difference (max - min) value in neighborhood</dd>
6953<dt>Maximum</dt><dd>maximum value per channel in neighborhood</dd>
6954<dt>Minimum</dt><dd>minimum value per channel in neighborhood</dd>
6955<dt>Mean</dt><dd>average value per channel in neighborhood</dd>
6956<dt>Median</dt><dd>median value per channel in neighborhood</dd>
6957<dt>Mode</dt><dd>mode (most frequent) value per channel in neighborhood</dd>
6958<dt>Nonpeak</dt><dd>value just before or after the median value per channel in neighborhood</dd>
6959<dt>RMS</dt><dd>root mean square value per channel in neighborhood</dd>
6960<dt>StandardDeviation</dt><dd> standard deviation value per channel in neighborhood</dd>
6961</dl>
6962
6963<div style="margin: auto;">
6964 <h3 class="magick-header"><a id="stegano"></a>-stegano <var>offset</var></h3>
6965</div>
6966
6967<p class="magick-description">hide watermark within an image.</p>
6968
6969<p>Use an offset to start the image hiding some number of pixels from the
6970beginning of the image. Note this offset and the image size. You will need
6971this information to recover the steganographic image (e.g. display -size
6972320x256+35 stegano:image.png).</p>
6973
6974<div style="margin: auto;">
6975 <h3 class="magick-header"><a id="stereo"></a>-stereo <var>+x</var>{<var>+y</var>}</h3>
6976</div>
6977
6978<p class="magick-description">composite two images to create a red / cyan stereo anaglyph.</p>
6979
6980<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>
6981
6982<div style="margin: auto;">
6983 <h3 class="magick-header"><a id="storage-type"></a>-storage-type <var>type</var></h3>
6984</div>
6985
6986<p class="magick-description">pixel storage type. Here are the valid types:</p>
6987
6988<dl class="dl-horizontal">
6989<dt>char</dt><dd>unsigned characters</dd>
6990<dt>double</dt><dd>doubles</dd>
6991<dt>float</dt><dd>floats</dd>
6992<dt>integer</dt><dd>integers</dd>
6993<dt>long</dt><dd>longs</dd>
6994<dt>quantum</dt><dd>pixels in the native depth of your ImageMagick distribution</dd>
6995<dt>short</dt><dd>unsigned shorts</dd>
6996</dl>
6997
6998<p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
6999values range from 0 to the maximum value the storage type can support.</p>
7000
7001<div style="margin: auto;">
7002 <h3 class="magick-header"><a id="stretch"></a>-stretch <var>fontStretch</var></h3>
7003</div>
7004
7005<p class="magick-description">Set a type of stretch style for fonts.</p>
7006
7007<p>This setting suggests a type of stretch that ImageMagick should try to
7008apply to the currently selected font family. Select <var>fontStretch</var> from the following.</p>
7009
7010<pre>
7011Any
7012Condensed
7013Expanded
7014ExtraCondensed
7015ExtraExpanded
7016Normal
7017SemiCondensed
7018SemiExpanded
7019UltraCondensed
7020UltraExpanded
7021</pre>
7022
7023<p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
7024stretch</a>.</p>
7025
7026<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>
7027
7028<div style="margin: auto;">
7029 <h3 class="magick-header"><a id="strip"></a>-strip</h3>
7030</div>
7031
7032<p class="magick-description">strip the image of any profiles or comments.</p>
7033
7034<div style="margin: auto;">
7035 <h3 class="magick-header"><a id="stroke"></a>-stroke <var>color</var></h3>
7036</div>
7037
7038<p class="magick-description">color to use when stroking a graphic primitive.</p>
7039
7040<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7041
7042<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7043
7044<div style="margin: auto;">
7045 <h3 class="magick-header"><a id="strokewidth"></a>-strokewidth <var>value</var></h3>
7046</div>
7047
7048<p class="magick-description">set the stroke width.</p>
7049
7050<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7051
7052<div style="margin: auto;">
7053 <h3 class="magick-header"><a id="style"></a>-style <var>fontStyle</var></h3>
7054</div>
7055
7056<p class="magick-description">Set a font style for text.</p>
7057
7058<p>This setting suggests a font style that ImageMagick should try to apply to
7059the currently selected font family. Select <var>fontStyle</var> from
7060the following.</p>
7061
7062<pre>
7063Any
7064Italic
7065Normal
7066Oblique
7067</pre>
7068
7069<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>
7070
7071<div style="margin: auto;">
7072 <h3 class="magick-header"><a id="subimage-search"></a>-subimage-search</h3>
7073</div>
7074
7075<p class="magick-description">search for subimage.</p>
7076
7077<p>This option is required to have compare search for the best match location
7078of a small image within a larger image. This search will produce two images
7079(or two frames). The first is the "difference" image and the second will
7080be the "match score" image.</p>
7081
7082<p>The "match-score" image is smaller containing a pixel for ever possible
7083position of the top-left corner of the given sub-image. that is its size will
7084be the size of the larger_image - sub_image + 1. The brightest location in
7085this image is the location s the locate on the best match that is also
7086reported. Note that this may or may not be a perfect match, and the actual
7087brightness will reflect this. Other bright 'peaks' can be used to locate other
7088possible matching locations. </p>
7089
7090<p>Note that the search will try to compare the sub-image at every possible
7091location in the larger image, as such it can be very slow. The smaller the
7092sub-image the faster this search is. </p>
7093
7094
7095<div style="margin: auto;">
7096 <h3 class="magick-header"><a id="swap"></a>-swap <var>index,index</var></h3>
7097</div>
7098
7099<p class="magick-description">Swap the positions of two images in the image sequence.</p>
7100
7101<p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
7102images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
7103the last two images in the sequence.</p>
7104
7105<div style="margin: auto;">
7106 <h3 class="magick-header"><a id="swirl"></a>-swirl <var>degrees</var></h3>
7107</div>
7108
7109<p class="magick-description">swirl image pixels about the center.</p>
7110
7111<p><var>Degrees</var> defines the tightness of the swirl.</p>
7112
7113<div style="margin: auto;">
7114 <h3 class="magick-header"><a id="synchronize"></a>-synchronize</h3>
7115</div>
7116
7117<p class="magick-description">synchronize image to storage device.</p>
7118
7119<p>Set to "true" to ensure all image data is fully flushed and synchronized
7120to disk. There is a performance penalty, but the benefits include ensuring a
7121valid image file in the event of a system crash and early reporting if there
7122is not enough disk space for the image pixel cache.</p>
7123
7124<div style="margin: auto;">
7125 <h3 class="magick-header"><a id="taint"></a>-taint</h3>
7126</div>
7127
7128<p class="magick-description">Mark the image as modified.</p>
7129
7130<div style="margin: auto;">
7131 <h3 class="magick-header"><a id="text-font"></a>-text-font <var>name</var></h3>
7132</div>
7133
7134<p class="magick-description">font for writing fixed-width text.</p>
7135
7136<p>Specifies the name of the preferred font to use in fixed (typewriter style)
7137formatted text. The default is 14 point <var>Courier</var>.</p>
7138
7139<p>You can tag a font to specify whether it is a PostScript, TrueType, or
7140OPTION1 font. For example, <code>Courier.ttf</code> is a TrueType font and
7141<code>x:fixed</code> is OPTION1.</p>
7142
7143<div style="margin: auto;">
7144 <h3 class="magick-header"><a id="texture"></a>-texture <var>filename</var></h3>
7145</div>
7146
7147<p class="magick-description">name of texture to tile onto the image background.</p>
7148
7149<div style="margin: auto;">
7150 <h3 class="magick-header"><a id="threshold"></a>-threshold <var>value</var>{<var>%</var>}</h3>
7151</div>
7152
7153<!-- {<var>green,blue,opacity</var>}
7154<p>If the green or blue value is omitted, these channels use the same value as
7155the first one provided. If all three color values are the same, the result is
7156a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
7157and any partially transparent pixel becomes fully transparent.</p>
7158-->
7159
7160<p class="magick-description">Apply simultaneous black/white threshold to the image.</p>
7161
7162<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
7163maximum channel value, while all other values are assigned the minimum.</p>
7164
7165<p> The threshold value can be given as a percentage or as an absolute integer
7166value corresponding to the desired channel value. When given as an integer,
7167the minimum attainable value is 0 (corresponding to black when all channels
7168are affected), but the maximum value (corresponding to white) is that of the
7169<code>quantum depth</code> of the particular build of ImageMagick, and is
7170therefore dependent on the installation. For that reason, a reasonable
7171recommendation for most applications is to specify the threshold values as
7172a percentage. </p>
7173
7174<p> The following would force pixels with red values above 50% to have 100%
7175red values, while those at or below 50% red would be set to 0 in the red
7176channel. The green, blue, and alpha channels (if present) would be unchanged.
7177</p>
7178
7179<pre>
7180convert in.png -channel red -threshold 50% out.png
7181</pre>
7182
7183<p>As (possibly) impractical but instructive examples, the following would
7184generate an all-black and an all-white image with the same dimensions as the
7185input image.</p>
7186
7187
7188<pre>
7189convert in.png -threshold 100% black.png
7190convert in.png -threshold -1 white.png
7191</pre>
7192
7193<p>Note that the values of the transparency channel is treated as 'matte'
7194values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
7195
7196<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>.
7197</p>
7198
7199<div style="margin: auto;">
7200 <h3 class="magick-header"><a id="thumbnail"></a>-thumbnail <var>geometry</var></h3>
7201</div>
7202
7203<p class="magick-description">Create a thumbnail of the image.</p>
7204
7205<p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
7206for speed and any image profile, other than a color profile, is removed to
7207reduce 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>
7208
7209<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7210
7211<div style="margin: auto;">
7212 <h3 class="magick-header"><a id="tile"></a>-tile <var>filename</var></h3>
7213</div>
7214
7215<p class="magick-description">Set the tile image used for filling a subsequent graphic primitive.</p>
7216
7217<div style="margin: auto;">
7218 <h3 class="magick-header">-tile <var>geometry</var></h3>
7219</div>
7220
7221<p class="magick-description">Specify the layout of images.</p>
7222
7223<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7224
7225<div style="margin: auto;">
7226 <h3 class="magick-header">-tile</h3>
7227</div>
7228
7229<p class="magick-description">Specifies that a subsequent composite operation is repeated across and down image.</p>
7230
7231<div style="margin: auto;">
7232 <h3 class="magick-header"><a id="tile-offset"></a>-tile-offset {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h3>
7233</div>
7234
7235<p class="magick-description">Specify the offset for tile images, relative to the background image it is tiled on.</p>
7236
7237<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
7238creating a tiled canvas using <code>TILE:</code> or <code>PATTERN:</code> input
7239formats. </p>
7240
7241<p>Internally ImageMagick does a <a href="command-line-options.html#roll">-roll</a> of the tile image
7242by the arguments given when the tile image is set. </p>
7243
7244<div style="margin: auto;">
7245 <h3 class="magick-header"><a id="tint"></a>-tint <var>value</var></h3>
7246</div>
7247
7248<p class="magick-description">Tint the image with the fill color.</p>
7249
7250<p>Tint the image with the fill color.</p>
7251
7252<p>Specify the amount of tinting as a percentage. Pure colors like black,
7253white red, yellow, will not be affected by -tint. Only mid-range colors such
7254as the various shades of grey.</p>
7255
7256<div style="margin: auto;">
7257 <h3 class="magick-header"><a id="title"></a>-title <var>string</var></h3>
7258</div>
7259
7260<p class="magick-description">Assign a title to displayed image.", "animate", "display", "montage</p>
7261
7262<p>Use this option to assign a specific title to the image. This assigned to
7263the image window and is typically displayed in the window title bar.
7264Optionally you can include the image filename, type, width, height, Exif data,
7265or other image attribute by embedding special format characters described
7266under the <a href="command-line-options.html#format">-format</a> option.</p>
7267
7268<p>For example,</p>
7269
7270<pre>
7271-title "%m:%f %wx%h"
7272</pre>
7273
7274<p>produces an image title of <code>MIFF:bird.miff 512x480</code> for an image
7275titled <code>bird.miff</code> and whose width is 512 and height is 480.</p>
7276
7277
7278<div style="margin: auto;">
7279 <h3 class="magick-header"><a id="transform"></a>-transform</h3>
7280</div>
7281
7282<p class="magick-description">transform the image.</p>
7283
7284<p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
7285
7286<pre>
7287convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg
7288</pre>
7289
7290
7291<p>This operator has been now been superseded by the <a href="command-line-options.html#distort">-distort</a> '<code>AffineProjection</code>' method. </p>
7292
7293
7294<div style="margin: auto;">
7295 <h3 class="magick-header"><a id="transparent"></a>-transparent <var>color</var></h3>
7296</div>
7297
7298<p class="magick-description">Make this color transparent within the image.</p>
7299
7300<p>The <var>color</var> argument is defined using the format
7301described 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
7302given. </p>
7303
7304<p>Use <a href="command-line-options.html#transparent">+transparent</a> to invert the pixels matched.
7305that is make all non-matching colors transparent. </p>
7306
7307<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
7308current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
7309However the <a href="command-line-options.html#transparent">-transparent</a> operator also ensures
7310that 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>
7311
7312<p>Note that this does not define the color as being the 'transparency color'
7313used for color-mapped image formats, such as GIF. For that use <a href="command-line-options.html#transparent-color">-transparent-color</a> </p>
7314
7315
7316<div style="margin: auto;">
7317 <h3 class="magick-header"><a id="transparent-color"></a>-transparent-color <var>color</var></h3>
7318</div>
7319
7320<p class="magick-description">Set the transparent color.</p>
7321
7322<p>Sometimes this is used for saving to image formats such as
7323GIF and PNG8 which uses this color to represent boolean transparency. This
7324does not make a color transparent, it only defines what color the transparent
7325color 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>
7326
7327<p>This option allows you to have both an opaque visible color, as well as a
7328transparent color of the same color value without conflict. That is, you can
7329use the same color for both the transparent and opaque color areas within an
7330image. This, in turn, frees to you to select a transparent color that is
7331appropriate when an image is displayed by an application that does not handle a
7332transparent color index, while allowing ImageMagick to correctly handle images of this
7333type. </p>
7334
7335<p>The default transparent color is <code>#00000000</code>, which is fully transparent black.</p>
7336
7337<div style="margin: auto;">
7338 <h3 class="magick-header"><a id="transpose"></a>-transpose</h3>
7339</div>
7340
7341<p class="magick-description">Mirror the image along the top-left to bottom-right diagonal.</p>
7342
7343<p> This option mathematically transposes the pixel array. It is equivalent to the sequence <code>-flip -rotate 90</code>.
7344</p>
7345
7346<div style="margin: auto;">
7347 <h3 class="magick-header"><a id="transverse"></a>-transverse</h3>
7348</div>
7349
7350<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>
7351
7352
7353<div style="margin: auto;">
7354 <h3 class="magick-header"><a id="treedepth"></a>-treedepth <var>value</var></h3>
7355</div>
7356
7357<p class="magick-description">tree depth for the color reduction algorithm.</p>
7358
7359<p>Normally, this integer value is zero or one. A value of zero or one causes
7360the use of an optimal tree depth for the color reduction algorithm.</p>
7361
7362<p>An optimal depth generally allows the best representation of the source
7363image with the fastest computational speed and the least amount of memory.
7364However, the default depth is inappropriate for some images. To assure the
7365best representation, try values between 2 and 8 for this parameter. Refer to
7366the <a href="quantize.html">color reduction algorithm</a> for more details.</p>
7367
7368<p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
7369option, or writing to an image format which requires color reduction, is
7370required for this option to take effect.</p>
7371
7372<div style="margin: auto;">
7373 <h3 class="magick-header"><a id="trim"></a>-trim</h3>
7374</div>
7375
7376<p class="magick-description">trim an image.</p>
7377
7378<p>This option removes any edges that are exactly the same color as the corner
7379pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
7380edges that are nearly the same color as the corner pixels.</p>
7381
7382<p>The page or virtual canvas information of the image is preserved allowing
7383you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
7384image. Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
7385information if it is unwanted.</p>
7386
7387<p>If the trimmed image 'disappears' an warning is produced, and a special
7388single pixel transparent 'missed' image is returned, in the same way as when a
7389<a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
7390
7391
7392<div style="margin: auto;">
7393 <h3 class="magick-header"><a id="type"></a>-type <var>type</var></h3>
7394</div>
7395
7396<p class="magick-description">the image type.</p> <p>Choose from: <code>Bilevel</code>,
7397<code>Grayscale</code>, <code>GrayscaleMatte</code>, <code>Palette</code>,
7398<code>PaletteMatte</code>, <code>TrueColor</code>, <code>TrueColorMatte</code>,
7399<code>ColorSeparation</code>, or <code>ColorSeparationMatte</code>.</p>
7400
7401<p>Normally, when a format supports different subformats such as grayscale and
7402truecolor, 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
7403example, to prevent a JPEG from being written in grayscale format even though
7404only gray pixels are present, use.</p>
7405
7406<pre>
7407convert bird.png -type TrueColor bird.jpg
7408</pre>
7409
7410<p>Similarly, use <a href="command-line-options.html#type">-type TrueColorMatte</a> to force the
7411encoder to write an alpha channel even though the image is opaque, if the
7412output format supports transparency.</p>
7413
7414<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>
7415
7416<div style="margin: auto;">
7417 <h3 class="magick-header"><a id="undercolor"></a>-undercolor <var>color</var></h3>
7418</div>
7419
7420<p class="magick-description">set the color of the annotation bounding box.</p>
7421
7422<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7423
7424<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7425
7426
7427<div style="margin: auto;">
7428 <h3 class="magick-header"><a id="update"></a>-update <var>seconds</var></h3>
7429</div>
7430
7431<p class="magick-description">detect when image file is modified and redisplay.</p>
7432
7433<p>Suppose that while you are displaying an image the file that is currently
7434displayed is over-written. <code>display</code> will automagically detect that
7435the input file has been changed and update the displayed image
7436accordingly.</p>
7437
7438
7439<div style="margin: auto;">
7440 <h3 class="magick-header"><a id="unique-colors"></a>-unique-colors</h3>
7441</div>
7442
7443<p class="magick-description">discard all but one of any pixel color.</p>
7444
7445
7446<div style="margin: auto;">
7447 <h3 class="magick-header"><a id="units"></a>-units <var>type</var></h3>
7448</div>
7449
7450<p class="magick-description">the units of image resolution.</p>
7451
7452<p>Choose from: <code>Undefined</code>, <code>PixelsPerInch</code>, or
7453<code>PixelsPerCentimeter</code>. This option is normally used in conjunction
7454with the <a href="command-line-options.html#density">-density</a> option.</p>
7455
7456
7457<div style="margin: auto;">
7458 <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>
7459</div>
7460
7461<p class="magick-description">sharpen the image with an unsharp mask operator.</p>
7462
7463<p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
7464convolved with a Gaussian operator of the given radius and standard deviation
7465(sigma). For reasonable results, radius should be larger than sigma. Use
7466a radius of 0 to have the method select a suitable radius.</p>
7467
7468<p>The parameters are:</p>
7469
7470<dl class="dl-horizontal">
7471<dt>radius</dt>
7472<dd>The radius of the Gaussian, in pixels, not counting the center pixel (default 0).</dd>
7473<dt>sigma</dt>
7474<dd>The standard deviation of the Gaussian, in pixels (default 1.0).</dd>
7475<dt>gain</dt>
7476<dd>The fraction of the difference between the original and the blur image that is added back into the original (default 1.0).</dd>
7477<dt>threshold</dt>
7478<dd>The threshold, as a fraction of <var>QuantumRange</var>, needed to apply the difference amount (default 0.05).</dd>
7479</dl>
7480
7481<div style="margin: auto;">
7482 <h3 class="magick-header"><a id="verbose"></a>-verbose</h3>
7483</div>
7484
7485<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>
7486
7487
7488<div style="margin: auto;">
7489 <h3 class="magick-header"><a id="version"></a>-version</h3>
7490</div>
7491
7492<p class="magick-description">print ImageMagick version string and exit.</p>
7493
7494
7495<div style="margin: auto;">
7496 <h3 class="magick-header"><a id="view"></a>-view <var>string</var></h3>
7497</div>
7498
7499<p class="magick-description">FlashPix viewing parameters.</p>
7500
7501
7502<div style="margin: auto;">
7503 <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>
7504</div>
7505
7506<p class="magick-description">soften the edges of the image in vignette style.</p>
7507
7508<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>
7509
7510<div style="margin: auto;">
7511 <h3 class="magick-header"><a id="virtual-pixel"></a>-virtual-pixel <var>method</var></h3>
7512</div>
7513
7514<p class="magick-description">Specify contents of <var>virtual pixels</var>.</p>
7515
7516<p>This option defines what color source should be used if and when a color
7517lookup completely 'misses' the source image. The color(s) that appear to
7518surround the source image. Generally this color is derived from the source
7519image, but could also be set to a specify background color. </p>
7520
7521<p>Choose from these methods:</p>
7522
7523<dl class="dl-horizontal">
7524<dt>background</dt><dd>the area surrounding the image is the background color</dd>
7525<dt>black</dt><dd>the area surrounding the image is black</dd>
7526<dt>checker-tile</dt><dd>alternate squares with image and background color</dd>
7527<dt>dither</dt><dd>non-random 32x32 dithered pattern</dd>
7528<dt>edge</dt><dd>extend the edge pixel toward infinity</dd>
7529<dt>gray</dt><dd>the area surrounding the image is gray</dd>
7530<dt>horizontal-tile</dt><dd>horizontally tile the image, background color above/below</dd>
7531<dt>horizontal-tile-edge</dt><dd>horizontally tile the image and replicate the side edge pixels</dd>
7532<dt>mirror</dt><dd>mirror tile the image</dd>
7533<dt>random</dt><dd>choose a random pixel from the image</dd>
7534<dt>tile</dt><dd>tile the image (default)</dd>
7535<dt>transparent</dt><dd>the area surrounding the image is transparent blackness</dd>
7536<dt>vertical-tile</dt><dd>vertically tile the image, sides are background color</dd>
7537<dt>vertical-tile-edge</dt><dd>vertically tile the image and replicate the side edge pixels</dd>
7538<dt>white</dt><dd>the area surrounding the image is white</dd>
7539</dl>
7540
7541<p>The default value is "edge".</p>
7542
7543<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>.
7544However it also effects operations that may access pixels just outside the
7545image 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>
7546
7547<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>
7548
7549
7550<div style="margin: auto;">
7551 <h3 class="magick-header"><a id="visual"></a>-visual <var>type</var></h3>
7552</div>
7553
7554<p class="magick-description">Animate images using this X visual type.", 'animate', 'display'</p>
7555
7556<p>Choose from these visual classes:</p>
7557
7558<pre>
7559StaticGray TrueColor
7560GrayScale DirectColor
7561StaticColor default
7562PseudoColor visual id
7563</pre>
7564
7565<p>The X server must support the visual you choose, otherwise an error occurs.
7566If a visual is not specified, the visual class that can display the most
7567simultaneous colors on the default screen is chosen.</p>
7568
7569
7570<div style="margin: auto;">
7571 <h3 class="magick-header"><a id="watermark"></a>-watermark <var>brightness</var>x<var>saturation</var></h3>
7572</div>
7573
7574<p class="magick-description">Watermark an image using the given percentages of brightness and saturation.</p>
7575
7576<p>Take a grayscale image (with alpha mask) and modify the destination image's
7577brightness according to watermark image's grayscale value and the
7578<var>brightness</var> percentage. The destinations color saturation
7579attribute is just direct modified by the <var>saturation</var>
7580percentage, which defaults to 100 percent (no color change). </p>
7581
7582
7583<div style="margin: auto;">
7584 <h3 class="magick-header"><a id="wave"></a>-wave <var>amplitude</var><br>-wave <var>amplitude</var>x<var>wavelength</var></h3>
7585</div>
7586
7587<p class="magick-description">Shear the columns of an image into a sine wave.</p>
7588
7589<p>Specify <var>amplitude</var> and <var>wavelength</var>
7590of the wave.</p>
7591
7592<div style="margin: auto;">
7593 <h3 class="magick-header"><a id="weight"></a>-weight <var>fontWeight</var></h3>
7594</div>
7595
7596<p class="magick-description">Set a font weight for text.</p>
7597
7598<p>This setting suggests a font weight that ImageMagick should try to apply to
7599the currently selected font family. Use a positive integer for
7600<var>fontWeight</var> or select from the following.</p>
7601
7602<dl class="dl-horizontal">
7603<dt>Thin </dt>
7604<dd>Same as <var>fontWeight</var> = 100.</dd>
7605<dt>ExtraLight </dt>
7606<dd>Same as <var>fontWeight</var> = 200.</dd>
7607<dt>Light </dt>
7608<dd>Same as <var>fontWeight</var> = 300.</dd>
7609<dt>Normal </dt>
7610<dd>Same as <var>fontWeight</var> = 400.</dd>
7611<dt>Medium </dt>
7612<dd>Same as <var>fontWeight</var> = 500.</dd>
7613<dt>DemiBold </dt>
7614<dd>Same as <var>fontWeight</var> = 600.</dd>
7615<dt>Bold </dt>
7616<dd>Same as <var>fontWeight</var> = 700.</dd>
7617<dt>ExtraBold </dt>
7618<dd>Same as <var>fontWeight</var> = 800.</dd>
7619<dt>Heavy </dt>
7620<dd>Same as <var>fontWeight</var> = 900.</dd>
7621</dl>
7622<br>
7623
7624<p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list weight</a>.</p>
7625
7626<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>
7627
7628<div style="margin: auto;">
7629 <h3 class="magick-header"><a id="white-point"></a>-white-point <var>x,y</var></h3>
7630</div>
7631
7632<p class="magick-description">chromaticity white point.</p>
7633
7634<div style="margin: auto;">
7635 <h3 class="magick-header"><a id="white-threshold"></a>-white-threshold <var>value</var>{<var>%</var>}</h3>
7636</div>
7637
7638<p class="magick-description">Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged.</p>
7639
7640<p> The threshold value can be given as a percentage or as an absolute integer
7641value within [0, <var>QuantumRange</var>] corresponding to the
7642desired <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>
7643
7644<div style="margin: auto;">
7645 <h3 class="magick-header"><a id="window"></a>-window <var>id</var></h3>
7646</div>
7647
7648<p class="magick-description">Make the image the background of a window.", 'animate', 'display'</p>
7649
7650<p><var>id</var> can be a window id or name. Specify <code>root</code>
7651to select X's root window as the target window.</p>
7652
7653<p>By default the image is tiled onto the background of the target window. If
7654<code>backdrop</code> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
7655image is surrounded by the background color. Refer to <code>X RESOURCES</code>
7656for details.</p>
7657
7658<p>The image will not display on the root window if the image has more unique
7659colors than the target window colormap allows. Use <a href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
7660
7661<div style="margin: auto;">
7662 <h3 class="magick-header"><a id="window-group"></a>-window-group</h3>
7663</div>
7664
7665<p class="magick-description">specify the window group.</p>
7666
7667<div style="margin: auto;">
7668 <h3 class="magick-header"><a id="write"></a>-write <var>filename</var></h3>
7669</div>
7670
7671<p class="magick-description">write an image sequence.</p>
7672
7673<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>
7674
7675<p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
7676</div>
7677</div>
7678
7679
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