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57<p class="text-center"><a href="command-line-options.html#adaptive-blur">‑adaptive‑blur</a> <span class="bull"> • </span> <a href="command-line-options.html#adaptive-resize">‑adaptive‑resize</a> <span class="bull"> • </span> <a href="command-line-options.html#adaptive-sharpen">‑adaptive‑sharpen</a> <span class="bull"> • </span> <a href="command-line-options.html#adjoin">‑adjoin</a> <span class="bull"> • </span> <a href="command-line-options.html#affine">‑affine</a> <span class="bull"> • </span> <a href="command-line-options.html#alpha">‑alpha</a> <span class="bull"> • </span> <a href="command-line-options.html#annotate">‑annotate</a> <span class="bull"> • </span> <a href="command-line-options.html#antialias">‑antialias</a> <span class="bull"> • </span> <a href="command-line-options.html#append">‑append</a> <span class="bull"> • </span> <a href="command-line-options.html#attenuate">‑attenuate</a> <span class="bull"> • </span> <a href="command-line-options.html#authenticate">‑authenticate</a> <span class="bull"> • </span> <a href="command-line-options.html#auto-gamma">‑auto‑gamma</a> <span class="bull"> • </span> <a href="command-line-options.html#auto-level">‑auto‑level</a> <span class="bull"> • </span> <a href="command-line-options.html#auto-orient">‑auto‑orient</a> <span class="bull"> • </span> <a href="command-line-options.html#backdrop">‑backdrop</a> <span class="bull"> • </span> <a href="command-line-options.html#background">‑background</a> <span class="bull"> • </span> <a href="command-line-options.html#bench">‑bench</a> <span class="bull"> • </span> <a href="command-line-options.html#bias">‑bias</a> <span class="bull"> • </span> <a href="command-line-options.html#black-point-compensation">‑black‑point‑compensation</a> <span class="bull"> • </span> <a href="command-line-options.html#black-threshold">‑black‑threshold</a> <span class="bull"> • </span> <a href="command-line-options.html#blend">‑blend</a> <span class="bull"> • </span> <a href="command-line-options.html#blue-primary">‑blue‑primary</a> <span class="bull"> • </span> <a href="command-line-options.html#blue-shift">‑blue‑shift</a> <span class="bull"> • </span> <a href="command-line-options.html#blur">‑blur</a> <span class="bull"> • </span> <a href="command-line-options.html#border">‑border</a> <span class="bull"> • </span> <a href="command-line-options.html#bordercolor">‑bordercolor</a> <span class="bull"> • </span> <a href="command-line-options.html#borderwidth">‑borderwidth</a> <span class="bull"> • </span> <a href="command-line-options.html#brightness-contrast">‑brightness‑contrast</a> <span class="bull"> • </span> <a href="command-line-options.html#cache">‑cache</a> <span class="bull"> • </span> <a href="command-line-options.html#canny">‑canny</a> <span class="bull"> • </span> <a href="command-line-options.html#caption">‑caption</a> <span class="bull"> • </span> <a href="command-line-options.html#cdl">‑cdl</a> <span class="bull"> • </span> <a href="command-line-options.html#channel">‑channel</a> <span class="bull"> • </span> <a href="command-line-options.html#charcoal">‑charcoal</a> <span class="bull"> • </span> <a href="command-line-options.html#chop">‑chop</a> <span class="bull"> • </span> <a href="command-line-options.html#clamp">‑clamp</a> <span class="bull"> • </span> <a href="command-line-options.html#clip">‑clip</a> <span class="bull"> • </span> <a href="command-line-options.html#clip-mask">‑clip‑mask</a> <span class="bull"> • </span> <a href="command-line-options.html#clip-path">‑clip‑path</a> <span class="bull"> • </span> <a href="command-line-options.html#clone">‑clone</a> <span class="bull"> • </span> <a href="command-line-options.html#clut">‑clut</a> <span class="bull"> • </span> <a href="command-line-options.html#coalesce">‑coalesce</a> <span class="bull"> • </span> <a href="command-line-options.html#colorize">‑colorize</a> <span class="bull"> • </span> <a href="command-line-options.html#colormap">‑colormap</a> <span class="bull"> • </span> <a href="command-line-options.html#color-matrix">‑color‑matrix</a> <span class="bull"> • </span> <a href="command-line-options.html#colors">‑colors</a> <span class="bull"> • </span> <a href="command-line-options.html#colorspace">‑colorspace</a> <span class="bull"> • </span> <a href="command-line-options.html#combine">‑combine</a> <span class="bull"> • </span> <a href="command-line-options.html#comment">‑comment</a> <span class="bull"> • </span> <a href="command-line-options.html#compare">‑compare</a> <span class="bull"> • </span> <a href="command-line-options.html#complex">‑complex</a> <span class="bull"> • </span> <a href="command-line-options.html#compose">‑compose</a> <span class="bull"> • </span> <a href="command-line-options.html#composite">‑composite</a> <span class="bull"> • </span> <a href="command-line-options.html#compress">‑compress</a> <span class="bull"> • </span> <a href="command-line-options.html#connected-components">‑connected‑components</a> <span class="bull"> • </span> <a href="command-line-options.html#contrast">‑contrast</a> <span class="bull"> • </span> <a href="command-line-options.html#contrast-stretch">‑contrast‑stretch</a> <span class="bull"> • </span> <a href="command-line-options.html#convolve">‑convolve</a> <span class="bull"> • </span> <a href="command-line-options.html#crop">‑crop</a> <span class="bull"> • </span> <a href="command-line-options.html#cycle">‑cycle</a> <span class="bull"> • </span> <a href="command-line-options.html#debug">‑debug</a> <span class="bull"> • </span> <a href="command-line-options.html#decipher">‑decipher</a> <span class="bull"> • </span> <a href="command-line-options.html#deconstruct">‑deconstruct</a> <span class="bull"> • </span> <a href="command-line-options.html#define">‑define</a> <span class="bull"> • </span> <a href="command-line-options.html#delay">‑delay</a> <span class="bull"> • </span> <a href="command-line-options.html#delete">‑delete</a> <span class="bull"> • </span> <a href="command-line-options.html#density">‑density</a> <span class="bull"> • </span> <a href="command-line-options.html#depth">‑depth</a> <span class="bull"> • </span> <a href="command-line-options.html#descend">‑descend</a> <span class="bull"> • </span> <a href="command-line-options.html#deskew">‑deskew</a> <span class="bull"> • </span> <a href="command-line-options.html#despeckle">‑despeckle</a> <span class="bull"> • </span> <a href="command-line-options.html#direction">‑direction</a> <span class="bull"> • </span> <a href="command-line-options.html#displace">‑displace</a> <span class="bull"> • </span> <a href="command-line-options.html#display">‑display</a> <span class="bull"> • </span> <a href="command-line-options.html#dispose">‑dispose</a> <span class="bull"> • </span> <a href="command-line-options.html#dissimilarity-threshold">‑dissimilarity‑threshold</a> <span class="bull"> • </span> <a href="command-line-options.html#dissolve">‑dissolve</a> <span class="bull"> • </span> <a href="command-line-options.html#distort">‑distort</a> <span class="bull"> • </span> <a href="command-line-options.html#distribute-cache">‑distribute‑cache</a> <span class="bull"> • </span> <a href="command-line-options.html#dither">‑dither</a> <span class="bull"> • </span> <a href="command-line-options.html#draw">‑draw</a> <span class="bull"> • </span> <a href="command-line-options.html#duplicate">‑duplicate</a> <span class="bull"> • </span> <a href="command-line-options.html#edge">‑edge</a> <span class="bull"> • </span> <a href="command-line-options.html#emboss">‑emboss</a> <span class="bull"> • </span> <a href="command-line-options.html#encipher">‑encipher</a> <span class="bull"> • </span> <a href="command-line-options.html#encoding">‑encoding</a> <span class="bull"> • </span> <a href="command-line-options.html#endian">‑endian</a> <span class="bull"> • </span> <a href="command-line-options.html#enhance">‑enhance</a> <span class="bull"> • </span> <a href="command-line-options.html#equalize">‑equalize</a> <span class="bull"> • </span> <a href="command-line-options.html#evaluate">‑evaluate</a> <span class="bull"> • </span> <a href="command-line-options.html#evaluate-sequence">‑evaluate‑sequence</a> <span class="bull"> • </span> <a href="command-line-options.html#extent">‑extent</a> <span class="bull"> • </span> <a href="command-line-options.html#extract">‑extract</a> <span class="bull"> • </span> <a href="command-line-options.html#family">‑family</a> <span class="bull"> • </span> <a href="command-line-options.html#features">‑features</a> <span class="bull"> • </span> <a href="command-line-options.html#fft">‑fft</a> <span class="bull"> • </span> <a href="command-line-options.html#fill">‑fill</a> <span class="bull"> • </span> <a href="command-line-options.html#filter">‑filter</a> <span class="bull"> • </span> <a href="command-line-options.html#flatten">‑flatten</a> <span class="bull"> • </span> <a href="command-line-options.html#flip">‑flip</a> <span class="bull"> • </span> <a href="command-line-options.html#floodfill">‑floodfill</a> <span class="bull"> • </span> <a href="command-line-options.html#flop">‑flop</a> <span class="bull"> • </span> <a href="command-line-options.html#font">‑font</a> <span class="bull"> • </span> <a href="command-line-options.html#foreground">‑foreground</a> <span class="bull"> • </span> <a href="command-line-options.html#format">‑format</a> <span class="bull"> • </span> <a href="command-line-options.html#format_identify_">‑format[identify]</a> <span class="bull"> • </span> <a href="command-line-options.html#frame">‑frame</a> <span class="bull"> • </span> <a href="command-line-options.html#frame_import_">‑frame[import]</a> <span class="bull"> • </span> <a href="command-line-options.html#function">‑function</a> <span class="bull"> • </span> <a href="command-line-options.html#fuzz">‑fuzz</a> <span class="bull"> • </span> <a href="command-line-options.html#fx">‑fx</a> <span class="bull"> • </span> <a href="command-line-options.html#gamma">‑gamma</a> <span class="bull"> • </span> <a href="command-line-options.html#gaussian-blur">‑gaussian‑blur</a> <span class="bull"> • </span> <a href="command-line-options.html#geometry">‑geometry</a> <span class="bull"> • </span> <a href="command-line-options.html#gravity">‑gravity</a> <span class="bull"> • </span> <a href="command-line-options.html#grayscale">‑grayscale</a> <span class="bull"> • </span> <a href="command-line-options.html#green-primary">‑green‑primary</a> <span class="bull"> • </span> <a href="command-line-options.html#hald-clut">‑hald‑clut</a> <span class="bull"> • </span> <a href="command-line-options.html#help">‑help</a> <span class="bull"> • </span> <a href="command-line-options.html#highlight-color">‑highlight‑color</a> <span class="bull"> • </span> <a href="command-line-options.html#hough-lines">‑hough‑lines</a> <span class="bull"> • </span> <a href="command-line-options.html#iconGeometry">‑iconGeometry</a> <span class="bull"> • </span> <a href="command-line-options.html#iconic">‑iconic</a> <span class="bull"> • </span> <a href="command-line-options.html#identify">‑identify</a> <span class="bull"> • </span> <a href="command-line-options.html#ift">‑ift</a> <span class="bull"> • </span> <a href="command-line-options.html#immutable">‑immutable</a> <span class="bull"> • </span> <a href="command-line-options.html#implode">‑implode</a> <span class="bull"> • </span> <a href="command-line-options.html#insert">‑insert</a> <span class="bull"> • </span> <a href="command-line-options.html#intensity">‑intensity</a> <span class="bull"> • </span> <a href="command-line-options.html#intent">‑intent</a> <span class="bull"> • </span> <a href="command-line-options.html#interlace">‑interlace</a> <span class="bull"> • </span> <a href="command-line-options.html#interpolate">‑interpolate</a> <span class="bull"> • </span> <a href="command-line-options.html#interline-spacing">‑interline‑spacing</a> <span class="bull"> • </span> <a href="command-line-options.html#interword-spacing">‑interword‑spacing</a> <span class="bull"> • </span> <a href="command-line-options.html#kerning">‑kerning</a> <span class="bull"> • </span> <a href="command-line-options.html#kuwahara">‑kuwahara</a> <span class="bull"> • </span> <a href="command-line-options.html#label">‑label</a> <span class="bull"> • </span> <a href="command-line-options.html#lat">‑lat</a> <span class="bull"> • </span> <a href="command-line-options.html#layers">‑layers</a> <span class="bull"> • </span> <a href="command-line-options.html#level">‑level</a> <span class="bull"> • </span> <a href="command-line-options.html#level-colors">‑level‑colors</a> <span class="bull"> • </span> <a href="command-line-options.html#limit">‑limit</a> <span class="bull"> • </span> <a href="command-line-options.html#linear-stretch">‑linear‑stretch</a> <span class="bull"> • </span> <a href="command-line-options.html#linewidth">‑linewidth</a> <span class="bull"> • </span> <a href="command-line-options.html#liquid-rescale">‑liquid‑rescale</a> <span class="bull"> • </span> <a href="command-line-options.html#list">‑list</a> <span class="bull"> • </span> <a href="command-line-options.html#log">‑log</a> <span class="bull"> • </span> <a href="command-line-options.html#loop">‑loop</a> <span class="bull"> • </span> <a href="command-line-options.html#lowlight-color">‑lowlight‑color</a> <span class="bull"> • </span> <a href="command-line-options.html#magnify">‑magnify</a> <span class="bull"> • </span> <a href="command-line-options.html#map">‑map</a> <span class="bull"> • </span> <a href="command-line-options.html#map_stream_">‑map[stream]</a> <span class="bull"> • </span> <a href="command-line-options.html#mask">‑mask</a> <span class="bull"> • </span> <a href="command-line-options.html#mattecolor">‑mattecolor</a> <span class="bull"> • </span> <a href="command-line-options.html#median">‑median</a> <span class="bull"> • </span> <a href="command-line-options.html#mean-shift">‑mean‑shift</a> <span class="bull"> • </span> <a href="command-line-options.html#metric">‑metric</a> <span class="bull"> • </span> <a href="command-line-options.html#mode">‑mode</a> <span class="bull"> • </span> <a href="command-line-options.html#modulate">‑modulate</a> <span class="bull"> • </span> <a href="command-line-options.html#moments">‑moments</a> <span class="bull"> • </span> <a href="command-line-options.html#monitor">‑monitor</a> <span class="bull"> • </span> <a href="command-line-options.html#monochrome">‑monochrome</a> <span class="bull"> • </span> <a href="command-line-options.html#morph">‑morph</a> <span class="bull"> • </span> <a href="command-line-options.html#morphology">‑morphology</a> <span class="bull"> • </span> <a href="command-line-options.html#mosaic">‑mosaic</a> <span class="bull"> • </span> <a href="command-line-options.html#motion-blur">‑motion‑blur</a> <span class="bull"> • </span> <a href="command-line-options.html#name">‑name</a> <span class="bull"> • </span> <a href="command-line-options.html#negate">‑negate</a> <span class="bull"> • </span> <a href="command-line-options.html#noise">‑noise</a> <span class="bull"> • </span> <a href="command-line-options.html#normalize">‑normalize</a> <span class="bull"> • </span> <a href="command-line-options.html#opaque">‑opaque</a> <span class="bull"> • </span> <a href="command-line-options.html#ordered-dither">‑ordered‑dither</a> <span class="bull"> • </span> <a href="command-line-options.html#orient">‑orient</a> <span class="bull"> • </span> <a href="command-line-options.html#page">‑page</a> <span class="bull"> • </span> <a href="command-line-options.html#paint">‑paint</a> <span class="bull"> • </span> <a href="command-line-options.html#path">‑path</a> <span class="bull"> • </span> <a href="command-line-options.html#pause_animate_">‑pause[animate]</a> <span class="bull"> • </span> <a href="command-line-options.html#pause_import_">‑pause[import]</a> <span class="bull"> • </span> <a href="command-line-options.html#perceptible">‑perceptible</a> <span class="bull"> • </span> <a href="command-line-options.html#ping">‑ping</a> <span class="bull"> • </span> <a href="command-line-options.html#pointsize">‑pointsize</a> <span class="bull"> • </span> <a href="command-line-options.html#polaroid">‑polaroid</a> <span class="bull"> • </span> <a href="command-line-options.html#poly">‑poly</a> <span class="bull"> • </span> <a href="command-line-options.html#posterize">‑posterize</a> <span class="bull"> • </span> <a href="command-line-options.html#precision">‑precision</a> <span class="bull"> • </span> <a href="command-line-options.html#preview">‑preview</a> <span class="bull"> • </span> <a href="command-line-options.html#print">‑print</a> <span class="bull"> • </span> <a href="command-line-options.html#process">‑process</a> <span class="bull"> • </span> <a href="command-line-options.html#profile">‑profile</a> <span class="bull"> • </span> <a href="command-line-options.html#quality">‑quality</a> <span class="bull"> • </span> <a href="command-line-options.html#quantize">‑quantize</a> <span class="bull"> • </span> <a href="command-line-options.html#quiet">‑quiet</a> <span class="bull"> • </span> <a href="command-line-options.html#radial-blur">‑radial‑blur</a> <span class="bull"> • </span> <a href="command-line-options.html#raise">‑raise</a> <span class="bull"> • </span> <a href="command-line-options.html#random-threshold">‑random‑threshold</a> <span class="bull"> • </span> <a href="command-line-options.html#red-primary">‑red‑primary</a> <span class="bull"> • </span> <a href="command-line-options.html#regard-warnings">‑regard‑warnings</a> <span class="bull"> • </span> <a href="command-line-options.html#region">‑region</a> <span class="bull"> • </span> <a href="command-line-options.html#remap">‑remap</a> <span class="bull"> • </span> <a href="command-line-options.html#remote">‑remote</a> <span class="bull"> • </span> <a href="command-line-options.html#render">‑render</a> <span class="bull"> • </span> <a href="command-line-options.html#repage">‑repage</a> <span class="bull"> • </span> <a href="command-line-options.html#resample">‑resample</a> <span class="bull"> • </span> <a href="command-line-options.html#resize">‑resize</a> <span class="bull"> • </span> <a href="command-line-options.html#respect-parentheses">‑respect‑parentheses</a> <span class="bull"> • </span> <a href="command-line-options.html#reverse">‑reverse</a> <span class="bull"> • </span> <a href="command-line-options.html#roll">‑roll</a> <span class="bull"> • </span> <a href="command-line-options.html#rotate">‑rotate</a> <span class="bull"> • </span> <a href="command-line-options.html#sample">‑sample</a> <span class="bull"> • </span> <a href="command-line-options.html#sampling-factor">‑sampling‑factor</a> <span class="bull"> • </span> <a href="command-line-options.html#scale">‑scale</a> <span class="bull"> • </span> <a href="command-line-options.html#scene">‑scene</a> <span class="bull"> • </span> <a href="command-line-options.html#screen">‑screen</a> <span class="bull"> • </span> <a href="command-line-options.html#seed">‑seed</a> <span class="bull"> • </span> <a href="command-line-options.html#segment">‑segment</a> <span class="bull"> • </span> <a href="command-line-options.html#selective-blur">‑selective‑blur</a> <span class="bull"> • </span> <a href="command-line-options.html#separate">‑separate</a> <span class="bull"> • </span> <a href="command-line-options.html#sepia-tone">‑sepia‑tone</a> <span class="bull"> • </span> <a href="command-line-options.html#set">‑set</a> <span class="bull"> • </span> <a href="command-line-options.html#shade">‑shade</a> <span class="bull"> • </span> <a href="command-line-options.html#shadow">‑shadow</a> <span class="bull"> • </span> <a href="command-line-options.html#shared-memory">‑shared‑memory</a> <span class="bull"> • </span> <a href="command-line-options.html#sharpen">‑sharpen</a> <span class="bull"> • </span> <a href="command-line-options.html#shave">‑shave</a> <span class="bull"> • </span> <a href="command-line-options.html#shear">‑shear</a> <span class="bull"> • </span> <a href="command-line-options.html#sigmoidal-contrast">‑sigmoidal‑contrast</a> <span class="bull"> • </span> <a href="command-line-options.html#silent">‑silent</a> <span class="bull"> • </span> <a href="command-line-options.html#similarity-threshold">‑similarity‑threshold</a> <span class="bull"> • </span> <a href="command-line-options.html#size">‑size</a> <span class="bull"> • </span> <a href="command-line-options.html#sketch">‑sketch</a> <span class="bull"> • </span> <a href="command-line-options.html#smush">‑smush</a> <span class="bull"> • </span> <a href="command-line-options.html#snaps">‑snaps</a> <span class="bull"> • </span> <a href="command-line-options.html#solarize">‑solarize</a> <span class="bull"> • </span> <a href="command-line-options.html#sparse-color">‑sparse‑color</a> <span class="bull"> • </span> <a href="command-line-options.html#splice">‑splice</a> <span class="bull"> • </span> <a href="command-line-options.html#spread">‑spread</a> <span class="bull"> • </span> <a href="command-line-options.html#statistic">‑statistic</a> <span class="bull"> • </span> <a href="command-line-options.html#stegano">‑stegano</a> <span class="bull"> • </span> <a href="command-line-options.html#stereo">‑stereo</a> <span class="bull"> • </span> <a href="command-line-options.html#stretch">‑stretch</a> <span class="bull"> • </span> <a href="command-line-options.html#strip">‑strip</a> <span class="bull"> • </span> <a href="command-line-options.html#stroke">‑stroke</a> <span class="bull"> • </span> <a href="command-line-options.html#strokewidth">‑strokewidth</a> <span class="bull"> • </span> <a href="command-line-options.html#style">‑style</a> <span class="bull"> • </span> <a href="command-line-options.html#subimage-search">‑subimage‑search</a> <span class="bull"> • </span> <a href="command-line-options.html#swap">‑swap</a> <span class="bull"> • </span> <a href="command-line-options.html#swirl">‑swirl</a> <span class="bull"> • </span> <a href="command-line-options.html#synchronize">‑synchronize</a> <span class="bull"> • </span> <a href="command-line-options.html#taint">‑taint</a> <span class="bull"> • </span> <a href="command-line-options.html#text-font">‑text‑font</a> <span class="bull"> • </span> <a href="command-line-options.html#texture">‑texture</a> <span class="bull"> • </span> <a href="command-line-options.html#threshold">‑threshold</a> <span class="bull"> • </span> <a href="command-line-options.html#thumbnail">‑thumbnail</a> <span class="bull"> • </span> <a href="command-line-options.html#tile">‑tile</a> <span class="bull"> • </span> <a href="command-line-options.html#tile-offset">‑tile‑offset</a> <span class="bull"> • </span> <a href="command-line-options.html#tint">‑tint</a> <span class="bull"> • </span> <a href="command-line-options.html#title">‑title</a> <span class="bull"> • </span> <a href="command-line-options.html#transform">‑transform</a> <span class="bull"> • </span> <a href="command-line-options.html#transparent">‑transparent</a> <span class="bull"> • </span> <a href="command-line-options.html#transparent-color">‑transparent‑color</a> <span class="bull"> • </span> <a href="command-line-options.html#transpose">‑transpose</a> <span class="bull"> • </span> <a href="command-line-options.html#transverse">‑transverse</a> <span class="bull"> • </span> <a href="command-line-options.html#treedepth">‑treedepth</a> <span class="bull"> • </span> <a href="command-line-options.html#trim">‑trim</a> <span class="bull"> • </span> <a href="command-line-options.html#type">‑type</a> <span class="bull"> • </span> <a href="command-line-options.html#undercolor">‑undercolor</a> <span class="bull"> • </span> <a href="command-line-options.html#unique-colors">‑unique‑colors</a> <span class="bull"> • </span> <a href="command-line-options.html#units">‑units</a> <span class="bull"> • </span> <a href="command-line-options.html#unsharp">‑unsharp</a> <span class="bull"> • </span> <a href="command-line-options.html#update">‑update</a> <span class="bull"> • </span> <a href="command-line-options.html#verbose">‑verbose</a> <span class="bull"> • </span> <a href="command-line-options.html#version">‑version</a> <span class="bull"> • </span> <a href="command-line-options.html#view">‑view</a> <span class="bull"> • </span> <a href="command-line-options.html#vignette">‑vignette</a> <span class="bull"> • </span> <a href="command-line-options.html#virtual-pixel">‑virtual‑pixel</a> <span class="bull"> • </span> <a href="command-line-options.html#visual">‑visual</a> <span class="bull"> • </span> <a href="command-line-options.html#watermark">‑watermark</a> <span class="bull"> • </span> <a href="command-line-options.html#wave">‑wave</a> <span class="bull"> • </span> <a href="command-line-options.html#weight">‑weight</a> <span class="bull"> • </span> <a href="command-line-options.html#white-point">‑white‑point</a> <span class="bull"> • </span> <a href="command-line-options.html#white-threshold">‑white‑threshold</a> <span class="bull"> • </span> <a href="command-line-options.html#window">‑window</a> <span class="bull"> • </span> <a href="command-line-options.html#window-group">‑window‑group</a> <span class="bull"> • </span> <a href="command-line-options.html#write">‑write</a> </p>
cristyad41c0c2012-10-31 00:49:28 +0000[diff] [blame]58
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame^]59<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>
60
61<div style="margin: auto;">
62 <h4><a id="adaptive-blur"></a>-adaptive-blur <var>radius</var>[x<var>sigma</var>]</h4>
cristyad41c0c2012-10-31 00:49:28 +0000[diff] [blame]63</div>
64
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame^]65<p class="magick-description">Adaptively blur pixels, with decreasing effect near edges.</p>
cristy8ee7f242013-06-20 16:08:44 +0000[diff] [blame]66
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame^]67<p>A Gaussian operator of the given radius and standard deviation (<var>sigma</var>) is used. If <var>sigma</var> is not given it
68defaults to 1.</p>
69
70<div style="margin: auto;">
71 <h4><a id="adaptive-resize"></a>-adaptive-resize <var>geometry</var></h4>
cristy149d58c2013-08-07 19:44:54 +0000[diff] [blame]72</div>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame^]73
74<p class="magick-description">Resize the image using data-dependent triangulation.</p>
75
76<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>
77option defaults to data-dependent triangulation. Use the <a href="command-line-options.html#filter">-filter</a> to choose a different resampling algorithm.
78Offsets, if present in the geometry string, are ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
79
80<div style="margin: auto;">
81 <h4><a id="adaptive-sharpen"></a>-adaptive-sharpen <var>radius</var>[x<var>sigma</var>]</h4>
cristy149d58c2013-08-07 19:44:54 +0000[diff] [blame]82</div>
cristyd2432012015-05-04 23:15:15 +0000[diff] [blame^]83
84<p class="magick-description">Adaptively sharpen pixels, with increasing effect near edges.</p>
85
86<p>A Gaussian operator of the given radius and standard deviation
87(<var>sigma</var>) is used. If <var>sigma</var> is not given it
88defaults to 1.</p>
89
90<div style="margin: auto;">
91 <h4><a id="adjoin"></a>-adjoin</h4>
92</div>
93
94<p class="magick-description">Join images into a single multi-image file.</p>
95
96<p>This option is enabled by default. An attempt is made to save all images of
97an image sequence into the given output file. However, some formats, such as
98JPEG and PNG, do not support more than one image per file, and in that case
99ImageMagick is forced to write each image as a separate file. As such, if
100more than one image needs to be written, the filename given is modified by
101adding a <a href="command-line-options.html#scene">-scene</a> number before the suffix, in order to
102make distinct names for each image. </p>
103
104<p>Use <a href="command-line-options.html#adjoin">+adjoin</a> to force each image to be written to
105separate files, whether or not the file format allows multiple images per file
106(for example, GIF, MIFF, and TIFF). </p>
107
108<p>Including a C-style integer format string in the output filename will
109automagically enable <a href="command-line-options.html#adjoin">+adjoin</a> and are used to specify
110where the <a href="command-line-options.html#scene">-scene</a> number is placed in the filenames. These
111strings, such as '<code>%d</code>' or '<code>%03d</code>', are familiar to those
112who have used the standard <code>printf()</code>' C-library function. As an
113example, the command</p>
114
115<pre>
116convert logo: rose: -morph 15 my%02dmorph.jpg
117</pre>
118
119<p>will create a sequence of 17 images (the two given plus 15 more created by
120<a href="command-line-options.html#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg,
121my02morph.jpg, ..., my16morph.jpg. </p>
122
123<p>In summary, ImageMagick tries to write all images to one file, but will
124save to multiple files, if any of the following conditions exist...</p>
125<ol>
126<li>the output image's file format does not allow multi-image files,</li>
127<li>the <a href="command-line-options.html#adjoin">+adjoin</a> option is given, or</li>
128<li>a printf() integer format string (eg: "%d") is present in the output
129 filename.</li>
130</ol>
131
132
133<div style="margin: auto;">
134 <h4><a id="affine"></a>-affine
135 <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>]</h4>
136</div>
137
138<p class="magick-description">Set the drawing transformation matrix for combined rotating and scaling.</p>
139
140<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>
141
142<p>The matrix entries are entered as comma-separated numeric values either in
143quotes or without spaces. </p>
144
145<p>Internally, the transformation matrix has 3x3 elements, but three of them
146are omitted from the input because they are constant. The new (transformed)
147coordinates (<var>x'</var>, <var>y'</var>) of a pixel at
148position (<var>x</var>, <var>y</var>) in the original
149image are calculated using the following matrix equation.</p>
150
151<div class="eqn">
152<img alt="affine transformation" src="../images/affine.png">
153</div>
154
155<p> The size of the resulting image is that of the smallest rectangle that
156contains the transformed source image. The parameters
157<var>t<sub>x</sub></var> and <var>t<sub>y</sub></var>
158subsequently shift the image pixels so that those that are moved out of the
159image area are cut off.</p>
160
161<p>The transformation matrix complies with the left-handed pixel coordinate
162system: positive <var>x</var> and <var>y</var> directions
163are rightward and downward, resp.; positive rotation is clockwise.</p>
164
165<p> If the translation coefficients <var>t<sub>x</sub></var> and
166<var>t<sub>y</sub></var> are omitted they default to 0,0. Therefore,
167four parameters suffice for rotation and scaling without translation.</p>
168
169<p>Scaling by the factors <var>s<sub>x</sub></var> and
170<var>s<sub>y</sub></var> in the <var>x</var> and <var>y</var> directions,
171respectively, is accomplished with the following.</p>
172
173<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
174information </p>
175
176
177<pre>
178-affine <var>s<sub>x</sub></var>,0,0,<var>s<sub>y</sub></var>
179</pre>
180
181<p>Translation by a displacement (<var>t<sub>x</sub></var>, <var>t<sub>y</sub></var>) is accomplished like so:</p>
182
183<pre>
184-affine 1,0,0,1,<var>t<sub>x</sub></var>,<var>t<sub>y</sub></var>
185</pre>
186
187<p>Rotate clockwise about the origin (the upper left-hand corner) by an angle
188<var>a</var> by letting <var>c</var> = cos(<var>a</var>), <var>s</var>
189= sin(<var>a</var>), and using the following.</p>
190
191<pre>
192-affine <var>c</var>,<var>s</var>,-<var>s</var>,<var>c</var>
193</pre>
194
195<p>The cumulative effect of a sequence of <a href="command-line-options.html#affine">-affine</a>
196transformations 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
197of the individual transformations.</p>
198
199<p>An attempt is made to detect near-singular transformation matrices. If the
200matrix determinant has a sufficiently small absolute value it is rejected.</p>
201
202<div style="margin: auto;">
203 <h4><a id="alpha"></a>-alpha <var>type</var></h4>
204</div>
205
206<p class="magick-description">Gives control of the alpha/matte channel of an image.</p>
207
208<p>Used to set a flag on an image indicating whether or not to use existing alpha
209channel 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>
210
211
212<div class="table-responsive">
213<table class="table table-condensed table-striped">
214 <tbody>
215 <tr>
216 <th>Type</th>
217 <th>Description</th>
218 </tr>
219
220 <tr>
221 <td><code>Activate</code> or <code>On</code></td>
222 <td>
223 Enable the image's transparency channel. Note normally <code>Set</code>
224 should be used instead of this, unless you specifically need to
225 preserve existing (but specifically turned <code>Off</code>) transparency
226 channel. </td></tr>
227
228 <tr>
229 <td><code>Associate</code></td>
230 <td>
231 associate the alpha channel with the image.</td></tr>
232
233 <tr>
234 <td><code>Deactivate</code> or <code>Off</code></td>
235 <td>
236 Disables the image's transparency channel. Does not delete or change the
237 existing data, just turns off the use of that data.</td></tr>
238
239 <tr>
240 <td><code>Disassociate</code></td>
241 <td>
242 disassociate the alpha channel from the image.</td></tr>
243
244 <tr>
245 <td><code>Set</code></td>
246 <td>
247 Activates the alpha/matte channel. If it was previously turned off
248 then it also resets the channel to opaque. If the image already had
249 the alpha channel turned on, it will have no effect.</td></tr>
250
251 <tr>
252 <td><code>Opaque</code></td>
253 <td>
254 Enables the alpha/matte channel and forces it to be fully opaque.
255 </td></tr>
256
257 <tr>
258 <td><code>Transparent</code></td>
259 <td>
260 Activates the alpha/matte channel and forces it to be fully
261 transparent. This effectively creates a fully transparent image the
262 same size as the original and with all its original RGB data still
263 intact, but fully transparent. </td></tr>
264
265 <tr>
266 <td><code>Extract</code></td>
267 <td>
268 Copies the alpha channel values into all the color channels and turns
269 '<code>Off</code>' the the image's transparency, so as to generate
270 a gray-scale mask of the image's shape. The alpha channel data is left
271 intact just deactivated. This is the inverse of '<code>Copy</code>'.
272 </td></tr>
273
274 <tr>
275 <td><code>Copy</code></td>
276 <td>
277 Turns '<code>On</code>' the alpha/matte channel, then copies the
278 gray-scale intensity of the image, into the alpha channel, converting
279 a gray-scale mask into a transparent shaped mask ready to be colored
280 appropriately. The color channels are not modified. </td></tr>
281
282 <tr>
283 <td><code>Shape</code></td>
284 <td>
285 As per '<code>Copy</code>' but also colors the resulting shape mask with
286 the current background color. That is the RGB color channels is
287 replaced, with appropriate alpha shape.
288 </td></tr>
289
290 <tr>
291 <td><code>Remove</code></td>
292 <td>
293 Composite the image over the background color.
294 </td></tr>
295
296 <tr>
297 <td><code>Background</code></td>
298 <td>
299 Set any fully-transparent pixel to the background color, while leaving
300 it fully-transparent. This can make some image file formats, such as
301 PNG, smaller as the RGB values of transparent pixels are more uniform,
302 and thus can compress better.
303 </td></tr>
304 </tbody>
305</table>
306</div>
307
308<p>Note that while the obsolete <code>+matte</code> operation was the
309same as "<code><a href="command-line-options.html#alpha">-alpha</a> Off</code>", the <code>
310&gt;-matte</code> operation was the same as "<code><a href="command-line-options.html#alpha">-alpha</a>
311Set</code>" and not "<code><a href="command-line-options.html#alpha">-alpha</a> On</code>". </p>
312
313
314<div style="margin: auto;">
315 <h4><a id="annotate"></a>
316 -annotate <var>degrees</var> <var>text</var><br>
317 -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></h4>
318</div>
319
320<p class="magick-description">Annotate an image with text</p>
321
322<p>This is a convenience for annotating an image with text. For more precise
323control over text annotations, use <a href="command-line-options.html#draw">-draw</a>.</p>
324
325
326<p>The values <var>Xdegrees</var> and <var>Ydegrees</var>
327control 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>
328
329<p>Using <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>
330or <a href="command-line-options.html#annotate">-annotate</a> <var>degrees</var>x<var>degrees</var> produces an unsheared rotation of the text. The
331direction of the rotation is positive, which means a clockwise rotation if <var>degrees</var> is positive. (This conforms to the usual mathematical
332convention once it is realized that the positive <var>y</var>–direction is
333conventionally considered to be <var>downward</var> for images.)</p>
334
335<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
336equation.</p> <div class="eqn"><img alt="annotate transformation" src="../images/annotate.png"></div>
337
338<p>If <var>t<sub>x</sub></var> and <var>t<sub>y</sub></var> are omitted, they default to 0. This makes the
339bottom-left of the text becomes the upper-left corner of the image, which is
340probably undesirable. Adding a <a href="command-line-options.html#gravity">-gravity</a> option in this
341case leads to nice results.</p>
342
343<p>Text is any UTF-8 encoded character sequence. If <var>text</var>
344is of the form '@mytext.txt', the text is read from the file
345<code>mytext.txt</code>. Text in a file is taken literally; no embedded
346formatting characters are recognized.</p>
347
348<div style="margin: auto;">
349 <h4><a id="antialias"></a>-antialias</h4>
350</div>
351
352<p class="magick-description">Enable/Disable of the rendering of anti-aliasing pixels when drawing fonts and lines.</p>
353
354<p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
355drawn. Use <a href="command-line-options.html#antialias">+antialias</a> to disable the addition of
356antialiasing edge pixels. This will then reduce the number of colors added to
357an image to just the colors being directly drawn. That is, no mixed colors
358are added when drawing such objects. </p>
359
360<div style="margin: auto;">
361 <h4><a id="append"></a>-append</h4>
362</div>
363
364<p class="magick-description">Join current images vertically or horizontally.</p>
365
366<p>This option creates a single longer image, by joining all the current
367images in sequence top-to-bottom. Use <a href="command-line-options.html#append">+append</a> to
368stack images left-to-right. </p>
369
370<p>If they are not of the same width, narrower images are padded with the
371current <a href="command-line-options.html#background">-background</a> color setting, and their
372position relative to each other can be controlled by the current <a href="command-line-options.html#gravity">-gravity</a> setting. </p>
373
374
375<div style="margin: auto;">
376 <h4><a id="attenuate"></a>-attenuate <var>value</var></h4>
377</div>
378
379<p class="magick-description">Lessen (or intensify) when adding noise to an image.</p>
380
381<p>If unset the value is equivalent to 1.0, or a maximum noise addition</p>
382
383<div style="margin: auto;">
384 <h4><a id="authenticate"></a>-authenticate <var>password</var></h4>
385</div>
386
387<p class="magick-description">Decrypt a PDF with a password.</p>
388
389<p>Use this option to supply a <var>password</var> for decrypting
390a PDF that has been encrypted using Microsoft Crypto API (MSC API). The
391encrypting using the MSC API is not supported.</p>
392
393<p>For a different encryption method, see <a href="command-line-options.html#encipher">-encipher</a>
394and <a href="command-line-options.html#decipher">-decipher</a>. </p>
395
396
397<div style="margin: auto;">
398 <h4><a id="auto-gamma"></a>-auto-gamma</h4>
399</div>
400
401<p class="magick-description">Automagically adjust gamma level of image.</p>
402
403<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
404image it will get a have a value of 50%. </p>
405
406<p>This means that any solid 'gray' image becomes 50% gray. </p>
407
408<p>This works well for real-life images with little or no extreme dark and
409light areas, but tend to fail for images with large amounts of bright sky or
410dark shadows. It also does not work well for diagrams or cartoon like images.
411</p>
412
413<p>It uses the <a href="command-line-options.html#channel">-channel</a> setting, (including the
414'<var>sync</var>' flag for channel synchronization), to determine which color
415values 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
416together by the same gamma value, preserving colors. </p>
417
418
419
420<div style="margin: auto;">
421 <h4><a id="auto-level"></a>-auto-level</h4>
422</div>
423
424<p class="magick-description">Automagically adjust color levels of image.</p>
425
426<p>This is a 'perfect' image normalization operator. It finds the exact
427minimum 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
428values. </p>
429
430<p>The operator is not typically used for real-life images, image scans, or
431JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
432for the <a href="command-line-options.html#level">-level</a> operation. On the other hand it is the
433right operator to use for color stretching gradient images being used to
434generate Color lookup tables, distortion maps, or other 'mathematically'
435defined images. </p>
436
437<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'
438problems 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>
439
440<p>It uses the <a href="command-line-options.html#channel">-channel</a> setting, (including the
441special '<var>sync</var>' flag for channel synchronization), to determine
442which 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
443'<var>sync</var>' ensures that the color channels will are modified
444together by the same gamma value, preserving colors, and ignoring
445transparency. </p>
446
447
448<div style="margin: auto;">
449 <h4><a id="auto-orient"></a>-auto-orient</h4>
450</div>
451
452<p class="magick-description">adjusts an image so that its orientation is suitable for viewing (i.e. top-left orientation).</p>
453
454<p>This operator reads and resets the EXIF image profile setting 'Orientation'
455and then performs the appropriate 90 degree rotation on the image to orient
456the image, for correct viewing. </p>
457
458<p>This EXIF profile setting is usually set using a gravity sensor in digital
459camera, however photos taken directly downward or upward may not have an
460appropriate value. Also images that have been orientation 'corrected' without
461reseting this setting, may be 'corrected' again resulting in a incorrect
462result. If the EXIF profile was previously stripped, the <a href="command-line-options.html#auto-orient">-auto-orient</a> operator will do nothing. </p>
463
464
465<div style="margin: auto;">
466 <h4><a id="average"></a>-average</h4>
467</div>
468
469<p class="magick-description">Average a set of images.</p>
470
471<p>An error results if the images are not identically sized.</p>
472
473
474<div style="margin: auto;">
475 <h4><a id="backdrop"></a>-backdrop</h4>
476</div>
477
478<p class="magick-description">Display the image centered on a backdrop.</p>
479
480<p>This backdrop covers the entire workstation screen and is useful for hiding
481other X window activity while viewing the image. The color of the backdrop is
482specified as the background color. The color is specified using the format
483described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
484
485<div style="margin: auto;">
486 <h4><a id="background"></a>-background <var>color</var></h4>
487</div>
488
489<p class="magick-description">Set the background color.</p>
490
491<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
492specified or found in the image) is white.</p>
493
494<div style="margin: auto;">
495 <h4><a id="bench"></a>-bench <var>iterations</var></h4>
496</div>
497
498<p class="magick-description">Measure performance.</p>
499
500<p>Repeat the entire command for the given number of <var>iterations</var> and report the user-time and elapsed time. For instance,
501consider the following command and its output. Modify the benchmark with the
502-duration to run the benchmark for a fixed number of seconds and -concurrent
503to run the benchmark in parallel (requires the OpenMP feature).</p>
504
505<pre>
506convert logo: -resize 1000% -bench 5 logo.png
507Performance[4]: 5i 0.875657ips 6.880u 0:05.710
508</pre>
509
510<p>In this example, 5 iterations were completed at 0.875657 iterations per
511second, using 4 threads and 6.88 seconds of the user's allotted time, for
512a total elapsed time of 5.71 seconds.</p>
513
514<div style="margin: auto;">
515 <h4><a id="bias"></a>-bias <var>value</var>{<var>%</var>}</h4>
516</div>
517
518<p class="magick-description">Add bias when convolving an image.</p>
519
520<p>This option shifts the output of <a href="command-line-options.html#convolve">‑convolve</a> so that
521positive and negative results are relative to the specified bias value. </p>
522
523<p>This is important for non-HDRI compilations of ImageMagick when dealing
524with convolutions that contain negative as well as positive values. This is
525especially the case with convolutions involving high pass filters or edge
526detection. Without an output bias, the negative values are clipped at
527zero.</p>
528
529<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
530negative results without clipping to the color value range
531(0..QuantumRange).</p>
532
533<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
534about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
535<a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
536entry. </p>
537
538<div style="margin: auto;">
539 <h4><a id="black-point-compensation"></a>-black-point-compensation</h4>
540</div>
541
542<p class="magick-description">Use black point compensation.</p>
543
544<div style="margin: auto;">
545 <h4><a id="black-threshold"></a>-black-threshold <var>value</var>{<var>%</var>}</h4>
546</div>
547
548<p class="magick-description">Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</p>
549
550<p> The threshold value can be given as a percentage or as an absolute integer
551value within [0, <var>QuantumRange</var>] corresponding to the
552desired <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>
553
554
555<div style="margin: auto;">
556 <h4><a id="blend"></a>-blend <var>geometry</var></h4>
557</div>
558
559<p class="magick-description">blend an image into another by the given absolute value or percent.</p>
560
561<p>Blend will average the images together ('plus') according to the
562percentages given and each pixels transparency. If only a single percentage
563value is given it sets the weight of the composite or 'source' image, while
564the background image is weighted by the exact opposite amount. That is a
565<code>-blend 30%</code> merges 30% of the 'source' image with 70% of the
566'destination' image. Thus it is equivalent to <code>-blend 30x70%</code>.</p>
567
568
569<div style="margin: auto;">
570 <h4><a id="blue-primary"></a>-blue-primary <var>x</var>,<var>y</var></h4>
571</div>
572
573<p class="magick-description">Set the blue chromaticity primary point.</p>
574
575<div style="margin: auto;">
576 <h4><a id="blue-shift"></a>-blue-shift <var>factor</var></h4>
577</div>
578
579<p class="magick-description">simulate a scene at nighttime in the moonlight. Start with a factor of 1.5</p>
580
581<div style="margin: auto;">
582
583<div style="margin: auto;">
584 <h4><a id="blur"></a>-blur <var>radius</var><br>-blur <var>radius</var>x<var>sigma</var></h4>
585</div>
586
587<p class="magick-description">Reduce image noise and reduce detail levels.</p>
588
589<p>Convolve the image with a Gaussian or normal distribution using the given
590<var>Sigma</var> value. The formula is:</p>
591
592<div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png">
593</div>
594
595<p>The <var>Sigma</var> value is the important argument, and
596determines the actual amount of blurring that will take place. </p>
597
598<p>The <var>Radius</var> is only used to determine the size of the
599array which will hold the calculated Gaussian distribution. It should be an
600integer. If not given, or set to zero, IM will calculate the largest possible
601radius that will provide meaningful results for the Gaussian distribution.
602</p>
603
604<p>The larger the <var>Radius</var> the slower the
605operation is. However too small a <var>Radius</var>, and sever
606aliasing effects may result. As a guideline, <var>Radius</var>
607should be at least twice the <var>Sigma</var> value, though three
608times will produce a more accurate result. </p>
609
610<p>This option differs from <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a> simply
611by taking advantage of the separability properties of the distribution. Here
612we apply a single-dimensional Gaussian matrix in the horizontal direction,
613then repeat the process in the vertical direction.</p>
614
615<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
616pixels which are outside the image proper are blurred into the final result.
617</p>
618
619
620<div style="margin: auto;">
621 <h4>-blur <var>Width</var>[x<var>Height</var>[+<var>Angle</var>]]</h4>
622</div>
623
624<p class="magick-description">Variably blur an image according to the overlay mapping.</p>
625
626<p>Each pixel in the overlaid region is replaced with an Elliptical Weighted
627Average (EWA) of the source image, scaled according to the grayscale
628mapping. </p>
629
630<p>The ellipse is weighted with sigma set to the given <var>Width</var> and <var>Height</var>. The <var>Height</var>
631defaults to the <var>Width</var> for a normal circular Gaussian
632weighting. The <var>Angle</var> will rotate the ellipse from
633horizontal clock-wise. </p>
634
635<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
636pixels which are outside the image proper are blurred into the final result.
637</p>
638
639
640<div style="margin: auto;">
641 <h4><a id="border"></a>-border <var>geometry</var></h4>
642</div>
643
644<p class="magick-description">Surround the image with a border of color. </p>
645
646<p>Set the width and height using the <var>size</var> portion of the
647<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
648ignored. </p>
649
650<p>As of IM 6.7.8-8, the <var>geometry</var> arguments behave as follows:</p>
651
652<table id="borderTable">
653 <col width="20%"> <col width="80%">
654 <thead>
655 <tr>
656 <th style="text-align:center"><var>size</var></th>
657 <th>General description</th>
658 </tr>
659 </thead>
660 <tbody>
661 <tr>
662 <td><var>value</var></td>
663 <td>value is added to both left/right and top/bottom</td>
664 </tr>
665 <tr>
666 <td><var>value-x</var>x</td>
667 <td>value-x is added only to left/right and top/bottom are unchanged</td>
668 </tr>
669 <tr>
670 <td>x<var>value-y</var></td>
671 <td>value-y is added only to top/bottom and left/right are unchanged</td>
672 </tr>
673 <tr>
674 <td><var>value-x</var>x<var>value-y</var></td>
675 <td>value-x is added to left/right and value-y added to top/bottom</td>
676 </tr>
677 <tr>
678 <td><var>value-x</var>x<code>0</code></td>
679 <td>value-x is added only to left/right and top/bottom are unchanged</td>
680 </tr>
681 <tr>
682 <td><code>0</code>x<var>value-y</var></td>
683 <td>value-y is added only to top/bottom and left/right are unchanged</td>
684 </tr>
685 <tr>
686 <td> </td>
687 <td> </td>
688 </tr>
689 <tr>
690 <td><var>value</var>%</td>
691 <td>value % of width is added to left/right and value % of height is added to top/bottom</td>
692 </tr>
693 <tr>
694 <td><var>value-x</var>x%</td>
695 <td>value-x % of width is added to left/right and to top/bottom</td>
696 </tr>
697 <tr>
698 <td>x<var>value-y</var>%</td>
699 <td>value-y % of height is added to top/bottom and to left/right</td>
700 </tr>
701 <tr>
702 <td><var>value-x</var>%x<var>value-y</var>%</td>
703 <td>value-x % of width is added to left/right and value-y % of height is added to top/bottom</td>
704 </tr>
705 <tr>
706 <td><var>value-x</var>%x<code>0</code>%</td>
707 <td>value-x % of width is added to left/right and top/bottom are unchanged</td>
708 </tr>
709 <tr>
710 <td><code>0</code>%x<var>value-y</var>%</td>
711 <td>value-y % of height is added to top/bottom and left/right are unchanged</td>
712 </tr>
713 </tbody>
714 </table>
715
716
717<p>Set the border color by preceding with the <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
718
719<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
720'<code>Over</code>' composition method. It generates an image of the appropriate
721size colors by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> before
722overlaying the original image in the center of this net image. This means that
723with the default compose method of '<code>Over</code>' any transparent parts may
724be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
725<p>See also the <a href="command-line-options.html#frame">-frame</a> option, which has more
726functionality.</p>
727
728<div style="margin: auto;">
729 <h4><a id="bordercolor"></a>-bordercolor <var>color</var></h4>
730</div>
731
732<p class="magick-description">Set the border color.</p>
733
734<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
735
736<p>The default border color is <code>#DFDFDF</code>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
737
738<div style="margin: auto;">
739 <h4><a id="borderwidth"></a>-borderwidth <var>geometry</var> </h4>
740</div>
741
742<p class="magick-description">Set the border width.</p>
743
744<div style="margin: auto;">
745 <h4><a id="brightness-contrast"></a>-brightness-contrast <var>brightness</var><br>-brightness-contrast <var>brightness</var>{x<var>contrast</var>}{<var>%</var>}}</h4>
746</div>
747
748<p class="magick-description">Adjust the brightness and/or contrast of the image.</p>
749
750<p>Brightness and Contrast values apply changes to the input image. They are
751not absolute settings. A brightness or contrast value of zero means no change.
752The range of values is -100 to +100 on each. Positive values increase the
753brightness or contrast and negative values decrease the brightness or contrast.
754To control only contrast, set the brightness=0. To control only brightness,
755set contrast=0 or just leave it off.</p>
756
757<p>You may also use <a href="command-line-options.html#fill">-channel</a> to control which channels to
758apply the brightness and/or contrast change. The default is to apply the same
759transformation to all channels.</p>
760
761<p>Brightness and Contrast arguments are converted to offset and slope of a
762linear transform and applied
763using <a href="command-line-options.html#fill">-function polynomial "slope,offset"</a>.</p>
764
765<p>The slope varies from 0 at contrast=-100 to almost vertical at
766contrast=+100. For brightness=0 and contrast=-100, the result are totally
767midgray. For brightness=0 and contrast=+100, the result will approach but
768not quite reach a threshold at midgray; that is the linear transformation
769is a very steep vertical line at mid gray.</p>
770
771<p>Negative slopes, i.e. negating the image, are not possible with this
772function. All achievable slopes are zero or positive.</p>
773
774<p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
775at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
776totally white. Similarly, when contrast=0 and brightness=-100, the result is
777totally black.</p>
778
779<p>As the range of values for the arguments are -100 to +100, adding the '%'
780symbol is no different than leaving it off.</p>
781
782<div style="margin: auto;">
783 <h4><a id="cache"></a>-cache <var>threshold</var></h4>
784</div>
785
786<p class="magick-description">(This option has been replaced by the <a href="command-line-options.html#limit">-limit</a> option).</p>
787
788<div style="margin: auto;">
789 <h4><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>}</h4>
790</div>
791
792<p class="magick-description">Canny edge detector uses a multi-stage algorithm to detect a wide range of edges in the image.</p>
793
794<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>
795
796<div style="margin: auto;">
797 <h4><a id="caption"></a>-caption <var>string</var></h4>
798</div>
799
800<p class="magick-description">Assign a caption to an image.</p>
801
802<p>This option sets the caption meta-data of an image read in after this
803option has been given. To modify a caption of images already in memory use
804"<code><a href="command-line-options.html#set">-set</a> caption</code>". </p>
805
806<p>The caption can contain special format characters listed in the <a href="escape.html">Format and
807Print Image Properties</a>. These attributes are expanded when the caption
808is finally assigned to the individual images. </p>
809
810<p>If the first character of <var>string</var> is <var>@</var>, the image caption is read from a file titled by the
811remaining characters in the string. Comments read in from a file are literal;
812no embedded formatting characters are recognized.</p>
813
814<p>Caption meta-data is not visible on the image itself. To do that use the
815<a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
816instead.</p>
817
818<p>For example,</p>
819
820<p class="crtsnip">
821 -caption "%m:%f %wx%h" bird.miff
822</p>
823
824<p>produces an image caption of <code>MIFF:bird.miff 512x480</code> (assuming
825that the image <code>bird.miff</code> has a width of 512 and a height of
826480.</p>
827
828
829<div style="margin: auto;">
830 <h4><a id="cdl"></a>-cdl <var>filename</var></h4>
831</div>
832
833<p class="magick-description">color correct with a color decision list.</p>
834
835<p>Here is an example color correction collection:</p>
836
837<pre>
838&lt;?xml version="1.0" encoding="UTF-8"?&gt;
839&lt;ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2"&gt;
840 &lt;ColorCorrection id="cc06668"&gt;
841 &lt;SOPNode&gt;
842 &lt;Slope&gt; 0.9 1.2 0.5 &lt;/Slope&gt;
843 &lt;Offset&gt; 0.4 -0.5 0.6 &lt;/Offset&gt;
844 &lt;Power&gt; 1.0 0.8 1.5 &lt;/Power&gt;
845 &lt;/SOPNode&gt;
846 &lt;SATNode&gt;
847 &lt;Saturation&gt; 0.85 &lt;/Saturation&gt;
848 &lt;/SATNode&gt;
849 &lt;/ColorCorrection&gt;
850&lt;/ColorCorrectionCollection&gt;
851</pre>
852
853<div style="margin: auto;">
854 <h4><a id="channel"></a>-channel <var>type</var></h4>
855</div>
856
857<p class="magick-description">Specify those image color channels to which subsequent operators are limited.</p>
858
859<p>Choose from: <code>Red</code>, <code>Green</code>, <code>Blue</code>,
860<code>Alpha</code>, <code>Gray</code>, <code>Cyan</code>, <code>Magenta</code>,
861<code>Yellow</code>, <code>Black</code>, <code>Opacity</code>,
862<code>Index</code>, <code>RGB</code>, <code>RGBA</code>, <code>CMYK</code>, or
863<code>CMYKA</code>.</p>
864
865<p>The channels above can also be specified as a comma-separated list or can be
866abbreviated as a concatenation of the letters '<code>R</code>', '<code>G</code>',
867'<code>B</code>', '<code>A</code>', '<code>O</code>', '<code>C</code>',
868'<code>M</code>', '<code>Y</code>', '<code>K</code>'.
869
870For example, to only select the <code>Red</code> and <code>Blue</code> channels
871you can either use </p>
872<p class="crtsnip">
873 -channel Red,Blue
874</p>
875<p>or you can use the short hand form</p>
876<p class="crtsnip">
877 -channel RB
878</p>
879
880<p>All the channels that are present in an image can be specified using the
881special channel type <code>All</code>. Not all operators are 'channel capable',
882but generally any operators that are generally 'grey-scale' image operators,
883will understand this setting. See individual operator documentation. </p>
884
885<br>
886
887<p>On top of the normal channel selection an extra flag can be specified,
888'<code>Sync</code>'. This is turned on by default and if set means that
889operators that understand this flag should perform: cross-channel
890synchronization of the channels. If not specified, then most grey-scale
891operators will apply their image processing operations to each individual
892channel (as specified by the rest of the <a href="command-line-options.html#channel">-channel</a>
893setting) completely independently from each other. </p>
894
895<p>For example for operators such as <a href="command-line-options.html#auto-level">-auto-level</a> and
896<a href="command-line-options.html#auto-gamma">-auto-gamma</a> the color channels are modified
897together in exactly the same way so that colors will remain in-sync. Without
898it being set, then each channel is modified separately and
899independently, which may produce color distortion. </p>
900
901<p>The <a href="command-line-options.html#morphology">-morphology</a> '<code>Convolve</code>' method
902and the <a href="command-line-options.html#compose">-compose</a> mathematical methods, also understands
903the '<code>Sync</code>' flag to modify the behaviour of pixel colors according
904to the alpha channel (if present). That is to say it will modify the image
905processing with the understanding that fully-transparent colors should not
906contribute to the final result. </p>
907
908<p>Basically, by default, operators work with color channels in synchronous, and
909treats transparency as special, unless the <a href="command-line-options.html#channel">-channel</a>
910setting is modified so as to remove the effect of the '<code>Sync</code>' flag.
911How each operator does this depends on that operators current implementation.
912Not all operators understands this flag at this time, but that is changing.
913</p>
914
915<p>To print a complete list of channel types, use <a href="command-line-options.html#list">-list
916channel</a>.</p>
917
918<br>
919
920<p>By default, ImageMagick sets <a href="command-line-options.html#channel">-channel</a> to the value
921'<code>RGBK,sync</code>', which specifies that operators act on all color
922channels except the transparency channel, and that all the color channels are
923to be modified in exactly the same way, with an understanding of transparency
924(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>
925
926<p>Options that are affected by the <a href="command-line-options.html#channel">-channel</a> setting
927include the following.
928
929<a href="command-line-options.html#auto-gamma">-auto-gamma</a>,
930<a href="command-line-options.html#auto-level">-auto-level</a>,
931<a href="command-line-options.html#black-threshold">-black-threshold</a>,
932<a href="command-line-options.html#blur">-blur</a>,
933<a href="command-line-options.html#clamp">-clamp</a>,
934<a href="command-line-options.html#clut">-clut</a>,
935<a href="command-line-options.html#combine">-combine</a>,
936<a href="command-line-options.html#composite">-composite</a> (Mathematical compose methods only),
937<a href="command-line-options.html#convolve">-convolve</a>,
938<a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
939<a href="command-line-options.html#evaluate">-evaluate</a>,
940<a href="command-line-options.html#function">-function</a>,
941<a href="command-line-options.html#fx">-fx</a>,
942<a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>,
943<a href="command-line-options.html#hald-clut">-hald-clut</a>,
944<a href="command-line-options.html#motion-blur">-motion-blur</a>,
945<a href="command-line-options.html#morphology">-morphology</a>,
946<a href="command-line-options.html#negate">-negate</a>,
947<a href="command-line-options.html#normalize">-normalize</a>,
948<a href="command-line-options.html#ordered-dither">-ordered-dither</a>,
949<a href="command-line-options.html#radial-blur">-radial-blur</a>,
950<a href="command-line-options.html#random-threshold">-random-threshold</a>,
951<a href="command-line-options.html#separate">-separate</a>,
952<a href="command-line-options.html#threshold">-threshold</a>, and
953<a href="command-line-options.html#white-threshold">-white-threshold</a>.
954</p>
955
956<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
957default). These operators have yet to be made to understand the newer 'Sync'
958flag. </p>
959
960<p>For example <a href="command-line-options.html#threshold">-threshold</a> will by default gray-scale
961the image before thresholding, if no <a href="command-line-options.html#channel">-channel</a> setting
962has been defined. This is not 'Sync flag controlled, yet. </p>
963
964<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
965color 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
966fully-transparent colors are treated as being fully-transparent, and thus any
967underlying 'hidden' color has no effect on the final results. Typically
968resulting in 'halo' effects. The newer <a href="command-line-options.html#morphology">-morphology</a>
969convolution equivalents however does have a understanding of the 'Sync' flag
970and will thus handle transparency correctly by default. </p>
971
972<p>As a alpha channel is optional within images, some operators will read the
973color channels of an image as a greyscale alpha mask, when the image has no
974alpha channel present, and the <a href="command-line-options.html#channel">-channel</a> setting tells
975the 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>
976
977
978
979<div style="margin: auto;">
980 <h4><a id="charcoal"></a>-charcoal <var>factor</var></h4>
981</div>
982
983<p class="magick-description">Simulate a charcoal drawing.</p>
984
985<div style="margin: auto;">
986 <h4><a id="chop"></a>-chop <var>geometry</var></h4>
987</div>
988
989<p class="magick-description">Remove pixels from the interior of an image.</p>
990
991<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>
992and <var>height</var> given in the of the <var>size</var>
993portion of the <var>geometry</var> argument give the number of
994columns and rows to remove. The <var>offset</var> portion of
995the <var>geometry</var> argument is influenced by
996a <a href="command-line-options.html#gravity">-gravity</a> setting, if present.</p>
997
998<p>The <a href="command-line-options.html#chop">-chop</a> option removes entire rows and columns,
999and moves the remaining corner blocks leftward and upward to close the gaps.</p>
1000
1001<p>While it can remove internal rows and columns of pixels, it is more
1002typically used with as <a href="command-line-options.html#gravity">-gravity</a> setting and zero
1003offsets 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 oppisite
1004sides of the image. </p>
1005
1006<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>
1007
1008<div style="margin: auto;">
1009 <h4><a id="clamp"></a>-clamp</h4>
1010</div>
1011
1012<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>
1013
1014<div style="margin: auto;">
1015 <h4><a id="clip"></a>-clip</h4>
1016</div>
1017
1018<p class="magick-description">Apply the clipping path if one is present.</p>
1019
1020<p>If a clipping path is present, it is applied to subsequent operations.</p>
1021
1022<p>For example, in the command</p>
1023
1024<pre>
1025convert cockatoo.tif -clip -negate negated.tif
1026</pre>
1027
1028<p>only the pixels within the clipping path are negated.</p>
1029
1030<p>The <a href="command-line-options.html#clip">-clip</a> feature requires SVG support. If the SVG
1031delegate library is not present, the option is ignored.</p>
1032
1033<p>Use <a href="command-line-options.html#clip">+clip</a> to disable clipping for subsequent operations.</p>
1034
1035<div style="margin: auto;">
1036 <h4><a id="clip-mask"></a>-clip-mask</h4>
1037</div>
1038
1039<p class="magick-description">Clip the image as defined by this mask.</p>
1040
1041<p>Use the alpha channel of the current image as a mask. Any areas that is
1042white is not modified by any of the 'image processing operators' that follow,
1043until the mask is removed. Pixels in the black areas of the clip mask are
1044modified per the requirements of the operator. </p>
1045
1046<p>In some ways this is similar to (though not the same) as defining
1047a rectangular <a href="command-line-options.html#region">-region</a>, or using the negative of the
1048mask (third) image in a three image <a href="command-line-options.html#composite">-composite</a>,
1049operation. </p>
1050
1051<p>Use <a href="command-line-options.html#clip-mask">+clip-mask</a> to disable clipping for subsequent operations.</p>
1052
1053<div style="margin: auto;">
1054 <h4><a id="clip-path"></a>-clip-path <var>id</var></h4>
1055</div>
1056
1057<p class="magick-description">Clip along a named path from the 8BIM profile.</p>
1058
1059<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>
1060
1061<p>Use <a href="command-line-options.html#clip-path">+clip-path</a> to disable clipping for subsequent operations.</p>
1062
1063<div style="margin: auto;">
1064 <h4><a id="clone"></a>-clone <var>index(s)</var></h4>
1065</div>
1066
1067<p class="magick-description">make a clone of an image (or images).</p>
1068
1069<p>Inside parenthesis (where the operator is normally used) it will make a
1070clone of the images from the last 'pushed' image sequence, and adds them to
1071the end of the current image sequence. Outside parenthesis
1072(not recommended) it clones the images from the current image sequence. </p>
1073
1074<p>Specify the image by its index in the sequence. The first image is index
10750. Negative indexes are relative to the end of the sequence; for
1076example, <code>−1</code>
1077represents the last image of the sequence. Specify a range of images with a
1078dash (e.g. <code>0−4</code>). Separate multiple indexes with commas but no
1079spaces (e.g. <code>0,2,5</code>). A value of '<code>0−−1</code> will
1080effectively clone all the images. </p>
1081
1082<p>The <a href="command-line-options.html#clone">+clone</a> will simply make a copy of the last image
1083in the image sequence, and is thus equivalent to using a argument of
1084'<code>−1</code>'. </p>
1085
1086<div style="margin: auto;">
1087 <h4><a id="clut"></a>-clut</h4>
1088</div>
1089
1090<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>
1091
1092<p>The second (LUT) image is ordinarily a gradient image containing the
1093histogram mapping of how each channel should be modified. Typically it is a
1094either a single row or column image of replacement color values. If larger
1095than a single row or column, values are taken from a diagonal line from
1096top-left to bottom-right corners.</p>
1097
1098<p>The lookup is further controlled by the <a href="command-line-options.html#interpolate">-interpolate</a> setting, which is especially handy for an
1099LUT which is not the full length needed by the ImageMagick installed Quality
1100(Q) level. Good settings for this are the '<code>bilinear</code>' and
1101'<code>bicubic</code>' interpolation settings, which give smooth color
1102gradients, and the '<code>integer</code>' setting for a direct, unsmoothed
1103lookup of color values. </p>
1104
1105<p>This operator is especially suited to replacing a grayscale image with a
1106specific color gradient from the CLUT image. </p>
1107
1108<p>Only the channel values defined by the <a href="command-line-options.html#channel">-channel</a>
1109setting 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
1110transparency (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
1111set, it is treated by the <a href="command-line-options.html#clut">-clut</a> operator in the same way
1112as the other channels, implying that alpha/matte values are replaced using the
1113alpha/matte values of the original image. </p>
1114
1115<p>If either the image being modified, or the lookup image, contains no
1116transparency (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
1117assumed that image represents a gray-scale gradient which is used for the
1118replacement alpha values. That is you can use a gray-scale CLUT image to
1119adjust a existing images alpha channel, or you can color a gray-scale image
1120using colors form CLUT containing the desired colors, including transparency.
1121</p>
1122
1123<p>See also <a href="command-line-options.html#hald-clut">-hald-clut</a> which replaces colors
1124according to the lookup of the full color RGB value from a 2D representation
1125of a 3D color cube. </p>
1126
1127
1128<div style="margin: auto;">
1129 <h4><a id="coalesce"></a>-coalesce</h4>
1130</div>
1131
1132<p class="magick-description">Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</p>
1133
1134<p>Overlay each image in an image sequence according to
1135its <a href="command-line-options.html#dispose">-dispose</a> meta-data, to reproduce the look of
1136an animation at each point in the animation sequence. All images should be
1137the same size, and are assigned appropriate GIF disposal settings for the
1138animation to continue working as expected as a GIF animation. Such frames
1139are more easily viewed and processed than the highly optimized GIF overlay
1140images. </p>
1141
1142<p>The animation can be re-optimized after processing using
1143the <a href="command-line-options.html#layers">-layers</a> method '<code>optimize</code>', although
1144there is no guarantee that the restored GIF animation optimization is
1145better than the original. </p>
1146
1147
1148<div style="margin: auto;">
1149 <h4><a id="colorize"></a>-colorize <var>value</var></h4>
1150</div>
1151
1152<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>
1153
1154<p>Specify the amount of colorization as a percentage. Separate colorization
1155values can be applied to the red, green, and blue channels of the image with
1156a comma-delimited list of colorization
1157values (e.g., <code>-colorize 0,0,50</code>).</p>
1158
1159<div style="margin: auto;">
1160 <h4><a id="colormap"></a>-colormap <var>type</var></h4>
1161</div>
1162
1163<p class="magick-description">Define the colormap type.</p>
1164
1165<p>The <var>type</var> can be <code>shared</code> or <code>private</code>.</p>
1166
1167<p>This option only applies when the default X server visual
1168is <code>PseudoColor</code> or <code>GrayScale</code>. Refer
1169to <a href="command-line-options.html#visual">-visual</a> for more details. By default,
1170a shared colormap is allocated. The image shares colors with
1171other X clients. Some image colors could be approximated,
1172therefore your image may look very different than intended.
1173If <code>private</code> is chosen, the image colors appear exactly
1174as they are defined. However, other clients may go <var>technicolor</var>
1175when the image colormap is installed.</p>
1176
1177<div style="margin: auto;">
1178 <h4><a id="colors"></a>-colors <var>value</var></h4>
1179</div>
1180
1181<p class="magick-description">Set the preferred number of colors in the image.</p>
1182
1183<p>The actual number of colors in the image may be less than your request,
1184but never more. Note that this a color reduction option. Images with fewer
1185unique colors than specified by <var>value</var> will have any
1186duplicate or unused colors removed. The ordering of an existing color
1187palette may be altered. When converting an image from color to grayscale,
1188it is more efficient to convert the image to the gray colorspace before
1189reducing the number of colors. Refer to
1190the <a href="quantize.html">
1191color reduction algorithm</a> for more details.</p>
1192
1193<div style="margin: auto;">
1194 <h4><a id="color-matrix"></a>-color-matrix <var>matrix</var></h4>
1195</div>
1196
1197<p class="magick-description">apply color correction to the image.</p>
1198
1199<p>This option permits saturation changes, hue rotation, luminance to alpha,
1200and various other effects. Although variable-sized transformation matrices
1201can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1202for CMYKA (or RGBA with offsets). The matrix is similar to those used by
1203Adobe Flash except offsets are in column 6 rather than 5 (in support of
1204CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1205
1206<p>As an example, to add contrast to an image with offsets, try this command:</p>
1207
1208<pre>
1209 convert kittens.jpg -color-matrix \
1210 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1211 0.0 1.5 0.0 0.0, 0.0, -0.157 \
1212 0.0 0.0 1.5 0.0, 0.0, -0.157 \
1213 0.0 0.0 0.0 1.0, 0.0, 0.0 \
1214 0.0 0.0 0.0 0.0, 1.0, 0.0 \
1215 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
1216</pre>
1217<div style="margin: auto;">
1218 <h4><a id="colorspace"></a>-colorspace <var>value</var></h4>
1219</div>
1220
1221<p class="magick-description">Set the image colorspace.</p>
1222
1223<p>Choices are:</p>
1224
1225<pre>
1226 CMY CMYK Gray HCL
1227 HCLp HSB HSI HSL
1228 HSV HWB Lab LCHab
1229 LCHuv LMS Log Luv
1230 OHTA Rec601YCbCr Rec709YCbCr RGB
1231 scRGB sRGB Transparent xyY
1232 XYZ YCbCr YCC YDbDr
1233 YIQ YPbPr YUV
1234</pre>
1235
1236<p>To print a complete list of colorspaces, use <a href="command-line-options.html#list">-list colorspace</a>.</p>
1237
1238<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>
1239
1240<table class="table table-condensed table-striped">
1241 <caption>Conversion of RGB to Other Color Spaces</caption>
1242 <tr><th valign="middle">CMY</th></tr>
1243 <tr><td valign="middle">C=<var>QuantumRange</var>−R</td></tr>
1244 <tr><td valign="middle">M=<var>QuantumRange</var>−G</td></tr>
1245 <tr><td valign="middle">Y=<var>QuantumRange</var>−B</td></tr>
1246 <tr><th valign="middle">CMYK — starts with CMY from above</th></tr>
1247 <tr><td valign="middle">K=min(C,Y,M)</td></tr>
1248 <tr><td valign="middle">C=<var>QuantumRange</var>*(C−K)/(<var>QuantumRange</var>−K)</td></tr>
1249 <tr><td valign="middle">M=<var>QuantumRange</var>*(M−K)/(<var>QuantumRange</var>−K)</td></tr>
1250 <tr><td valign="middle">Y=<var>QuantumRange</var>*(Y−K)/(<var>QuantumRange</var>−K)</td></tr>
1251
1252 <tr><th valign="middle">Gray</th></tr>
1253 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1254
1255 <tr><th valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1256 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1257 <tr><td valign="middle">S=distance from axis outward</td></tr>
1258 <tr><td valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <var>intensity-like</var></td></tr>
1259
1260 <tr><th valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr>
1261 <tr><td valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1262 <tr><td valign="middle">S=distance from axis outward</td></tr>
1263 <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>
1264
1265 <tr><th valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1266 <tr><td valign="middle">Hue (complicated equation)</td></tr>
1267 <tr><td valign="middle">Whiteness (complicated equation)</td></tr>
1268 <tr><td valign="middle">Blackness (complicated equation)</td></tr>
1269
1270 <tr><th valign="middle">LAB</th></tr>
1271 <tr><td valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1272 <tr><td valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1273 <tr><td valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1274
1275 <tr><th valign="middle">LOG</th></tr>
1276 <tr><td valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1277 <tr><td valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1278 <tr><td valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1279
1280 <tr><th valign="middle">OHTA — approximates principal components transformation</th></tr>
1281 <tr><td valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <var>intensity-like</var></td></tr>
1282 <tr><td valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1283 <tr><td valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1284
1285 <tr><th valign="middle">Rec601Luma</th></tr>
1286 <tr><td valign="middle">Gray = 0.298839*R+0.586811*G+0.114350*B</td></tr>
1287
1288 <tr><th valign="middle">Rec601YCbCr</th></tr>
1289 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1290 <tr><td valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1291 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1292
1293 <tr><th valign="middle">Rec709Luma</th></tr>
1294 <tr><td valign="middle">Gray=0.212656*R+0.715158*G+0.072186*B</td></tr>
1295
1296 <tr><th valign="middle">Rec709YCbCr</th></tr>
1297 <tr><td valign="middle">Y=0.212656*R+0.715158*G+0.072186*B; <var>intensity-like</var></td></tr>
1298 <tr><td valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1299 <tr><td valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)+(<var>QuantumRange</var>+1)/2</td></tr>
1300
1301 <tr><th valign="middle">sRGB</th></tr>
1302 <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>
1303 <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>
1304 <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>
1305
1306 <tr><th valign="middle">XYZ</th></tr>
1307 <tr><td valign="middle">X=0.4124564*R+0.3575761*G+0.1804375*B</td></tr>
1308 <tr><td valign="middle">Y=0.2126729*R+0.7151522*G+0.0721750*B</td></tr>
1309 <tr><td valign="middle">Z=0.0193339*R+0.1191920*G+0.9503041*B</td></tr>
1310
1311 <tr><th valign="middle">YCC</th></tr>
1312 <tr><td valign="middle">Y=(0.298839*R+0.586811*G+0.114350*B) (with complicated scaling); <var>intensity-like</var></td></tr>
1313 <tr><td valign="middle">C1=(−0.298839*R−0.586811*G+0.88600*B) (with complicated scaling)</td></tr>
1314 <tr><td valign="middle">C2=(0.70100*R−0.586811*G−0.114350*B) (with complicated scaling)</td></tr>
1315
1316 <tr><th valign="middle">YCbCr</th></tr>
1317 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1318 <tr><td valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1319 <tr><td valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1320
1321 <tr><th valign="middle">YIQ</th></tr>
1322 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1323 <tr><td valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1324 <tr><td valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1325
1326 <tr><th valign="middle">YPbPr</th></tr>
1327 <tr><td valign="middle">Y=0.2988390*R+0.5868110*G+0.1143500*B; <var>intensity-like</var></td></tr>
1328 <tr><td valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1329 <tr><td valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1330
1331 <tr><th valign="middle">YUV</th></tr>
1332 <tr><td valign="middle">Y=0.298839*R+0.586811*G+0.114350*B; <var>intensity-like</var></td></tr>
1333 <tr><td valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1334 <tr><td valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<var>QuantumRange</var>+1)/2</td></tr>
1335</table>
1336
1337<p>Note the scRGB colorspace requires HDRI support otherwise it behaves just like linear RGB.</p>
1338
1339<div style="margin: auto;">
1340 <h4><a id="combine"></a>-combine</h4>
1341</div>
1342
1343<p class="magick-description">Combine one or more images into a single image.</p>
1344
1345<p>The channels (previously set by <a href="command-line-options.html#channel">-channel</a>) of the
1346combined image are taken from the grayscale values of each image in the
1347sequence, in order. For the default -channel setting of <code>RGB</code>, this
1348means the first image is assigned to the <code>Red</code> channel, the second
1349to the <code>Green</code> channel, the third to the <code>Blue</code>.</p>
1350
1351<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.
1352Thus, in the following example, the final image should be a copy of the
1353original. </p>
1354
1355<pre>
1356convert original.png -channel RGB -separate sepimage.png
1357convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \
1358 -combine imagecopy.png
1359</pre>
1360
1361<div style="margin: auto;">
1362 <h4><a id="comment"></a>-comment <var>string</var></h4>
1363</div>
1364
1365<p class="magick-description">Embed a comment in an image.</p>
1366
1367<p>This option sets the comment meta-data of an image read in after this
1368option has been given. To modify a comment of images already in memory use
1369"<code><a href="command-line-options.html#set">-set</a> comment</code>". </p>
1370
1371<p>The comment can contain special format characters listed in the <a href="escape.html">Format and
1372Print Image Properties</a>. These attributes are expanded when the comment
1373is finally assigned to the individual images. </p>
1374
1375<p>If the first character of <var>string</var> is <var>@</var>, the image comment is read from a file titled by the
1376remaining characters in the string. Comments read in from a file are literal;
1377no embedded formatting characters are recognized.</p>
1378
1379<p>Comment meta-data are not visible on the image itself. To do that use the
1380<a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1381instead.</p>
1382
1383<p>For example,</p>
1384
1385<p class="crtsnip">
1386 -comment "%m:%f %wx%h" bird.miff
1387</p>
1388
1389<p>produces an image comment of <code>MIFF:bird.miff 512x480</code> (assuming
1390that the image <code>bird.miff</code> has a width of 512 and a height of
1391480.</p>
1392
1393<div style="margin: auto;">
1394 <h4><a id="compare"></a>-compare</h4>
1395</div>
1396
1397<p class="magick-description">mathematically and visually annotate the difference between an image and its reconstruction</p>
1398
1399<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>
1400
1401<pre>
1402convert image.png reference.png -metric RMSE -compare \ <br> difference.png
1403</pre>
1404
1405<p>To get the metric value use the string format "%[distortion]".</p>
1406
1407<pre>
1408convert image.png reference.png -metric RMSE -compare -format \
1409 "%[distortion]" info:
1410</pre>
1411
1412<div style="margin: auto;">
1413 <h4><a id="complex"></a>-complex <var>operator</var></h4>
1414</div>
1415
1416<p class="magick-description">perform complex mathematics on an image sequence</p>
1417
1418Choose from these operators:
1419
1420<pre>
1421 add
1422 conjugate
1423 divide
1424 magnuitude-phase
1425 multiply
1426 real-imaginary
1427 subtract
1428</pre>
1429
1430<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>
1431
1432<div style="margin: auto;">
1433 <h4><a id="compose"></a>-compose <var>operator</var></h4>
1434</div>
1435
1436<p class="magick-description">Set the type of image composition.</p>
1437
1438<p>See <a href="compose.html">Alpha Compositing</a> for
1439a detailed discussion of alpha compositing.</p>
1440
1441<p>This setting effects image processing operators that merge two (or more)
1442images together in some way. This includes the operators,
1443<a href="command-line-options.html#composite">-compare</a>,
1444<a href="command-line-options.html#composite">-composite</a>,
1445<a href="command-line-options.html#layers">-layers</a> composite,
1446<a href="command-line-options.html#flatten">-flatten</a>,
1447<a href="command-line-options.html#mosaic">-mosaic</a>,
1448<a href="command-line-options.html#layers">-layers</a> merge,
1449<a href="command-line-options.html#border">-border</a>,
1450<a href="command-line-options.html#frame">-frame</a>,
1451and <a href="command-line-options.html#extent">-extent</a>. </p>
1452
1453<p>It is also one of the primary options for the "<code>composite</code>"
1454command. </p>
1455
1456
1457<div style="margin: auto;">
1458 <h4><a id="composite"></a>-composite</h4>
1459</div>
1460
1461<p class="magick-description">Perform alpha composition on two images and an optional mask</p>
1462
1463<p>Take the first image 'destination' and overlay the second 'source' image
1464according to the current <a href="command-line-options.html#compose">-compose</a> setting. The location
1465of 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>
1466settings. </p>
1467
1468<p>If a third image is given this is treated as a gray-scale blending 'mask' image
1469relative to the first 'destination' image. This mask is blended with the
1470source image. However for the '<code>displace</code>' compose method, the
1471mask is used to provide a separate Y-displacement image instead. </p>
1472
1473<p>If a <a href="command-line-options.html#compose">-compose</a> method requires extra numerical
1474arguments or flags these can be provided by setting the <a href="command-line-options.html#set">-set</a> '<code>option:compose:args</code>'
1475appropriately for the compose method. </p>
1476
1477<p>Some <a href="command-line-options.html#compose">-compose</a> methods can modify the 'destination'
1478image 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>'
1479to '<code>false</code>'. </p>
1480
1481<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>
1482
1483
1484<div style="margin: auto;">
1485 <h4><a id="compress"></a>-compress <var>type</var></h4>
1486</div>
1487
1488<p class="magick-description">Use pixel compression specified by <var>type</var> when writing the image.</p>
1489
1490<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>
1491
1492<p>To print a complete list of compression types, use <a href="command-line-options.html#list">-list
1493compress</a>.</p>
1494
1495<p>Specify <a href="command-line-options.html#compress">+compress</a> to store the binary image in an
1496uncompressed format. The default is the compression type of the specified
1497image file.</p>
1498
1499<p>If <code>LZW</code> compression is specified but LZW compression has not been
1500enabled, the image data is written in an uncompressed LZW format that can be
1501read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1502
1503<p><code>Lossless</code> refers to lossless JPEG, which is only available if the
1504JPEG library has been patched to support it. Use of lossless JPEG is generally
1505not recommended.</p>
1506
1507<p>
1508When writing an ICO file, you may request that the images be encoded in
1509PNG format, by specifying <code>Zip</code> compression.</p>
1510
1511<p>
1512When writing a JNG file, specify <code>Zip</code> compression to request that
1513the alpha channel be encoded in PNG "IDAT" format, or <code>JPEG</code>
1514to request that it be encoded in JPG "JDAA" format.</p>
1515
1516<p>Use the <a href="command-line-options.html#quality">-quality</a> option to set the compression level
1517to be used by JPEG, PNG, MIFF, and MPEG encoders.
1518Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to set the
1519sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling
1520the chroma channels.</p>
1521
1522<div style="margin: auto;">
1523 <h4><a id="connected-components"></a>-connected-components <var>connectivity</var></h4>
1524</div>
1525
1526<p class="magick-description">connected-components uniquely labeled, choose from 4 or 8 way connectivity.</p>
1527
1528<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>
1529
1530<div style="margin: auto;">
1531 <h4><a id="contrast"></a>-contrast</h4>
1532</div>
1533
1534<p class="magick-description">Enhance or reduce the image contrast.</p>
1535
1536<p>This option enhances the intensity differences between the lighter and
1537darker elements of the image. Use <a href="command-line-options.html#contrast">-contrast</a> to enhance
1538the image or <a href="command-line-options.html#contrast">+contrast</a> to reduce the image
1539contrast.</p>
1540
1541<p>For a more pronounced effect you can repeat the option:</p>
1542
1543<pre>
1544convert rose: -contrast -contrast rose_c2.png
1545</pre>
1546
1547<div style="margin: auto;">
1548 <h4><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>}}</h4>
1549</div>
1550
1551<p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
1552
1553<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
1554<var>black-point %</var> pixels and white-out at most <var>white-point %</var> pixels.</p>
1555
1556<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
1557minus 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>
1558
1559<p>Note that <code>-contrast-stretch 0</code> will modify the image such that
1560the 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
1561clipping 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
1562prior to ImageMagick 6.4.7-0, <code>-contrast-stretch 2%x99%</code>).</p>
1563
1564<p>Internally operator works by creating a histogram bin, and then uses that
1565bin to modify the image. As such some colors may be merged together when they
1566originally fell into the same 'bin'. </p>
1567
1568<p>All the channels are normalized in concert by the came amount so as to
1569preserve color integrity, when the default <a href="command-line-options.html#channel">+channel</a>
1570setting is in use. Specifying any other <a href="command-line-options.html#channel">-channel</a>
1571setting will normalize the RGB channels independently.</p>
1572
1573<p>See also <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect'
1574normalization of mathematical images. </p>
1575
1576<p>This operator is under review for re-development. </p>
1577
1578
1579<div style="margin: auto;">
1580 <h4><a id="convolve"></a>-convolve <var>kernel</var></h4>
1581</div>
1582
1583<p class="magick-description">Convolve an image with a user-supplied convolution kernel.</p>
1584
1585<p>The <var>kernel</var> is a matrix specified as
1586a comma-separated list of integers (with no spaces), ordered left-to right,
1587starting with the top row. Presently, only odd-dimensioned kernels are
1588supported, and therefore the number of entries in the specified <var>kernel</var> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25,
15897<sup>2</sup>=49, etc. </p>
1590
1591<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
1592positive and negative results are relative to a user-specified bias value.
1593This is important for non-HDRI compilations of ImageMagick when dealing with
1594convolutions that contain negative as well as positive values. This is
1595especially the case with convolutions involving high pass filters or edge
1596detection. Without an output bias, the negative values is clipped at zero.
1597</p>
1598
1599<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
1600negative results without clipping to the color value range (0..QuantumRange).
1601See the discussion on HDRI implementations of ImageMagick on the page <a href="high-dynamic-range.html">High
1602Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
1603<a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1604entry. </p>
1605
1606
1607<div style="margin: auto;">
1608 <h4><a id="crop"></a>-crop <var>geometry</var>{<var>@</var>}{<var>!</var>}</h4>
1609</div>
1610
1611<p class="magick-description">Cut out one or more rectangular regions of the image.</p>
1612
1613<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1614
1615<p>The <var>width</var> and <var>height</var> of the <var>geometry</var> argument give the size of the image that remains
1616after cropping, and <var>x</var> and <var>y</var> in the
1617<var>offset</var> (if present) gives the location of the top left
1618corner of the cropped image with respect to the original image. To specify the
1619amount to be removed, use <a href="command-line-options.html#shave">-shave</a> instead.</p>
1620
1621<p>If the <var>x</var> and <var>y</var> offsets are
1622present, a single image is generated, consisting of the pixels from the
1623cropping region. The offsets specify the location of the upper left corner of
1624the cropping region measured downward and rightward with respect to the upper
1625left corner of the image. If the <a href="command-line-options.html#gravity">-gravity</a> option is
1626present with <code>NorthEast</code>, <code>East</code>, or <code>SouthEast</code>
1627gravity, it gives the distance leftward from the right edge of the image to
1628the 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>,
1629<code>South</code>, or <code>SouthEast</code> gravity, the distance is measured
1630upward between the bottom edges.</p>
1631
1632<p>If the <var>x</var> and <var>y</var> offsets are
1633omitted, a set of tiles of the specified geometry, covering the entire input
1634image, is generated. The rightmost tiles and the bottom tiles are smaller if
1635the specified geometry extends beyond the dimensions of the input image.</p>
1636
1637<p>You can add the <var>@</var> to the geometry argument to equally divide the image into the number of tiles generated.</p>
1638
1639<p>By adding a exclamation character flag to the geometry argument, the
1640cropped images virtual canvas page size and offset is set as if the
1641geometry argument was a viewport or window. This means the canvas page size
1642is set to exactly the same size you specified, the image offset set
1643relative top left corner of the region cropped. </p>
1644
1645<p>If the cropped image 'missed' the actual image on its virtual canvas, a
1646special single pixel transparent 'missed' image is returned, and a 'crop
1647missed' warning given. </p>
1648
1649<p>It might be necessary to <a href="command-line-options.html#repage">+repage</a> the image prior to
1650cropping the image to ensure the crop coordinate frame is relocated to the
1651upper-left corner of the visible image.
1652
1653Similarly you may want to use <a href="command-line-options.html#repage">+repage</a> after cropping to
1654remove the page offset that will be left behind. This is especially true when
1655you are going to write to an image format such as PNG that supports an image
1656offset.</p>
1657
1658<div style="margin: auto;">
1659 <h4><a id="cycle"></a>-cycle <var>amount</var></h4>
1660</div>
1661
1662<p class="magick-description">displace image colormap by amount.</p>
1663
1664<p><var>Amount</var> defines the number of positions each
1665colormap entry is shifted.</p>
1666
1667
1668<div style="margin: auto;">
1669 <h4><a id="debug"></a>-debug <var>events</var></h4>
1670</div>
1671
1672<p class="magick-description">enable debug printout.</p>
1673
1674<p>The <code>events</code> parameter specifies which events are to be logged. It
1675can be either <code>None</code>, <code>All</code>, <code>Trace</code>, or
1676a comma-separated list consisting of one or more of the following domains:
1677<code>Accelerate</code>, <code>Annotate</code>, <code>Blob</code>, <code>Cache</code>,
1678<code>Coder</code>, <code>Configure</code>, <code>Deprecate</code>,
1679<code>Exception</code>, <code>Locale</code>, <code>Render</code>,
1680<code>Resource</code>, <code>Security</code>, <code>TemporaryFile</code>,
1681<code>Transform</code>, <code>X11</code>, or <code>User</code>. </p>
1682
1683
1684<p>For example, to log cache and blob events, use.</p>
1685
1686<pre>
1687convert -debug "Cache,Blob" rose: rose.png
1688</pre>
1689
1690<p>The <code>User</code> domain is normally empty, but developers can log user
1691events in their private copy of ImageMagick.</p>
1692
1693<p>To print the complete list of debug methods, use <a href="command-line-options.html#list">-list
1694debug</a>.</p>
1695
1696<p>Use the <a href="command-line-options.html#log">-log</a> option to specify the format for debugging
1697output.</p>
1698
1699<p>Use <a href="command-line-options.html#debug">+debug</a> to turn off all logging.</p>
1700
1701<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>
1702environment variable are the same as for the <a href="command-line-options.html#debug">-debug</a>
1703option.</p>
1704
1705
1706<div style="margin: auto;">
1707 <h4><a id="decipher"></a>-decipher <var>filename</var></h4>
1708</div>
1709
1710<p class="magick-description">Decipher and restore pixels that were previously transformed by <a href="command-line-options.html#encipher">-encipher</a>.</p>
1711
1712<p>Get the passphrase from the file specified by <var>filename</var>.</p>
1713
1714<p>For more information, see the webpage, <a href="../cipher.html">ImageMagick: Encipher or
1715Decipher an Image</a>.</p>
1716
1717
1718<div style="margin: auto;">
1719 <h4><a id="deconstruct"></a>-deconstruct</h4>
1720</div>
1721
1722<p class="magick-description">find areas that has changed between images </p>
1723
1724<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
1725a smaller image of just the area that changed relative to the previous image.
1726</p>
1727
1728<p>The resulting sequence of images can be used to optimize an animation
1729sequence, though will not work correctly for GIF animations when parts of the
1730animation can go from opaque to transparent. </p>
1731
1732<p>This option is actually equivalent to the <a href="command-line-options.html#layers">-layers</a>
1733method '<code>compare-any</code>'. </p>
1734
1735
1736<div style="margin: auto;">
1737 <h4><a id="define"></a>-define <var>key</var>{<var>=value</var>}<var>...</var></h4>
1738</div>
1739
1740<p class="magick-description">add specific global settings generally used to control coders and image processing operations.</p>
1741
1742<p>This option creates one or more definitions for coders and decoders to use
1743while reading and writing image data. Definitions are generally used to
1744control image file format coder modules, and image processing operations,
1745beyond 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)
1746as "Artifacts". </p>
1747
1748<p>If <var>value</var> is missing for a definition, an empty-valued
1749definition of a flag is created with that name. This used to control on/off
1750options. Use <a href="command-line-options.html#define">+define key</a> to remove definitions
1751previously created. Use <a href="command-line-options.html#define">+define "*"</a> to remove all
1752existing definitions.</p>
1753
1754<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
1755Properties</a> in the defined value. </p>
1756
1757<p>The <var>option</var> and <var>key</var> are case-independent (they are
1758converted to lowercase for use within the decoders) while the <var>value</var>
1759is case-dependent.</p>
1760
1761<p>Such settings are global in scope, and affect all images and operations. </p>
1762
1763<p>The following definitions are just some of the artifacts that are
1764available:</p>
1765
1766<dl>
1767
1768<dt>bmp:format=<var>value</var></dt>
1769 <dd> valid values are <var>bmp2</var>, <var>bmp3</var>,
1770 and <var>bmp4</var>. This option can be useful when the
1771 method of prepending "BMP2:" to the output filename is inconvenient or
1772 is not available, such as when using the <a href="mogrify.html">mogrify</a> utility.</dd>
1773
1774<dt>complex:snr=<var>value</var></dt>
1775 <dd>Set the divide SNR constant<a href="command-line-options.html#complex">-complex</a></dd>
1776
1777<dt>compose:args=<var>arguments</var></dt>
1778 <dd>Sets certain compose argument values when using convert ... -compose ...
1779 -composite. See <a href="../compose.html">Image Composition</a></dd>
1780
1781<dt>convolve:scale=<var>{kernel_scale}[!^] [,{origin_addition}] [%]</var></dt>
1782 <dd>Defines the kernel scaling. The special flag ! automatically scales to
1783 full dynamic range. The ! flag can be used in combination with a factor or
1784 percent. The factor or percent is then applied after the automatic scaling.
1785 An example is 50%!. This produces a result 50% darker than full dynamic
1786 range scaling. The ^ flag assures the kernel is 'zero-summing', for
1787 example when some values are positive and some are negative as in edge
1788 detection kernels. The origin addition adds that value to the center
1789 pixel of the kernel. This produces and effect that is like adding the image
1790 that many times to the result of the filtered image. The typical value
1791 is 1 so that the original image is added to the result of the convolution.
1792 The default is 0.</dd>
1793
1794<dt>convolve:showkernel=<var>1</var></dt>
1795 <dd>Outputs (to 'standard error') all the information about a specified <a href="command-line-options.html#morphology">-morphology convolve</a> kernel.</dd>
1796
1797<dt>dcm:display-range=<var>reset</var></dt>
1798 <dd>Sets the display range to the minimum and maximum pixel values for the
1799 DCM image format.</dd>
1800
1801<dt>dds:cluster-fit=<var>true|false</var></dt>
1802 <dd>Enables the dds cluster-fit.</dd>
1803
1804<dt>dds:compression=<var>dxt1|dxt5|none</var></dt>
1805 <dd>Sets the dds compression.</dd>
1806
1807<dt>dds:mipmaps=<var>value</var></dt>
1808 <dd>Sets the dds number of mipmaps.</dd>
1809
1810<dt>dds:weight-by-alpha=<var>true|false</var></dt>
1811 <dd>Enables the dds alpha weighting.</dd>
1812
1813<dt>delegate:bimodal=<var>true</var></dt>
1814 <dd>Specifies direct conversion from Postscript to PDF.</dd>
1815
1816<dt>distort:scale=<var>value</var></dt>
1817 <dd>Sets the output scaling factor for use with <a href="command-line-options.html#distort">-distort</a></dd>
1818
1819<dt>distort:viewport=<var>WxH+X+Y</var></dt>
1820 <dd>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a></dd>
1821
1822<dt>dot:layout-engine=<var>value</var></dt>
1823 <dd>Specifies the layout engine for the DOT image format (e.g.
1824 <code>neato</code>).</dd>
1825
1826<dt>filter:option=<var>value</var></dt>
1827 <dd>Set a filter option for use with <a href="command-line-options.html#resize">-resize</a>.
1828 See <a href="command-line-options.html#filter">-filter</a> for details.</dd>
1829
1830<dt>fourier:normalize=<var>inverse</var></dt>
1831 <dd>Sets the location for the FFT/IFT normalization as use by
1832 <a href="command-line-options.html#fft">+-fft</a> and <a href="command-line-options.html#ift">+-ift</a>. The default is
1833 forward.</dd>
1834
1835<dt>icon:auto-resize</dt>
1836 <dd>Automatically stores multiple sizes when writing an ico image
1837 (requires a 256x256 input image).</dd>
1838
1839<dt>jp2:layer-number=<var>value</var></dt>
1840 <dd>Sets the maximum number of quality layers to decode. Same for JPT, JC2,
1841 and J2K</dd>
1842
1843<dt>jp2:number-resolutions=<var>value</var></dt>
1844 <dd>Sets the number of resolutions to encode.Same for JPT, JC2, and J2K</dd>
1845
1846<dt>jp2:progression-order=<var>value</var></dt>
1847 <dd>choose from LRCP, RLCP, RPCL, PCRL or CPRL. Same for JPT, JC2, and
1848 J2K</dd>
1849
1850<dt>jp2:quality=<var>value,value...</var></dt>
1851 <dd>Sets the quality layer PSNR, given in dB. The order is from left to
1852 right in ascending order. The default is a single lossless quality layer.
1853 Same for JPT, JC2, and J2K</dd>
1854
1855<dt>jp2:rate=<var>value</var></dt>
1856 <dd>Specify the compression factor to use while writing JPEG-2000 files. The
1857 compression factor is the reciprocal of the compression ratio. The valid
1858 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined,
1859 this value overrides the -quality setting. A quality setting of 75
1860 results in a rate value of 0.06641. Same for JPT, JC2, and J2K</dd>
1861
1862<dt>jp2:reduce-factor=<var>value</var></dt>
1863 <dd>Sets the number of highest resolution levels to be discarded.Same for
1864 JPT, JC2, and J2K</dd>
1865
1866<dt>jpeg:block-smoothing=<var>on|off</var></dt>
1867
1868<dt>jpeg:colors=<var>value</var></dt>
1869 <dd>Set the desired number of colors and let the JPEG encoder do the
1870 quantizing.</dd>
1871
1872<dt>jpeg:dct-method=<var>value</var></dt>
1873 <dd>Choose from <code>default</code>, <code>fastest</code>,
1874 <code>float</code>, <code>ifast</code>, and <code>islow</code>.</dd>
1875
1876<dt>jpeg:extent=<var>value</var></dt>
1877 <dd>Restrict the maximum JPEG file size, for example <code>-define
1878 jpeg:extent=400KB</code>. The JPEG encoder will search for the highest
1879 compression quality level that results in an output file that does not
1880 exceed the value. The <code>-quality</code> option is ignored if it
1881 is also present.</dd>
1882
1883<dt>jpeg:fancy-upsampling=<var>on|off</var></dt>
1884
1885<dt>jpeg:optimize-coding=<var>on|off</var></dt>
1886
1887<dt>jpeg:q-table=<var>table</var></dt>
1888
1889<dt>jpeg:sampling-factor=<var>sampling-factor-string</var></dt>
1890
1891<dt>jpeg:size=<var>geometry</var></dt>
1892 <dd>Set the size hint of a JPEG image, for
1893 example, <code>-define jpeg:size=128x128</code>.
1894 It is most useful for increasing performance and reducing the memory
1895 requirements when reducing the size of a large JPEG image.</dd>
1896
1897<dt>json:features</dt>
1898 <dd>includes features in verbose information</dd>
1899
1900<dt>json:limit</dt>
1901
1902<dt>json:locate</dt>
1903
1904<dt>json:moments</dt>
1905 <dd>includes image moments in verbose information</dd>
1906
1907<dt>mng:need-cacheoff</dt>
1908 <dd>turn playback caching off for streaming MNG.</dd>
1909
1910<dt>morphology:compose=<var>compose-method</var></dt>
1911 <dd>Specifies how to merge results generated by multiple<a href="command-line-options.html#morphology">-morphology</a> kernel. The default is none. One
1912 typical value is 'lighten' as used, for example, with the sobel edge
1913 kernels. </dd>
1914
1915<dt>morphology:showkernel=<var>1</var></dt>
1916 <dd>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</dd>
1917
1918<dt>pcl:fit-to-page=<var>true</var></dt>
1919
1920<dt>pdf:fit-page=<var>geometry</var></dt>
1921 <dd> geometry specifies the scaling dimensions for resizing when the PDF is
1922 being read. The geometry is either WxH{%} or page size. No offsets are
1923 allowed. (introduced in IM 6.8.8-8)</dd>
1924
1925<dt>pdf:fit-to-page=<var>true</var></dt>
1926
1927<dt>pdf:use-cropbox=<var>true</var></dt>
1928
1929<dt>pdf:use-trimbox=<var>true</var></dt>
1930
1931<dt>png:bit-depth=<var>value</var></dt>
1932<dt>png:color-type=<var>value</var></dt>
1933 <dd>desired bit-depth and color-type for PNG output. You can force the PNG
1934 encoder to use a different bit-depth and color-type than it would have
1935 normally selected, but only if this does not cause any loss of image
1936 quality. Any attempt to reduce image quality is treated as an error and no
1937 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
1938 can use these "defines" to cause it to be written as an 8-bit grayscale,
1939 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
1940 you cannot force it to be written as a grayscale or indexed PNG. If you
1941 wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
1942 <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
1943 reduce the image quality prior to using the PNG encoder. Note that in
1944 indexed PNG files, "bit-depth" refers to the number of bits per index,
1945 which can be 1, 2, 4, or 8. In such files, the color samples always have
1946 8-bit depth.</dd>
1947
1948<dt>png:compression-filter=<var>value</var></dt>
1949 <dd> valid values are 0 through 9. 0-4 are the corresponding PNG filters,
1950 5 means adaptive filtering except for images with a colormap, 6 means
1951 adaptive filtering for all images, 7 means MNG "loco" compression, 8 means
1952 Z_RLE strategy with adaptive filtering, and 9 means Z_RLE strategy with no
1953 filtering.</dd>
1954
1955<dt>png:compression-level=<var>value</var></dt>
1956 <dd> valid values are 0 through 9, with 0 providing the least but fastest
1957 compression and 9 usually providing the best and always the slowest.</dd>
1958
1959<dt>png:compression-strategy=<var>value</var></dt>
1960 <dd> valid values are 0 through 4, meaning default, filtered, huffman_only,
1961 rle, and fixed ZLIB compression strategy. If you are using an old zlib
1962 that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
1963 values 3 and 4, respectively, will use the zlib default strategy
1964 instead.</dd>
1965
1966<dt>png:format=<var>value</var></dt>
1967 <dd> valid values are <var>png8</var>, <var>png24</var>,
1968 <var>png32</var>, <var>png48</var>,
1969 <var>png64</var>, and <var>png00</var>.
1970 This property can be useful for specifying
1971 the specific PNG format to be used, when the usual method of prepending the
1972 format name to the output filename is inconvenient, such as when writing
1973 a PNG-encoded ICO file or when using <a href="mogrify.html">mogrify</a>.
1974 Value = <var>png8</var> reduces the number of colors to 256,
1975 only one of which may be fully transparent, if necessary. The other
1976 values do not force any reduction of quality; it is an error to request
1977 a format that cannot represent the image data without loss (except that
1978 it is allowed to reduce the bit-depth from 16 to 8 for all formats).
1979 Value = <var>png24</var> and <var>png48</var>
1980 allow transparency, only if a single color is fully transparent and that
1981 color does not also appear in an opaque pixel; such transparency is
1982 written in a PNG <code>tRNS</code> chunk.
1983 Value = <var>png00</var> causes the image to inherit its
1984 color-type and bit-depth from the input image, if the input was also
1985 a PNG.</dd>
1986
1987<dt>png:exclude-chunk=<var>value</var></dt>
1988
1989<dt>png:include-chunk=<var>value</var></dt>
1990 <dd>ancillary chunks to be excluded from or included in PNG output.
1991
1992 <p>The <var>value</var> can be the name of a PNG chunk-type such
1993 as <var>bKGD</var>, a comma-separated list of chunk-names
1994 (which can include the word <var>date</var>, the word
1995 <var>all</var>, or the word <var>none</var>).
1996 Although PNG chunk-names are case-dependent, you can use all lowercase
1997 names if you prefer.</p>
1998
1999 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
2000 of the PNG encoder and have no effect on the PNG decoder.</p>
2001
2002 <p>As a special case, if the <code>sRGB</code> chunk is excluded and
2003 the <code>gAMA</code> chunk is included, the <code>gAMA</code> chunk will
2004 only be written if gamma is not 1/2.2, since most decoders assume
2005 sRGB and gamma=1/2.2 when no colorspace information is included in
2006 the PNG file. Because the list is processed from left to right, you
2007 can achieve this with a single define:</p>
2008
2009<pre>
2010 -define png:include-chunk=none,gAMA
2011</pre>
2012
2013 <p>As a special case, if the <code>sRGB</code> chunk is not excluded and
2014 the PNG encoder recognizes that the image contains the sRGB ICC profile,
2015 the PNG encoder will write the <code>sRGB</code> chunk instead of the
2016 entire ICC profile. To force the PNG encoder to write the sRGB
2017 profile as an <code>iCCP</code> chunk in the output PNG instead of the
2018 <code>sRGB</code> chunk, exclude the <code>sRGB</code> chunk.</p>
2019
2020 <p>The critical PNG chunks <code>IHDR</code>, <code>PLTE</code>,
2021 <code>IDAT</code>, and <code>IEND</code> cannot be excluded. Any such
2022 entries appearing in the list will be ignored.</p>
2023
2024 <p>If the ancillary PNG <code>tRNS</code> chunk is excluded and the
2025 image has transparency, the PNG colortype is forced to be 4 or 6
2026 (GRAY_ALPHA or RGBA). If the image is not transparent, then the
2027 <code>tRNS</code> chunk isn't written anyhow, and there is no effect
2028 on the PNG colortype of the output image.</p>
2029
2030 <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2031 following for PNG output:</p>
2032
2033<pre>
2034 -define png:exclude-chunk=EXIF,iCCP,iTXt,sRGB,tEXt,zCCP,zTXt,date
2035</pre>
2036
2037 <p>The default behavior is to include all known PNG ancillary chunks
2038 plus ImageMagick's private <code>vpAg</code> ("virtual page") chunk,
2039 and to exclude all PNG chunks that are unknown to ImageMagick,
2040 regardless of their PNG "copy-safe" status as described in the
2041 PNG specification.</p>
2042
2043 <p>Any chunk names that are not known to ImageMagick are ignored
2044 if they appear in either the "include-chunk" or "exclude-chunk" list.
2045 The ancillary chunks currently known to ImageMagick are
2046 <code>bKGD</code>, <code>cHRM</code>, <code>gAMA</code>, <code>iCCP</code>,
2047 <code>oFFs</code>, <code>pHYs</code>, <code>sRGB</code>, <code>tEXt</code>,
2048 <code>tRNS</code>, <code>vpAg</code>, and <code>zTXt</code>.</p>
2049
2050 <p>You can also put <code>date</code> in the list to include or exclude
2051 the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2052 inserts in the output PNG.</p></dd>
2053
2054<dt>png:preserve-colormap[=<var>true</var>]</dt>
2055 <dd>Use the existing image-&gt;colormap. Normally the PNG encoder will
2056 try to optimize the palette, eliminating unused entries and putting
2057 the transparent colors first. If this flag is set, that behavior
2058 is suppressed.</dd>
2059
2060<dt>png:preserve-iCCP[=<var>true</var>]</dt>
2061 <dd>By default, the PNG decoder and encoder examine any ICC profile
2062 that is present, either from an <code>iCCP</code> chunk in the PNG
2063 input or supplied via an option, and if the profile is recognized
2064 to be the sRGB profile, converts it to the <code>sRGB</code> chunk.
2065 You can use <code>-define png:preserve-iCCP</code> to prevent
2066 this from happening; in such cases the <code>iCCP</code> chunk
2067 will be read or written and no <code>sRGB</code> chunk will be
2068 written. There are some ICC profiles that claim to be sRGB but
2069 have various errors that cause them to be rejected by libpng16; such
2070 profiles are recognized anyhow and converted to the <code>sRGB</code>
2071 chunk, but are rejected if the <code>-define png:preserve-iCCP</code>
2072 is present. Note that not all "sRGB" ICC profiles are recognized
2073 yet; we will add them to the list as we encounter them.</dd>
2074
2075<dt>png:swap-bytes[=<var>true</var>]</dt>
2076 <dd>The PNG specification requires that any multi-byte integers be stored in
2077 network byte order (MSB-LSB endian). This option allows you to
2078 fix any invalid PNG files that have 16-bit samples stored incorrectly
2079 in little-endian order (LSB-MSB). The "-define png:swap-bytes" option
2080 must appear before the input filename on the commandline. The swapping
2081 is done during the libpng decoding operation.</dd>
2082
2083<dt>profile:skip=<var>name1,name2,...</var></dt>
2084 <dd>Skip the named profile[s] when reading the image. Use skip="*" to
2085 skip all named profiles in the image. Many named profiles exist,
2086 including ICC, EXIF, APP1, IPTC, XMP, and others.</dd>
2087
2088<dt>ps:imagemask</dt>
2089 <dd>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create
2090 Postscript files that render bilevel images with the Postscript imagemask
2091 operator instead of the image operator.</dd>
2092
2093<dt>quantum:format=<var>type</var></dt>
2094 <dd>Set the type to <code>floating-point</code> to specify a floating-point
2095 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2096 to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2097 included, the result is a single precision floating point format.
2098 If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2099 double precision floating point format.</dd>
2100
2101<dt>quantum:polarity=<var>photometric-interpretation</var></dt>
2102 <dd>Set the photometric-interpretation of an image (typically for TIFF image
2103 file format) to either <code>min-is-black</code> (default) or
2104 <code>min-is-white</code>.</dd>
2105
2106<dt>sample:offset=<var>geometry</var></dt>
2107 <dd>Location of the sampling point within the sub-region being sampled,
2108 expressed as percentages (see <a href="command-line-options.html#sample">-sample</a>).</dd>
2109
2110<dt>showkernel=<var>1</var></dt>
2111 <dd>Outputs (to 'standard error') all the information about a generated <a href="command-line-options.html#morphology">-morphology</a> kernel.</dd>
2112
2113<dt>stream:buffer-size=<var>value</var></dt>
2114 <dd>Set the stream buffer size. Select 0 for unbuffered I/O.</dd>
2115
2116<dt>tiff:alpha=<var>associated|unassociated|unspecified</var></dt>
2117 <dd>Specify the alpha extra samples as associated, unassociated or unspecified </dd>
2118
2119<dt>tiff:endian=<var>msb|lsb</var></dt>
2120
2121<dt>tiff:exif-properties=<var>false</var></dt>
2122 <dd>Skips reading the EXIF properties.</dd>
2123
2124<dt>tiff:fill-order=<var>msb|lsb</var></dt>
2125
2126<dt>tiff:ignore-tags=<var>comma-separate-list-of-tag-IDs</var></dt>
2127 <dd>Allows one or more tag ID values to be ignored.</dd>
2128
2129<dt>tiff:rows-per-strip=<var>value</var></dt>
2130 <dd>Sets the number of rows per strip</dd>
2131
2132<dt>tiff:tile-geometry=<var>WxH</var></dt>
2133 <dd>Sets the tile size for pyramid tiffs. Requires the suffix
2134 PTIF: before the outputname</dd>
2135</dl>
2136
2137<p>For example, to create a postscript file that will render only the black
2138pixels of a bilevel image, use:</p>
2139
2140<pre>
2141convert bilevel.tif -define ps:imagemask eps3:stencil.ps
2142</pre>
2143
2144<p>Set attributes of the image registry by prefixing the value with
2145<code>registry:</code>. For example, to set a temporary path to put work files,
2146use:</p>
2147
2148<p class="crtsnip">
2149-define registry:temporary-path=/data/tmp
2150</p>
2151
2152<div style="margin: auto;">
2153 <h4><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>}</h4>
2154</div>
2155
2156<p class="magick-description">display the next image after pausing.</p>
2157
2158<p>This option is useful for regulating the animation of image sequences
2159<var>ticks/ticks-per-second</var> seconds must expire before the display of the
2160next image. The default is no delay between each showing of the image
2161sequence. The default ticks-per-second is 100.</p>
2162
2163<p>Use <code>&gt;</code> to change the image delay <var>only</var> if its current
2164value exceeds the given delay. <code>&lt;</code> changes the image delay
2165<var>only</var> if current value is less than the given delay. For example, if
2166you specify <code>30&gt;</code> and the image delay is 20, the image delay does
2167not change. However, if the image delay is 40 or 50, the delay it is changed
2168to 30. Enclose the given delay in quotation marks to prevent the
2169<code>&lt;</code> or <code>&gt;</code> from being interpreted by your shell as
2170a file redirection.</p>
2171
2172
2173<div style="margin: auto;">
2174 <h4><a id="delete"></a>-delete <var>indexes</var></h4>
2175</div>
2176
2177<p class="magick-description">delete the images specified by index, from the image sequence.</p>
2178
2179<p>Specify the image by its index in the sequence. The first image is index
21800. Negative indexes are relative to the end of the sequence, for example, -1
2181represents the last image of the sequence. Specify a range of images with
2182a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use
2183<code>+delete</code> to delete the last image in the current image sequence.</p>
2184
2185
2186<div style="margin: auto;">
2187 <h4><a id="density"></a>-density <var>width</var><br>-density <var>width</var>x<var>height</var></h4>
2188</div>
2189
2190<p class="magick-description">Set the horizontal and vertical resolution of an image for rendering to devices.</p>
2191
2192<p>This option specifies the image resolution to store while encoding a raster
2193image or the canvas resolution while rendering (reading) vector formats such
2194as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2195provides the unit of measure to apply when rendering to an output device or
2196raster 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
2197instead.</p>
2198
2199<p>The default resolution is 72 dots per inch, which is equivalent to one
2200point per pixel (Macintosh and Postscript standard). Computer screens are
2201normally 72 or 96 dots per inch, while printers typically support 150, 300,
2202600, or 1200 dots per inch. To determine the resolution of your display, use
2203a ruler to measure the width of your screen in inches, and divide by the
2204number of horizontal pixels (1024 on a 1024x768 display).</p>
2205
2206<p>If the file format supports it, this option may be used to update the
2207stored image resolution. Note that Photoshop stores and obtains image
2208resolution from a proprietary embedded profile. If this profile is not
2209stripped from the image, then Photoshop will continue to treat the image using
2210its former resolution, ignoring the image resolution specified in the standard
2211file header.</p>
2212
2213<p>The <a href="command-line-options.html#density">-density</a> option sets an <var>attribute</var> and
2214does not alter the underlying raster image. It may be used to adjust the
2215rendered size for desktop publishing purposes by adjusting the scale applied
2216to the pixels. To resize the image so that it is the same size at a different
2217resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2218
2219<div style="margin: auto;">
2220 <h4><a id="depth"></a>-depth <var>value</var></h4>
2221</div>
2222
2223<p class="magick-description">depth of the image.</p>
2224
2225<p>This the number of bits in a color sample within a pixel. Use this option
2226to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2227or CMYK, or to change the depth of any image after it has been read.</p>
2228
2229<div style="margin: auto;">
2230 <h4><a id="descend"></a>-descend</h4>
2231</div>
2232
2233<p class="magick-description">obtain image by descending window hierarchy.</p>
2234
2235<div style="margin: auto;">
2236 <h4><a id="deskew"></a>-deskew <var>threshold</var></h4>
2237</div>
2238
2239<p class="magick-description">straighten an image. A threshold of 40% works for most images.</p>
2240
2241<p>Use <a href="command-line-options.html#set">-set</a> <code>option:deskew:auto-crop
2242<var>width</var></code> to auto crop the image. The set argument is the pixel
2243width of the image background (e.g 40).</p>
2244
2245<div style="margin: auto;">
2246 <h4><a id="despeckle"></a>-despeckle</h4>
2247</div>
2248
2249<p class="magick-description">reduce the speckles within an image.</p>
2250
2251<div style="margin: auto;">
2252 <h4><a id="direction"></a>-direction <var>type</var></h4>
2253</div>
2254
2255<p class="magick-description">render text right-to-left or left-to-right.</p>
2256
2257<div style="margin: auto;">
2258 <h4><a id="displace"></a>-displace <var>horizontal-scale</var><br>-displace <var>horizontal-scale</var>x<var>vertical-scale</var></h4>
2259</div>
2260
2261<p class="magick-description">shift image pixels as defined by a displacement map.</p>
2262
2263<p>With this option, the 'overlay' image, and optionally the 'mask' image,
2264is used as a displacement map, which is used to displace the lookup of
2265what part of the 'background' image is seen at each point of the overlaid
2266area. Much like the displacement map is a 'lens' that redirects light shining
2267through it so as to present a distorted view the original 'background' image
2268behind it. </p>
2269
2270<p>Any perfect grey areas of the displacement map produce a zero
2271displacement of the image. Black areas produce the given maximum negative
2272displacement of the lookup point, while white produce a maximum positive
2273displacement of the lookup. </p>
2274
2275<p>Note that it is the lookup of the 'background' that is displaced, not a
2276displacement of the image itself. As such an area of the displacement map
2277containing 'white' will have the lookup point 'shifted' by a positive amount,
2278and thus generating a copy of the destination image to the right/downward from
2279the correct position. That is the image will look like it may have been
2280'shifted' in a negative left/upward direction. Understanding this is a very
2281important in understanding how displacement maps work. </p>
2282
2283<p>The given arguments define the maximum amount of displacement in pixels
2284that a particular map can produce. If the displacement scale is large enough
2285it is also possible to lookup parts of the 'background' image that lie well
2286outside the bounds of the displacement map itself. That is you could very
2287easily copy a section of the original image from outside the overlay area
2288into the overlay area. </p>
2289
2290<p>The '%' flag makes the displacement scale relative to the size of the
2291overlay image (100% = half width/height of image). Using '!' switches
2292percentage arguments to refer to the destination image size instead.
2293these flags were added as of IM v6.5.3-5.</p>
2294
2295<p>Normally a single grayscale displacement map is provided, which with the
2296given scaling values will determine a single direction (vector) in which
2297displacements can occur (positively or negatively). However, if you also
2298specify a third image which is normally used as a <var>mask</var>,
2299the <var>composite image</var> is used for horizontal X
2300displacement, while the <var>mask image</var> is used for vertical Y
2301displacement. This allows you to define completely different displacement
2302values for the X and Y directions, and allowing you to lookup any point within
2303the <var>scale</var> bounds. In other words each pixel can lookup
2304any other nearby pixel, producing complex 2 dimensional displacements, rather
2305than a simple 1 dimensional vector displacements. </p>
2306
2307<p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2308you can use the 'red' channel of the overlay image to specify the horizontal
2309or X displacement, and the 'green' channel for the vertical or Y displacement.
2310</p>
2311
2312<p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2313mask the transparency of the destination image. However areas outside the
2314overlaid areas will not be effected. </p>
2315
2316
2317<div style="margin: auto;">
2318 <h4><a id="display"></a>-display <var>host:display[.screen]</var></h4>
2319</div>
2320
2321<p class="magick-description">Specifies the X server to contact.</p>
2322
2323<p>This option is used with convert for obtaining image or font from this
2324X server. See <var>X(1)</var>.</p>
2325
2326<div style="margin: auto;">
2327 <h4><a id="dispose"></a>-dispose <var>method</var></h4>
2328</div>
2329
2330<p class="magick-description">define the GIF disposal image setting for images that are being created or read in. </p>
2331
2332<p>The layer disposal method defines the way each the displayed image is to be
2333modified after the current 'frame' of an animation has finished being
2334displayed (after its 'delay' period), but before the next frame on an
2335animation is to be overlaid onto the display. </p>
2336
2337<p>Here are the valid methods:</p>
2338
2339<pre>
2340 Undefined 0 No disposal specified (equivalent to '<code>none</code>').
2341 None 1 Do not dispose, just overlay next frame image.
2342 Background 2 Clear the frame area with the background color.
2343 Previous 3 Clear to the image prior to this frames overlay.
2344</pre>
2345
2346<p>You can also use the numbers given above, which is what the GIF format
2347uses internally to represent the above settings. </p>
2348
2349<p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2350
2351<p>Use <a href="command-line-options.html#dispose">+dispose</a>, turn off the setting and prevent
2352resetting the layer disposal methods of images being read in. </p>
2353
2354<p>Use <a href="command-line-options.html#set">-set</a> '<code>dispose</code>' method to set the image
2355disposal method for images already in memory.</p>
2356
2357<div style="margin: auto;">
2358 <h4><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <var>value</var></h4>
2359</div>
2360
2361<p class="magick-description">maximum RMSE for subimage match (default 0.2).</p>
2362
2363
2364<div style="margin: auto;">
2365 <h4><a id="dissolve"></a>-dissolve <var>src_percent</var>[x<var>dst_percent</var>]</h4>
2366</div>
2367
2368<p class="magick-description">dissolve an image into another by the given percent.</p>
2369
2370<p>The opacity of the composite image is multiplied by the given percent, then
2371it is composited 'over' the main image. If <var>src_percent</var>
2372is greater than 100, start dissolving the main image so it becomes
2373transparent at a value of '<code>200</code>'. If both percentages
2374are given, each image are dissolved to the percentages given. </p>
2375
2376<p>Note that dissolve percentages do not add, two opaque images dissolved
2377'50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2378images, you would need to use dissolve values of '50,100'. </p>
2379
2380<div style="margin: auto;">
2381 <h4><a id="distort"></a>-distort <var>method arguments</var></h4>
2382</div>
2383
2384<p class="magick-description">distort an image, using the given <var>method</var> and its required <var>arguments</var>.</p>
2385
2386<p>The <var>arguments</var> is a single string containing a list
2387of floating point numbers separated by commas or spaces. The number of
2388and meaning of the floating point values depends on the distortion <var>method</var> being used. </p>
2389
2390<p>Choose from these distortion types:</p>
2391
2392<table class="table table-condensed table-striped">
2393 <tr>
2394 <th style="width: 8%">Method</th>
2395 <th>Description</th>
2396 </tr>
2397
2398 <tr>
2399 <td><code>ScaleRotateTranslate</code>
2400 <br>or <code>SRT</code></td>
2401 <td>
2402 Distort image by first scaling and rotating about a given 'center',
2403 before translating that 'center' to the new location, in that order. It
2404 is an alternative method of specifying a '<code>Affine</code>' type of
2405 distortion, but without shearing effects. It also provides a good way
2406 of rotating and displacing a smaller image for tiling onto a larger
2407 background (IE 2-dimensional animations). <br>
2408
2409 The number of arguments determine the specific meaning of each
2410 argument for the scales, rotation, and translation operations. <br>
2411
2412 <table style="margin-left:auto; margin-right:auto;">
2413 <tr><td># </td><td>arguments meaning</td></tr>
2414 <tr><td>1:</td><td><var>Angle_of_Rotation</var></td></tr>
2415 <tr><td>2:</td><td><var>Scale Angle</var></td></tr>
2416 <tr><td>3:</td><td><var>X,Y Angle</var></td></tr>
2417 <tr><td>4:</td><td><var>X,Y Scale Angle</var></td></tr>
2418 <tr><td>5:</td>
2419 <td><var>X,Y ScaleX,ScaleY Angle</var></td></tr>
2420 <tr><td>6:</td>
2421 <td><var>X,Y Scale Angle NewX,NewY</var></td></tr>
2422 <tr><td>7:</td>
2423 <td><var>X,Y ScaleX,ScaleY Angle
2424 NewX,NewY</var></td></tr>
2425 </table>
2426
2427 This is actually an alternative way of specifying a 2 dimensional linear
2428 '<code>Affine</code>' or '<code>AffineProjection</code>' distortion. </td> </tr>
2429
2430 <tr>
2431 <td><code>Affine</code></td>
2432 <td>
2433 Distort the image linearly by moving a list of at least 3 or more sets
2434 of control points (as defined below). Ideally 3 sets or 12 floating
2435 point values are given allowing the image to be linearly scaled,
2436 rotated, sheared, and translated, according to those three points. See
2437 also the related '<code>AffineProjection</code>' and '<code>SRT</code>'
2438 distortions. <br>
2439
2440 More than 3 sets given control point pairs (12 numbers) is least
2441 squares fitted to best match a linear affine distortion. If only 2
2442 control point pairs (8 numbers) are given a two point image translation
2443 rotation and scaling is performed, without any possible shearing,
2444 flipping or changes in aspect ratio to the resulting image. If only one
2445 control point pair is provides the image is only translated, (which may
2446 be a floating point non-integer translation). <br>
2447
2448 This distortion does not include any form of perspective distortion.
2449 </td>
2450
2451 </tr>
2452
2453 <tr>
2454 <td><code>AffineProjection</code></td>
2455 <td>
2456 Linearly distort an image using the given Affine Matrix of 6
2457 pre-calculated coefficients forming a set of Affine Equations to map
2458 the source image to the destination image.
2459
2460 <div style="text-align: center"><var>
2461 s<sub>x</sub>, r<sub>x</sub>,
2462 r<sub>y</sub>, s<sub>y</sub>,
2463 t<sub>x</sub>, t<sub>y</sub>
2464 </var></div>
2465
2466 See <a href="command-line-options.html#affine">-affine</a> setting for more detail, and
2467 meanings of these coefficients. <br>
2468
2469 The distortions '<code>Affine</code>' and '<code>SRT</code>' provide
2470 alternative methods of defining this distortion, with ImageMagick doing
2471 the calculations needed to generate the required coefficients. You can
2472 see the internally generated coefficients, by using a <a href="command-line-options.html#verbose">-verbose</a> setting with those other variants. </td>
2473
2474 </tr>
2475
2476 <tr>
2477 <td><code>BilinearForward</code><br>
2478 <code>BilinearReverse</code></td>
2479 <td>
2480 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2481 16 values (see below). Not that lines may not appear straight after
2482 distortion, though the distance between coordinates will remain
2483 consistent. <br>
2484
2485 The '<code>BilinearForward</code>' is used to map rectangles to any
2486 quadrilateral, while the '<code>BilinearReverse</code>' form maps any
2487 quadrilateral to a rectangle, while preserving the straight line edges
2488 in each case. <br>
2489
2490 Note that '<code>BilinearForward</code>' can generate invalid pixels
2491 which will be colored using the <a href="command-line-options.html#mattecolor">-mattecolor</a>
2492 color setting. Also if the quadrilateral becomes 'flipped' the image
2493 may disappear. <br>
2494
2495 There are future plans to produce a true Bilinear distortion that will
2496 attempt to map any quadrilateral to any other quadrilateral, while
2497 preserving edges (and edge distance ratios).
2498
2499 </td>
2500 </tr>
2501
2502 <tr>
2503 <td><code>Perspective</code></td>
2504 <td>
2505 Perspective distort the images, using a list of 4 or more sets of
2506 control points (as defined below). More that 4 sets (16 numbers) of
2507 control points provide least squares fitting for more accurate
2508 distortions (for the purposes of image registration and panorama
2509 effects). Less than 4 sets will fall back to a '<code>Affine</code>'
2510 linear distortion. <br>
2511
2512 Perspective Distorted images ensures that straight lines remain
2513 straight, but the scale of the distorted image will vary. The horizon
2514 is anti-aliased, and the 'sky' color may be set using the
2515 <a href="command-line-options.html#mattecolor">-mattecolor</a> setting. </td>
2516 </tr>
2517
2518 <tr>
2519 <td><code>PerspectiveProjection</code> </td>
2520 <td>
2521 Do a '<code>Perspective</code>' distortion biased on a set of 8
2522 pre-calculated coefficients. You can get these coefficients by looking
2523 at the <a href="command-line-options.html#verbose">-verbose</a> output of a
2524 '<code>Perspective</code>' distortion, or by calculating them yourself.
2525 If the last two perspective scaling coefficients are zero, the
2526 remaining 6 represents a transposed 'Affine Matrix'. </td>
2527
2528 </tr>
2529
2530 <tr>
2531 <td><code>Arc</code></td>
2532 <td>
2533 Arc the image (variation of polar mapping) over the angle given around
2534 a circle. <br>
2535 <table width="90%" style="margin-left: auto; margin-right: auto;">
2536 <tr><td>Argument</td>
2537 <td>Meaning</td></tr>
2538 <tr><td><var>arc_angle</var></td>
2539 <td>The angle over which to arc the image side-to-side</td></tr>
2540 <tr><td><var>rotate_angle</var></td>
2541 <td>Angle to rotate resulting image from vertical center</td></tr>
2542 <tr><td><var>top_radius</var></td>
2543 <td>Set top edge of source image at this radius</td></tr>
2544 <tr><td><var>bottom_radius</var> </td>
2545 <td>Set bottom edge to this radius (radial scaling)</td></tr>
2546 </table>
2547
2548 The resulting image is always resized to best fit the resulting image,
2549 (as if using <a href="command-line-options.html#distort">+distort</a>) while attempting to
2550 preserve scale and aspect ratio of the original image as much as
2551 possible with the arguments given by the user. All four arguments will
2552 be needed to change the overall aspect ratio of an 'Arc'ed image. <br>
2553
2554 This a variation of a polar distortion designed to try to preserve the
2555 aspect ratio of the image rather than direct Cartesian to Polar
2556 conversion. </td>
2557 </tr>
2558
2559 <tr>
2560 <td><code>Polar</code></td>
2561 <td>
2562 Like '<code>Arc</code>' but do a complete Cartesian to Polar mapping of
2563 the image. that is the height of the input image is mapped to the
2564 radius limits, while the width is wrapped around between the
2565 angle limits. <br>
2566
2567 Arguments: <var>Rmax,Rmin CenterX,CenterY, start,end_angle</var> <br>
2568
2569 All arguments are optional. With <var>Rmin</var> defaulting to zero, the
2570 center to the center of the image, and the angles going from -180 (top)
2571 to +180 (top). If <var>Rmax</var> is given the special value of
2572 '<code>0</code>', the the distance from the center to the nearest edge
2573 is used for the radius of the output image, which will ensure the whole
2574 image is visible (though scaled smaller). However a special value of
2575 '<code>-1</code>' will use the distance from the center to the furthest
2576 corner, This may 'clip' the corners from the input rectangular image,
2577 but will generate the exact reverse of a '<code>DePolar</code>' with
2578 the same arguments. <br>
2579
2580 If the plus form of distort (<a href="command-line-options.html#distort">+distort</a>) is used
2581 output image center will default to <code>0,0</code> of the virtual
2582 canvas, and the image size adjusted to ensure the whole input image is
2583 made visible in the output image on the virtual canvas. </td>
2584
2585 </tr>
2586
2587 <tr>
2588 <td><code>DePolar</code></td>
2589 <td>
2590 Uses the same arguments and meanings as a '<code>Polar</code>' distortion
2591 but generates the reverse Polar to Cartesian distortion. <br>
2592
2593 The special <var>Rmax</var> setting of '<code>0</code>' may however clip
2594 the corners of the input image. However using the special
2595 <var>Rmax</var> setting of '<code>-1</code>' (maximum center to corner
2596 distance) will ensure the whole distorted image is preserved in the
2597 generated result, so that the same argument to '<code>Polar</code>' will
2598 reverse the distortion re-producing the original.
2599
2600 Note that as this distortion requires the area resampling of a circular
2601 arc, which can not be handled by the builtin EWA resampling function.
2602 As such the normal EWA filters are turned off. It is recommended some
2603 form of 'super-sampling' image processing technique be used to produce
2604 a high quality result. </td>
2605
2606 </tr>
2607
2608 <tr>
2609 <td><code>Barrel</code></td>
2610 <td>
2611 Given the four coefficients (A,B,C,D) as defined by <a href="http://wiki.panotools.org/Lens_correction_model">Helmut
2612 Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
2613 correct radial lens distortions. That is in photographs, make straight
2614 lines straight again. <br>
2615
2616 Arguments: <var>A B C</var> [ <var>D</var> [
2617 <var>X</var> , <var>Y</var> ] ] <br>
2618 or <var>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2619 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></var>
2620 [ <var>X</var> , <var>Y</var> ] <br>
2621 So that it forms the function <br>
2622 Rsrc = r * ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2623 <var>C</var>*r + <var>D</var> )<br>
2624
2625 Where <var>X</var>,<var>Y</var> is the optional center of the distortion
2626 (defaulting to the center of the image). <br>
2627 The second form is typically used to distort images, rather than
2628 correct lens distortions. <br>
2629 </td>
2630
2631 </tr>
2632
2633 <tr>
2634 <td><code>BarrelInverse</code></td>
2635 <td>
2636 This is very similar to '<code>Barrel</code>' with the same set of
2637 arguments, and argument handling. However it uses the inverse
2638 of the radial polynomial,
2639 so that it forms the function <br>
2640 Rsrc = r / ( <var>A</var>*r<sup>3</sup> + <var>B</var>*r<sup>2</sup> +
2641 <var>C</var>*r + <var>D</var> )<br>
2642 Note that this is not the reverse of the '<code>Barrel</code>'
2643 distortion, just a different barrel-like radial distortion method.
2644
2645 </td>
2646 </tr>
2647
2648 <tr>
2649 <td><code>Shepards</code></td>
2650 <td>
2651 Distort the given list control points (any number) using an Inverse
2652 Squared Distance Interpolation Method (<a href="http://en.wikipedia.org/wiki/Shepard%27s_method">Shepards
2653 Method</a>). The control points in effect do 'localized' displacement
2654 of the image around the given control point (preserving the look and
2655 the rotation of the area near the control points. For best results
2656 extra control points should be added to 'lock' the positions of the
2657 corners, edges and other unchanging parts of the image, to prevent
2658 their movement. <br>
2659
2660 The distortion has been likened to 'taffy pulling' using nails, or
2661 pins' stuck in a block of 'jelly' which is then moved to the new
2662 position, distorting the surface of the jelly. <br>
2663
2664 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
2665 the <a href="command-line-options.html#sparse-color">-sparse-color</a> method of the same name.
2666
2667 </td>
2668 </tr>
2669
2670</table>
2671
2672<p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
2673distort</a>.</p>
2674
2675<p>Many of the above distortion methods such as '<code>Affine</code>',
2676'<code>Perspective</code>', and '<code>Shepards</code>' use a list control points
2677defining how these points in the given image should be distorted in the
2678destination image. Each set of four floating point values represent a source
2679image coordinate, followed immediately by the destination image coordinate.
2680This produces a list of values such as...</p>
2681<div style="text-align: center"><var>
2682 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
2683 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
2684 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
2685 ...
2686 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
2687</var></div>
2688<p>where <var>U,V</var> on the source image is mapped to <var>X,Y</var> on the
2689destination image. </p>
2690
2691<p>For example, to warp an image using '<code>perspective</code>' distortion,
2692needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
2693perspective distortion of the built-in "rose:" image. Note how spaces were
2694used to group the 4 sets of coordinate pairs, to make it easier to read and
2695understand.</p>
2696
2697<pre>
2698convert rose: -virtual-pixel black \
2699 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \
2700 rose_3d_rotated.gif"
2701</pre>
2702
2703<p>If more that the required number of coordinate pairs are given for
2704a distortion, the distortion method is 'least squares' fitted to produce the
2705best result for all the coordinate pairs given. If less than the ideal number
2706of points are given, the distort will generally fall back to a simpler form of
2707distortion that can handles the smaller number of coordinates (usually a linear
2708'<code>Affine</code>' distortion). </p>
2709
2710<p>By using more coordinates you can make use of image registration tool to
2711find matching coordinate pairs in overlapping images, so as to improve the
2712'fit' of the distortion. Of course a bad coordinate pair can also make the
2713'fit' worse. Caution is always advised. </p>
2714
2715<p>Colors are acquired from the source image according to a cylindrical
2716resampling <a href="command-line-options.html#filter">-filter</a>, using a special technique known as
2717EWA resampling. This produces very high quality results, especially when
2718images become smaller (minified) in the output, which is very common when
2719using '<code>perspective</code>' distortion. For example here we view
2720a infinitely tiled 'plane' all the way to the horizon. </p>
2721
2722<pre>
2723convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \
2724 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \
2725 checks_tiled.jpg
2726</pre>
2727
2728<p>Note that a infinitely tiled perspective images involving the horizon can
2729be very slow, because of the number of pixels that are compressed to generate
2730each individual pixel close to the 'horizon'. You can turn off EWA
2731resampling, by specifing the special <a href="command-line-options.html#filter">-filter</a> setting of
2732'<code>point</code>' (recommended if you plan to use super-sampling instead).
2733</p>
2734
2735<p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
2736example, <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
2737what these pixels to be visible, set the color to match the rest of the
2738ground. </p>
2739
2740<p>The output image size will by default be the same as the input image. This
2741means that if the part of the distorted image falls outside the viewed area of
2742the 'distorted space', those parts is clipped and lost. However if you use
2743the plus form of the operator (<a href="command-line-options.html#distort">+distort</a>) the operator
2744will attempt (if possible) to show the whole of the distorted image, while
2745retaining a correct 'virtual canvas' offset, for image layering. This offset
2746may need to be removed using <a href="command-line-options.html#repage">+repage</a>, to remove if it
2747is unwanted. </p>
2748
2749<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,
2750and the <a href="command-line-options.html#fx">-fx</a> equivalent to the distortion, for expert study,
2751and debugging purposes. This many not be available for all distorts. </p>
2752
2753<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
2754specify the size and the offset of the generated 'viewport' image of the
2755distorted image space.</p>
2756
2757<p>Setting a "<code><a href="command-line-options.html#define">-define</a>
2758distort:scale={scale_factor}</code>" will scale the output image (viewport or
2759otherwise) by that factor without changing the viewed contents of the
2760distorted image. This can be used either for 'super-sampling' the image for
2761a higher quality result, or for panning and zooming around the image (with
2762appropriate viewport changes, or post-distort cropping and resizing). </p>
2763
2764<p>Setting "<code><a href="command-line-options.html#define">-define</a> resample:verbose=1</code>"
2765will output the cylindrical filter lookup table created by the EWA (Elliptical
2766Weighted Average) resampling algorithm. Note this table uses a squared radius
2767lookup value. This is typically only used for debugging EWA resampling. </p>
2768
2769
2770<div style="margin: auto;">
2771 <h4><a id="distribute-cache"></a>-distribute-cache <var>port</var></h4>
2772</div>
2773
2774<p class="magick-description">launch a distributed pixel cache server. </p>
2775
2776<div style="margin: auto;">
2777 <h4><a id="dither"></a>-dither <var>method</var></h4>
2778</div>
2779
2780<p class="magick-description">Apply a Riemersma or Floyd-Steinberg error diffusion dither to
2781images when general color reduction is applied via an option, or automagically
2782when saving to specific formats. This enabled by default.</p>
2783
2784<p>Dithering places two or more colors in neighboring pixels so that to the
2785eye a closer approximation of the images original color is reproduced. This
2786reduces the number of colors needed to reproduce the image but at the cost of
2787a lower level pattern of colors. Error diffusion dithers can use any set of
2788colors (generated or user defined) to an image. </p>
2789
2790<p>Dithering is turned on by default, to turn it off use the plus form of the
2791setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
2792without text or graphic aliasing. Disabling dithering often (but not always)
2793leads to faster process, a smaller number of colors, but more cartoon like
2794image coloring. Generally resulting in 'color banding' effects in areas with
2795color gradients. </p>
2796
2797<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
2798color set they created. These operators are also used as part of automatic
2799color reduction when saving images to formats with limited color support, such
2800as <code>GIF:</code>, <code>XBM:</code>, and others, so dithering may also be used
2801in these cases. </p>
2802
2803<p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
2804to generate purely random dither. Or use <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
2805patterns, using uniform color maps, rather than specific color maps. </p>
2806
2807
2808<div style="margin: auto;">
2809 <h4><a id="draw"></a>-draw <var>string</var></h4>
2810</div>
2811
2812<p class="magick-description">Annotate an image with one or more graphic primitives.</p>
2813
2814<p>Use this option to annotate or decorate an image with one or more graphic
2815primitives. The primitives include shapes, text, transformations, and pixel
2816operations.</p>
2817
2818<p>The shape primitives:</p>
2819
2820<pre>
2821 point x,y
2822 line x0,y0 x1,y1
2823 rectangle x0,y0 x1,y1
2824 roundRectangle x0,y0 x1,y1 wc,hc
2825 arc x0,y0 x1,y1 a0,a1
2826 ellipse x0,y0 rx,ry a0,a1
2827 circle x0,y0 x1,y1
2828 polyline x0,y0 ... xn,yn
2829 polygon x0,y0 ... xn,yn
2830 bezier x0,y0 ... xn,yn
2831 path path specification
2832 image operator x0,y0 w,h filename
2833</pre>
2834
2835<p>The text primitive:</p>
2836
2837<pre>
2838 text x0,y0 string
2839</pre>
2840<p>The text gravity primitive:</p>
2841
2842<pre>
2843 gravity NorthWest, North, NorthEast, West, Center,
2844 East, SouthWest, South, or SouthEast
2845</pre>
2846
2847<p>The text gravity primitive only affects the placement of text and does not
2848interact 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
2849scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
2850
2851<p>The transformation primitives:</p>
2852
2853<pre>
2854 rotate degrees
2855 translate dx,dy
2856 scale sx,sy
2857 skewX degrees
2858 skewY degrees
2859</pre>
2860
2861<p>The pixel operation primitives:</p>
2862
2863<pre>
2864 color x0,y0 method
2865 matte x0,y0 method
2866</pre>
2867
2868<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
2869"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>
2870
2871<p>A <code>point</code> primitive is specified by a single <var>point</var> in the
2872pixel plane, that is, by an ordered pair of integer coordinates,
2873<var>x</var>,<var>y</var>. (As it involves only a single pixel, a <code>point</code>
2874primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
2875
2876<p>A <code>line</code> primitive requires a start point and end point.</p>
2877
2878<p>A <code>rectangle</code> primitive is specified by the pair of points at the
2879upper left and lower right corners.</p>
2880
2881<p>A <code>roundRectangle</code> primitive takes the same corner points as
2882a <code>rectangle</code> followed by the width and height of the rounded corners
2883to be removed.</p>
2884
2885<p>The <code>circle</code> primitive makes a disk (filled) or circle (unfilled).
2886Give the center and any point on the perimeter (boundary).</p>
2887
2888<p>The <code>arc</code> primitive is used to inscribe an elliptical segment in
2889to a given rectangle. An <code>arc</code> requires the two corners used for
2890<code>rectangle</code> (see above) followed by the start and end angles of the
2891arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
2892points produced are then joined with a line segment and the resulting segment
2893of an ellipse is filled.</p>
2894
2895<p>Use <code>ellipse</code> to draw a partial (or whole) ellipse. Give the
2896center point, the horizontal and vertical "radii" (the <var>semi-axes</var> of
2897the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
28980,360).</p>
2899
2900<p>The <code>polyline</code> and <code>polygon</code> primitives require three or
2901more points to define their perimeters. A <code>polyline</code> is simply
2902a <code>polygon</code> in which the final point is not stroked to the start
2903point. 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
2904a <code>polyline</code> is identical to a <code>polygon</code>. </p>
2905
2906<p>A <var>coordinate</var> is a pair of integers separated by a space or
2907optional comma. </p>
2908
2909<p>As an example, to define a circle centered at 100,100 that extends to
2910150,150 use:</p>
2911
2912<p class="crtsnip">
2913 -draw 'circle 100,100 150,150'
2914</p>
2915
2916<p>The <code>Bezier</code> primitive creates a spline curve and requires three
2917or points to define its shape. The first and last points are the
2918<var>knots</var> and these points are attained by the curve, while any
2919intermediate coordinates are <var>control points</var>. If two control points
2920are specified, the line between each end knot and its sequentially respective
2921control point determines the tangent direction of the curve at that end. If
2922one control point is specified, the lines from the end knots to the one
2923control point determines the tangent directions of the curve at each end. If
2924more than two control points are specified, then the additional control points
2925act in combination to determine the intermediate shape of the curve. In order
2926to draw complex curves, it is highly recommended either to use the
2927<code>path</code> primitive or to draw multiple four-point bezier segments with
2928the start and end knots of each successive segment repeated. For example:</p>
2929
2930<p class="crtsnip">
2931 -draw 'bezier 20,50 45,100 45,0 70,50'
2932</p>
2933<p class="crtsnip">
2934 -draw 'bezier 70,50 95,100 95,0 120,50'
2935</p>
2936
2937
2938<p>A <code>path</code> represents an outline of an object, defined in terms of
2939moveto (set a new current point), lineto (draw a straight line), curveto (draw
2940a Bezier curve), arc (elliptical or circular arc) and closepath (close the
2941current shape by drawing a line to the last moveto) elements. Compound paths
2942(i.e., a path with subpaths, each consisting of a single moveto followed by
2943one or more line or curve operations) are possible to allow effects such as
2944<var>donut holes</var> in objects. (See <a href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
2945
2946<p>Use <code>image</code> to composite an image with another image. Follow the
2947image keyword with the composite operator, image location, image size, and
2948filename:</p>
2949
2950<p class="crtsnip">
2951 -draw 'image SrcOver 100,100 225,225 image.jpg'
2952</p>
2953
2954<p>You can use 0,0 for the image size, which means to use the actual
2955dimensions found in the image header. Otherwise, it is scaled to the given
2956dimensions. See <a href="compose.html">Alpha Compositing</a> for
2957a detailed discussion of alpha composition methods that are available. </p>
2958
2959<p>The "special augmented compose operators" such as "dissolve" that require
2960arguments cannot be used at present with the <code>-draw image</code> option.
2961 </p>
2962
2963<p>Use <code>text</code> to annotate an image with text. Follow the text
2964coordinates with a string. If the string has embedded spaces, enclose it in
2965single or double quotes.</p>
2966
2967<p>For example, the following annotates the image with <code>Works like
2968magick!</code> for an image titled <code>bird.miff</code>. </p>
2969
2970<p class="crtsnip">
2971 -draw "text 100,100 'Works like magick!' "
2972</p>
2973
2974<p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
2975to annotate an image with text.</p>
2976
2977<p>The <code>rotate</code> primitive rotates subsequent shape primitives and
2978text 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>
2979option, the origin for transformations is the upper left corner of the
2980region.</p>
2981
2982<p>The <code>translate</code> primitive translates subsequent shape and text
2983primitives.</p>
2984
2985<p>The <code>scale</code> primitive scales them.</p>
2986
2987<p>The <code>skewX</code> and <code>skewY</code> primitives skew them with respect
2988to the origin of the main image or the region.</p>
2989
2990<p>The transformations modify the current affine matrix, which is initialized
2991from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
2992option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
2993option. The initial affine matrix is not affected; that matrix is only changed
2994by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
2995<a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
2996reinitialized from the initial affine matrix.</p>
2997
2998<p>Use the <code>color</code> primitive to change the color of a pixel to the
2999fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
3000a method:</p>
3001
3002<pre>
3003 point
3004 replace
3005 floodfill
3006 filltoborder
3007 reset
3008</pre>
3009
3010<p>Consider the target pixel as that specified by your coordinate. The
3011<code>point</code> method recolors the target pixel. The <code>replace</code>
3012method recolors any pixel that matches the color of the target pixel.
3013<code>Floodfill</code> recolors any pixel that matches the color of the target
3014pixel and is a neighbor, whereas <code>filltoborder</code> recolors any neighbor
3015pixel that is not the border color. Finally, <code>reset</code> recolors all
3016pixels.</p>
3017
3018<p>Use <code>matte</code> to the change the pixel matte value to transparent.
3019Follow the pixel coordinate with a method (see the <code>color</code> primitive
3020for a description of methods). The <code>point</code> method changes the matte
3021value of the target pixel. The <code>replace</code> method changes the matte
3022value of any pixel that matches the color of the target pixel.
3023<code>Floodfill</code> changes the matte value of any pixel that matches the
3024color of the target pixel and is a neighbor, whereas <code>filltoborder</code>
3025changes 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
3026matte value of all pixels.</p>
3027
3028<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>
3029respectively. Options are processed in command line order so be sure to use
3030these options <var>before</var> the <a href="command-line-options.html#draw">-draw</a> option.</p>
3031
3032<p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
3033than 1.png).</p>
3034
3035<p>Drawing primitives conform to the <a href="magick-vector-graphics.html">Magick
3036Vector Graphics</a> format.</p>
3037
3038
3039<div style="margin: auto;">
3040 <h4><a id="duplicate"></a>-duplicate <var>count,indexes</var></h4>
3041</div>
3042
3043<p class="magick-description">duplicate an image one or more times.</p>
3044
3045<p>Specify the count and the image to duplicate by its index in the sequence.
3046The first image is index 0. Negative indexes are relative to the end of the
3047sequence, for example, -1 represents the last image of the sequence. Specify
3048a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g.
30490,2). Use <code>+duplicate</code> to duplicate the last image in the current
3050image sequence.</p>
3051
3052<div style="margin: auto;">
3053 <h4><a id="edge"></a>-edge <var>radius</var></h4>
3054</div>
3055
3056<p class="magick-description">detect edges within an image.</p>
3057
3058<div style="margin: auto;">
3059 <h4><a id="emboss"></a>-emboss <var>radius</var></h4>
3060</div>
3061
3062<p class="magick-description">emboss an image.</p>
3063
3064<div style="margin: auto;">
3065 <h4><a id="encipher"></a>-encipher <var>filename</var></h4>
3066</div>
3067
3068<p class="magick-description">Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</p>
3069
3070<p>Get the passphrase from the file specified by <var>filename</var>.</p>
3071
3072<p>For more information, see the webpage, <a href="../cipher.html">ImageMagick: Encipher or
3073Decipher an Image</a>.</p>
3074
3075
3076
3077<div style="margin: auto;">
3078 <h4><a id="encoding"></a>-encoding <var>type</var></h4>
3079</div>
3080
3081<p class="magick-description">specify the text encoding.</p>
3082
3083<p>Choose from <code>AdobeCustom</code>, <code>AdobeExpert</code>,
3084<code>AdobeStandard</code>, <code>AppleRoman</code>, <code>BIG5</code>,
3085<code>GB2312</code>, <code>Latin 2</code>, <code>None</code>, <code>SJIScode</code>,
3086<code>Symbol</code>, <code>Unicode</code>, <code>Wansung</code>.</p>
3087
3088<div style="margin: auto;">
3089 <h4><a id="endian"></a>-endian <var>type</var></h4>
3090</div>
3091
3092<p class="magick-description">Specify endianness (<code>MSB</code> or <code>LSB</code>) of the image.</p>
3093
3094<p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3095
3096<p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3097
3098
3099<div style="margin: auto;">
3100 <h4><a id="enhance"></a>-enhance</h4>
3101</div>
3102
3103<p class="magick-description">Apply a digital filter to enhance a noisy image.</p>
3104
3105
3106<div style="margin: auto;">
3107 <h4><a id="equalize"></a>-equalize</h4>
3108</div>
3109
3110<p class="magick-description">perform histogram equalization on the image channel-by-channel.</p>
3111
3112<p>To perform histogram equalization on all channels in concert, transform the
3113image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3114equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3115
3116<p>For example using HSL, we have: ... <code>-colorspace HSL -channel lightness
3117-equalize -colorspace RGB</code> ...</p>
3118
3119<p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3120components transformation that puts most of the information in the first
3121channel. Here we have ... <code>-colorspace OHTA -channel red -equalize
3122-colorspace RGB</code> ...</p>
3123
3124<div style="margin: auto;">
3125 <h4><a id="evaluate"></a>-evaluate <var>operator value</var></h4>
3126</div>
3127
3128<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</p>
3129
3130<p>(See the <a href="command-line-options.html#function">-function</a> operator for some
3131multi-parameter functions. See the <a href="command-line-options.html#fx">-fx</a> operator if more
3132elaborate calculations are needed.)</p>
3133
3134<p>The behaviors of each <var>operator</var> are summarized in the
3135following list. For brevity, the numerical value of a "pixel" referred to
3136below is the value of the corresponding channel of that pixel, while
3137a "normalized pixel" is that number divided by the maximum
3138(installation-dependent) value <var>QuantumRange</var>. (If
3139normalized pixels are used, they are restored, following the other
3140calculations, to the full range by multiplying by <var>QuantumRange</var>.)</p>
3141
3142<table class="table table-condensed table-striped">
3143 <col width="25%">
3144 <col width="75%">
3145 <thead>
3146 <tr>
3147 <th><var>operator</var></th>
3148 <th>Summary (see further below for details)</th>
3149 </tr>
3150 </thead>
3151 <tbody>
3152
3153 <tr><td>Abs </td> <td>Add <var>value</var> to pixels and return absolute value. </td></tr>
3154 <tr><td>Add </td> <td>Add <var>value</var> to pixels. </td></tr>
3155 <tr><td>AddModulus </td> <td>Add <var>value</var> to pixels modulo <var>QuantumRange</var>.</td></tr>
3156 <tr><td>And </td> <td>Binary AND of pixels with <var>value</var>.</td></tr>
3157 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3158 <tr><td>Divide </td> <td>Divide pixels by <var>value</var>.</td></tr>
3159 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
3160 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
3161 <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>
3162 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
3163 <tr><td>Max </td> <td>Clip pixels at lower bound <var>value</var>.</td></tr>
3164 <tr><td>Mean </td> <td>Add the <var>value</var> and divide by 2.</td></tr>
3165 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
3166 <tr><td>Min </td> <td>Clip pixels at upper bound <var>value</var>.</td></tr>
3167 <tr><td>Multiply </td> <td>Multiply pixels by <var>value</var>.</td></tr>
3168 <tr><td>Or </td> <td>Binary OR of pixels with <var>value</var>.</td></tr>
3169 <tr><td>Pow </td> <td>Raise normalized pixels to the power <var>value</var>.</td></tr>
3170 <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>
3171 <tr><td>RMS</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3172 <tr><td>RootMeanSquare</td> <td>Square the pixel and add the <var>value</var>.</td></tr>
3173 <tr><td>Set </td> <td>Set pixel equal to <var>value</var>.</td></tr>
3174 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <var>value</var> with 50% bias added.</td></tr>
3175 <tr><td>Subtract </td> <td>Subtract <var>value</var> from pixels.</td></tr>
3176 <tr><td>Xor </td> <td>Binary XOR of pixels with <var>value.</var></td></tr>
3177
3178 <tr><td> </td></tr>
3179
3180 <tr><td>Gaussian-noise</td></tr>
3181 <tr><td>Impulse-noise</td></tr>
3182 <tr><td>Laplacian-noise</td></tr>
3183 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise">-noise</a> operators.)</td></tr>
3184 <tr><td>PoissonNoise</td></tr>
3185 <tr><td>Uniform-noise</td></tr>
3186
3187 <tr><td> </td></tr>
3188
3189 <tr><td>Threshold </td> <td>Threshold pixels larger than <var>value</var>.</td></tr>
3190 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <var>value</var>.</td></tr>
3191 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <var>value</var>. </td></tr>
3192 </tbody>
3193 </table>
3194
3195<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
3196calculations are truncated (clipped) to fit in the interval [0, <var>QuantumRange</var>]. The transparency channel of the image is
3197represented as a 'alpha' values (0 = fully transparent), so, for example, a
3198<code>Divide</code> by 2 of the alpha channel will make the image
3199semi-transparent. Append the percent symbol '<code>%</code>' to specify a value
3200as a percentage of the <var>QuantumRange</var>.</p>
3201
3202<p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3203<a href="command-line-options.html#list">-list evaluate</a>.</p>
3204
3205<p>The results of the <code>Add</code>, <code>Subtract</code> and
3206<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
3207appropriate argument, to linearly modify the overall range of color values.
3208Please note, however, that <a href="command-line-options.html#level">-level</a> treats transparency as
3209'matte' values (0 = opaque), while <a href="command-line-options.html#level">-evaluate</a> works with
3210'alpha' values.</p>
3211
3212<p><code>AddModulus</code> has been added as of ImageMagick 6.4.8-4 and provides
3213addition modulo the <var>QuantumRange</var>. It is therefore
3214equivalent to <code>Add</code> unless the resulting pixel value is outside the
3215interval [0, <var>QuantumRange</var>]. </p>
3216
3217<p><code>Exp or Exponential</code> has been added as of ImageMagick 6.6.5-1 and
3218works on normalized pixel values. The <var>value</var> used with
3219<code>Exp</code> should be negative so as to produce a decaying exponential
3220function. Non-negative values will always produce results larger unity and
3221thus outside the interval [0, <var>QuantumRange</var>]. The
3222formula is expressed below. </p>
3223
3224 <div style="text-align:center;">
3225 exp(<var>value</var> × <b><var>u</var></b>)
3226 </div>
3227
3228<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
3229the result.</p>
3230
3231<p><code>Log</code> has been added as of ImageMagick 6.4.2-1 and works on
3232normalized pixel values. This a <var>scaled</var> log function. The <var>value</var> used with <code>Log</code> provides a <var>scaling
3233factor</var> that adjusts the curvature in the graph of the log function. The
3234formula applied to a normalized value <b><var>u</var></b> is below. </p>
3235
3236 <div style="text-align:center;">
3237 log(<var>value</var> × <b><var>u</var></b> + 1) / log(<var>value</var> + 1)
3238 </div>
3239
3240<p><code>Pow</code> has been added as of ImageMagick 6.4.1-9, and works on
3241normalized 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
3242to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3243with <a href="command-line-options.html#gamma">-gamma</a> is simply the reciprocal of the value used
3244with <code>Pow</code>.</p>
3245
3246<p><code>Cosine</code> and <code>Sine</code> was added as of IM v6.4.8-8 and
3247converts the image values into a value according to a (co)sine wave function.
3248The synonyms <code>Cos</code> and <code>Sin</code> may also be used. The output
3249is biased 50% and normalized by 50% so as to fit in the respective color value
3250range. The <var>value</var> scaling of the <var>period</var> of the
3251function (its frequency), and thus determines the number of 'waves' that will
3252be 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,
3253then the effective period is the <var>half</var> the <var>QuantumRange</var>.</p>
3254
3255 <div style="text-align:center;">
3256 0.5 + 0.5 × cos(2 π <b><var>u</var></b> × <var>value</var>).
3257 </div>
3258
3259<p>See also the <a href="command-line-options.html#function">-function</a> operator, which is a
3260multi-value version of evaluate. </p>
3261
3262<div style="margin: auto;">
3263 <h4><a id="evaluate-sequence"></a>-evaluate-sequence <var>operator</var></h4>
3264</div>
3265
3266<p class="magick-description">Alter channel pixels by evaluating an arithmetic, relational, or
3267logical expression over a sequence of images.</p>
3268
3269<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>
3270
3271<div style="margin: auto;">
3272 <h4><a id="extent"></a>-extent <var>geometry</var></h4>
3273</div>
3274
3275<p class="magick-description">Set the image size and offset.</p>
3276
3277<p>If the image is enlarged, unfilled areas are set to the background color.
3278To position the image, use offsets in the <var>geometry</var>
3279specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting. To
3280specify how to compose the image with the background, use <a href="command-line-options.html#compose">-compose</a>.</p>
3281
3282<p>This command reduces or expands a JPEG image to fit on an 800x600
3283display. If the aspect ratio of the input image isn't exactly 4:3, then the
3284image is centered on an 800x600 black canvas: </p>
3285
3286<pre>
3287convert input.jpg -resize 800x600 -background black -compose Copy \
3288 -gravity center -extent 800x600 -quality 92 output.jpg
3289</pre>
3290
3291<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3292
3293<div style="margin: auto;">
3294 <h4><a id="extract"></a>-extract <var>geometry</var></h4>
3295</div>
3296
3297<p class="magick-description">Extract the specified area from image.</p>
3298
3299<p>This option is most useful for extracting a subregion of a very large raw
3300image. Note that these two commands are equivalent:</p>
3301
3302<pre>
3303convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \
3304 image.rgb image.png",
3305convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \
3306 image.rgb image.png"
3307</pre>
3308
3309<p>If you omit the offsets, as in</p>
3310
3311<pre>
3312convert -size 16000x16000 -depth 8 -extract 640x480 \
3313 image.rgb image.png
3314</pre>
3315
3316<p>the image is <var>resized</var> to the specified dimensions instead,
3317equivalent to:</p>
3318
3319<pre>
3320convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png
3321</pre>
3322
3323<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3324
3325<div style="margin: auto;">
3326 <h4><a id="family"></a>-family <var>fontFamily</var></h4>
3327</div>
3328
3329<p class="magick-description">Set a font family for text.</p>
3330
3331<p>This setting suggests a font family that ImageMagick should try to use for
3332rendering text. If the family can be found it is used; if not, a default font
3333(e.g., "Arial") or a family known to be similar is substituted (e.g.,
3334"Courier" might be used if "System" is requested but not found). </p>
3335
3336<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>
3337
3338<div style="margin: auto;">
3339 <h4><a id="features"></a>-features <var>distance</var></h4>
3340</div>
3341
3342<p class="magick-description">display (cooccurrence matrix) texture measure features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance.</p>
3343
3344<pre>
3345 Angular Second Moment
3346 Contrast
3347 Correlation
3348 Sum of Squares Variance
3349 Inverse Difference Moment
3350 Sum Average
3351 Sum Variance
3352 Sum Entropy
3353 Entropy
3354 Difference Variance
3355 Difference Entropy
3356 Information Measure of Correlation 1
3357 Information Measure of Correlation 2
3358 Maximum Correlation Coefficient
3359</pre>
3360
3361
3362<div style="margin: auto;">
3363 <h4><a id="fft"></a>-fft</h4>
3364</div>
3365
3366<p class="magick-description">implements the forward discrete Fourier transform (DFT).</p>
3367
3368<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3369users in ImageMagick 6.6.0-9). It transforms an image from the normal
3370(spatial) domain to the frequency domain. In the frequency domain, an image is
3371represented as a superposition of complex sinusoidal waves of varying
3372amplitudes. The image x and y coordinates are the possible frequencies along
3373the x and y directions, respectively, and the pixel intensity values are
3374complex numbers that correspond to the sinusoidal wave amplitudes. See for
3375example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3376Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3377Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3378Transform</a>.</p>
3379
3380<p>A single image name is provided as output for this option. However, the
3381output result will have two components. It is either a two-frame image or two
3382separate images, depending upon whether the image format specified supports
3383multi-frame images. The reason that we get a dual output result is because the
3384frequency domain represents an image using complex numbers, which cannot be
3385visualized directly. Therefore, the complex values are automagically separated
3386into a two-component image representation. The first component is the
3387magnitude of the complex number and the second is the phase of the complex
3388number. See for example, <a href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3389
3390<p>The magnitude and phase component images must be specified using image
3391formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3392PFM, EXR and PNG are the recommended image formats to use. All of these
3393formats, except PNG support multi-frame images. So for example,</p>
3394
3395<pre>
3396convert image.png -fft fft_image.miff
3397</pre>
3398
3399<p>generates a magnitude image as <code>fft_image.miff[0]</code> and a phase
3400image as <code>fft_image.miff[1]</code>. Similarly,</p>
3401
3402<pre>
3403convert image.png -fft fft_image.png
3404</pre>
3405
3406<p>generates a magnitude image as <code>fft_image-0.png</code> and a phase image
3407as <code>fft_image-1.png</code>. If you prefer this representation, then you can
3408force 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>
3409
3410<p>The input image can be any size, but if not square and even-dimensioned, it
3411is padded automagically to the larger of the width or height of the input
3412image and to an even number of pixels. The padding will occur at the bottom
3413and/or right sides of the input image. The resulting output magnitude and
3414phase 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>
3415
3416<p>Both output components will have dynamic ranges that fit within
3417[0, <var>QuantumRange</var>], so that HDRI need not be enabled.
3418Phase values nominally range from 0 to 2*π, but is scaled to span the full
3419dynamic range. (The first few releases had non-HDRI scaled but HDRI not
3420scaled). The magnitude image is not scaled and thus generally will contain
3421very small values. As such, the image normally will appear totally black. In
3422order to view any detail, the magnitude image typically is enhanced with a log
3423function into what is usually called the spectrum. A log function is used to
3424enhance the darker values more in comparison to the lighter values. This can
3425be done, for example, as follows:</p>
3426
3427<pre>
3428convert fft_image.miff[0] -contrast-stretch 0 \
3429 -evaluate log 1000 fft_image_spectrum.png"
3430</pre>
3431
3432<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
3433range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3434typically is specified between 100 and 10,000, depending upon the amount of
3435detail that one wants to bring out in the spectrum. Larger values produce more
3436visible detail. Too much detail, however, may hide the important features.</p>
3437
3438<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3439use <a href="command-line-options.html#fft">-fft</a>.</p>
3440
3441<p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3442and imaginary components of the complex valued Fourier transform.</p>
3443
3444<p>However, as the real and imaginary components can contain negative values,
3445this requires that IM be configured with HDRI enabled. In this case, you must
3446use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3447results, since they are formats that preserve both negative and fractional
3448values without clipping them or truncating the fractional part. With either
3449MIFF or TIF, one should add -define quantum:format=32, to allow those image
3450types to work properly in HDRI mode without clipping.</p>
3451
3452<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
3453padding that was discussed above for the magnitude and phase component
3454images.</p>
3455
3456<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
3457about 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>
3458 entry. </p>
3459
3460<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 explicityly normalize the FFT and unnormalize the IFT.</p>
3461
3462
3463<div style="margin: auto;">
3464 <h4><a id="fill"></a>-fill <var>color</var></h4>
3465</div>
3466
3467<p class="magick-description">color to use when filling a graphic primitive.</p>
3468
3469<p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3470HSL, HSLA, CMYK, or CMYKA specification. See <a href="color.html">Color Names</a> for
3471a description of how to properly specify the color argument.</p>
3472
3473<p>Enclose the color specification in quotation marks to prevent the "#" or
3474the parentheses from being interpreted by your shell.</p>
3475
3476<p>For example,</p>
3477
3478<p class="crtsnip">
3479 -fill blue
3480</p>
3481<p class="crtsnip">
3482 -fill "#ddddff"
3483</p>
3484<p class="crtsnip">
3485 -fill "rgb(255,255,255)"
3486</p>
3487
3488<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3489
3490<p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3491
3492<div style="margin: auto;">
3493 <h4><a id="filter"></a>-filter <var>type</var></h4>
3494</div>
3495
3496<p class="magick-description">Use this <var>type</var> of filter when resizing or distorting an image.</p>
3497
3498<p>Use this option to affect the resizing operation of an image during
3499operations 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>
3500
3501<pre>
3502 Point Hermite Cubic
3503 Box Gaussian Catrom
3504 Triangle Quadratic Mitchell
3505</pre>
3506
3507<p>The <code>Bessel</code> and <code>Sinc</code> filter is also provided (as well
3508as a faster <code>SincFast</code> equivalent form). However these filters are
3509generally useless on their own as they are infinite filters that are being
3510clipped to the filters support size. Their direct use is not recommended
3511except via expert settings (see below). </p>
3512
3513<p>Instead these special filter functions are typically windowed by a windowing
3514function that the <a href="command-line-options.html#filter">-filter</a> setting defines. That is
3515using these functions will define a 'Windowed' filter, appropriate to the
3516operator involved. Windowed filters include: </p>
3517
3518<pre>
3519 Lanczos Hamming Parzen
3520 Blackman Kaiser Welsh
3521 Hanning Bartlett Bohman
3522</pre>
3523
3524<p>Also one special self-windowing filter is also provided
3525<code>Lagrange</code>, which will automagically re-adjust its function depending
3526on the current 'support' or 'lobes' expert settings (see below).</p>
3527
3528<p>If you do not select a filter with this option, the filter defaults to
3529<code>Mitchell</code> for a colormapped image, an image with a matte channel, or
3530if the image is enlarged. Otherwise the filter default to
3531<code>Lanczos</code>.</p>
3532
3533<p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3534filter</a> option.</p>
3535
3536<p>You can modify how the filter behaves as it scales your image through the
3537use 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>
3538
3539<dl>
3540<dt>-define filter:blur=<var>factor</var></dt>
3541<dd>Scale the X axis of the filter (and its window). Use &gt; 1.0 for
3542 blurry or &lt; 1.0 for sharp. This should only be used with Gaussian and
3543 Gaussian-like filters simple filters, or you may not get the expected
3544 results. </dd>
3545
3546<dt>-define filter:support=<var>radius</var></dt>
3547<dd>Set the filter support radius. Defines how large the filter should be and
3548 thus directly defines how slow the filtered resampling process is. All
3549 filters have a default 'prefered' support size. Some filters like
3550 <code>Lagrange</code> and windowed filters adjust themselves depending on
3551 this value. With simple filters this value either does nothing (but slow
3552 the resampling), or will clip the filter function in a detrimental way.
3553 </dd>
3554
3555<dt>-define filter:lobes=<var>count</var></dt>
3556<dd>Set the number of lobes to use for the Sinc/Bessel filter. This an
3557 alternative way of specifying the 'support' range of the filter, that is
3558 designed to be more suited to windowed filters, especially when used for
3559 image distorts.</dd>
3560
3561<dt>-define filter:sigma=<var>value</var></dt>
3562<dd>The 'sigma' value used to define the <code>Gaussian</code> filter. Default
3563 sigma value is '<code>0.5</code>'. It only effects <code>Gaussian</code> but
3564 does not shrink (but may enlarge) the filter's 'support'. It can be used
3565 to generate very small blurs but without the filter 'missing' pixels due
3566 to using a small support setting. A larger value of '<code>0.707</code>'
3567 (a value of '1/sqrt(2)') is another common setting. </dd>
3568
3569<dt>-define filter:b=<var>b-spline_factor</var></dt>
3570<dt>-define filter:c=<var>keys_alpha_factor</var></dt>
3571<dd>Redefine the values used for cubic filters such as <code>Cubic</code>,
3572 <code>Catrom</code>, <code>Mitchel</code>, and <code>Hermite</code>, as well as
3573 the <code>Parzen</code> cubic windowing function. If only one of the values
3574 are defined, the other is set so as to generate a 'Cubic-Keys' filter.
3575 The values meaning was defined by a research paper by
3576 Mitchell-Netravali.</dd>
3577
3578<dt>-define filter:kaiser-beta=<var>value</var></dt>
3579<dd>The 'alpha' value used to as part of the Kaiser Windowing function.
3580 Default value is '6.5'. It only effects Kaiser windowing function, and
3581 does not effect any other attributes.</dd>
3582
3583<dd>Before IM v6.7.6-10, this option was known as "filter:alpha", (an
3584 inheritance from the very old "zoom" program). It was changed to bring the
3585 function in line with more modern academic research usage, and better
3586 assign it be more definitive. </dd>
3587
3588<dt>-define filter:kaiser-alpha=<var>value</var></dt>
3589<dd>This value when multiplied by 'PI' is equivalent to "kaiser-beta", and
3590 will override that setting. It only effects Kaiser windowing function,
3591 and does not effect any other attributes. </dd>
3592
3593<dt>-define filter:filter=<var>filter_function</var></dt>
3594<dd>Use this function directly as the weighting filter. This will allow
3595 you to directly use a windowing function such as <code>Blackman</code>,
3596 as a resampling filter, rather than as its normal usage as a windowing
3597 function. </dd>
3598
3599<dd>If defined, no windowing function also defined, the window function is set
3600 to <code>Box</code>). Directly specifying <code>Sinc</code> or <code>Jinc</code>
3601 as a filter will also do this. </dd>
3602
3603<dt>-define filter:window=<var>filter_function</var></dt>
3604<dd>The IIR (infinite impulse response) filters <code>Sinc</code> and
3605 <code>Jinc</code> are windowed (brought down to zero over the defined
3606 support range) with the given filter. This allows you to specify a filter
3607 function to be used as a windowing function for these IIR filters. </dd>
3608
3609<dd>Many of the defined filters are actually windowing functions for these IIR
3610 filters. A typical choices is <code>Box</code>, (which effectively turns
3611 off the windowing function). </dd>
3612
3613<dt>-define filter:win-support=<var>radius</var></dt>
3614<dd>Scale windowing function to this size instead. This causes the windowing
3615 (or self-windowing Lagrange filter) to act is if the support window is
3616 larger than what is actually supplied to the calling operator. The filter
3617 however is still clipped to the real support size given. If unset this
3618 will equal the normal filter support size. </dd>
3619
3620<dt>-define filter:verbose=<var>1</var></dt>
3621<dd>This causes IM to print information on the final internal filter
3622 selection to standard output. This includes a commented header on the
3623 filter settings being used, and data allowing the filter weights to be
3624 easily graphed. </dd>
3625
3626<dd>Note however that some filters are internally defined in terms of other
3627 filters. The <code>Lanczos</code> filter for example is defined in terms of
3628 a <code>SincFast</code> windowed <code>SincFast</code> filter, while
3629 <code>Mitchell</code> is defined as a general <code>Cubic</code> family filter
3630 with specific 'B' and 'C' settings. </dd>
3631
3632</dl>
3633
3634<p>For example, to get a 8 lobe jinc windowed sinc filter (Genseng filter?):</p>
3635
3636<pre>
3637convert image.png \
3638 -filter sinc \
3639 -set filter:window=jinc \
3640 -set filter:lobes=8 \
3641 -resize 150% image.jpg"
3642</pre>
3643
3644<p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
3645
3646<pre>
3647convert image.png \
3648 -set filter:filter=sinc \
3649 -set filter:lobes=4 \
3650 -resize 150% image.jpg"
3651</pre>
3652
3653<p>To extract the data for a raw windowing function, combine it with
3654a '<code>Box</code>' filter. For example the '<code>Welch</code> parabolic
3655windowing function. </p>
3656
3657<pre>
3658convert null: -define filter:filter=Box \
3659 -define filter:window=Welch \
3660 -define filter:support=1.0 \
3661 -define filter:verbose=1 \
3662 -resize 2 null: &gt; window_welch.dat
3663gnuplot
3664 set grid
3665 plot \"window_welch.dat\" with lines
3666</pre>
3667
3668<p>Note that the use of expert options is provided for image processing experts
3669who have studied and understand how resize filters work. Without this
3670knowledge, and an understanding of the definition of the actual filters
3671involved, using expert settings are more likely to be detrimental to your image
3672resizing.</p>
3673
3674
3675<div style="margin: auto;">
3676 <h4><a id="flatten"></a>-flatten</h4>
3677</div>
3678
3679<p class="magick-description">This is a simple alias for the <a href="command-line-options.html#layers">-layers</a> method "flatten".</p>
3680
3681
3682<div style="margin: auto;">
3683 <h4><a id="flip"></a>-flip</h4>
3684</div>
3685
3686<p class="magick-description">create a <var>mirror image</var></p>
3687
3688<p>reflect the scanlines in the vertical direction. The image will be mirrored
3689upside-down. </p>
3690
3691
3692<div style="margin: auto;">
3693 <h4><a id="floodfill"></a>-floodfill {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var> <var>color</var></h4>
3694</div>
3695
3696<p class="magick-description">floodfill the image with color at the specified offset.</p>
3697
3698<p>Flood fill starts from the given 'seed point' which is not gravity effected.
3699Any color that matches within <a href="command-line-options.html#fuzz">-fuzz</a> color distance of the
3700given <var>color</var> argument, connected to that 'seed point'
3701will be replaced with the current <a href="command-line-options.html#fill">-fill</a> color. </p>
3702
3703<p>Note that if the pixel at the 'seed point' does not itself match the given
3704<var>color</var> (according to <a href="command-line-options.html#fuzz">-fuzz</a>), then no
3705action will be taken. </p>
3706
3707<p>This operator works more like the <a href="command-line-options.html#opaque">-opaque</a> option, than
3708a more general flood fill that reads the matching color directly at the 'seed
3709point'. For this form of flood fill, look at <a href="command-line-options.html#draw">-draw</a> and
3710its 'color floodfill' drawing method. </p>
3711
3712
3713<div style="margin: auto;">
3714 <h4><a id="flop"></a>-flop</h4>
3715</div>
3716
3717<p class="magick-description">create a <var>mirror image</var>.</p>
3718
3719<p>Reflect the scanlines in the horizontal direction, just like the image in
3720a vertical mirror. </p>
3721
3722
3723<div style="margin: auto;">
3724 <h4><a id="font"></a>-font <var>name</var></h4>
3725</div>
3726
3727<p class="magick-description">set the font to use when annotating images with text, or creating labels.</p>
3728
3729<p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
3730option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
3731
3732<p>In addition to the fonts specified by the above pre-defined list, you can
3733also specify a font from a specific source. For example <code>Arial.ttf</code>
3734is a TrueType font file, <code>ps:helvetica</code> is PostScript font, and
3735<code>x:fixed</code> is X11 font.</p>
3736
3737<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>
3738
3739
3740<div style="margin: auto;">
3741 <h4><a id="foreground"></a>-foreground <var>color</var></h4>
3742</div>
3743
3744<p class="magick-description">Define the foreground color for menus.", "display</p>
3745
3746<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
3747
3748<p>The default foreground color is black.</p>
3749
3750<div style="margin: auto;">
3751 <h4><a id="format"></a>-format <var>type</var></h4>
3752</div>
3753
3754<p class="magick-description">the image format type.</p>
3755
3756<p>When used with the <code>mogrify</code> utility, this option converts any
3757image to the image <a href="formats.html">format</a> you specify.
3758For a list of image format types supported by ImageMagick, use <a href="command-line-options.html#list">-list format</a>.</p>
3759
3760<p>By default the file is written to its original name. However, if the
3761filename extension matches a supported format, the extension is replaced with
3762the image format type specified with <a href="command-line-options.html#format">-format</a>. For
3763example, if you specify <var>tiff</var> as the format type and the
3764input image filename is <var>image.gif</var>, the output image
3765filename becomes <var>image.tiff</var>.</p>
3766
3767<div style="margin: auto;">
3768 <h4><a id="format_identify_"></a>-format <var>string</var></h4>
3769</div>
3770
3771<p class="magick-description">output formatted image characteristics.</p>
3772
3773<p>See <a href="escape.html">Format and Print Image
3774Properties</a> for an explanation on how to specify the argument to this
3775option.</p>
3776
3777<div style="margin: auto;">
3778 <h4><a id="frame"></a>-frame <var>geometry</var></h4>
3779</div>
3780
3781<p class="magick-description">Surround the image with a border or beveled frame.</p>
3782
3783<p>The color of the border is specified with the <a href="command-line-options.html#mattecolor">-mattecolor</a> command line option. </p>
3784
3785<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
3786height that is added to the dimensions of the image. If no offsets are given
3787in the <var>geometry</var> argument, then the border added is
3788a solid color. Offsets <var>x</var> and <var>y</var>, if present, specify that
3789the width and height of the border is partitioned to form an outer bevel of
3790thickness <var>x</var> pixels and an inner bevel of thickness
3791<var>y</var> pixels. Negative offsets make no sense as frame arguments.
3792</p>
3793
3794<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
3795'<code>Over</code>' composition method. It generates an image of the appropriate
3796size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
3797draws 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
3798center of this image. This means that with the default compose method of
3799'<code>Over</code>' any transparent parts may be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
3800
3801<p>The image composition is not
3802affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
3803
3804
3805<div style="margin: auto;">
3806 <h4><a id="frame_import_"></a>-frame</h4>
3807</div>
3808
3809<p class="magick-description">include the X window frame in the imported image. </p>
3810<div style="margin: auto;">
3811 <h4><a id="function"></a>-function <var>function</var> <var>parameters</var></h4>
3812</div>
3813
3814<p class="magick-description">Apply a function to channel values.</p>
3815
3816<p>This operator performs calculations based on the given arguments to modify
3817each 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
3818calculations are handled.</p>
3819
3820<p>This is can be considered a multi-argument version of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
3821ImageMagick 6.4.8−8.)</p>
3822
3823<p>Here, <var>parameters</var> is a comma-separated list of
3824numerical values. The number of values varies depending on which <var>function</var> is selected. Choose the <var>function</var> from:</p>
3825
3826<pre>
3827 Polynomial
3828 Sinusoid
3829 Arcsin
3830 Arctan
3831</pre>
3832
3833<p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
3834use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
3835
3836<dl>
3837<dt><code>Polynomial</code></dt>
3838<dd>
3839
3840<p>The <code>Polynomial</code> function takes an arbitrary number of parameters,
3841these being the coefficients of a polynomial, in decreasing order of degree.
3842That is, entering</p>
3843
3844<div style="text-align: center">
3845 -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>
3846</div>
3847
3848<p>will invoke a polynomial function given by</p>
3849
3850<div style="text-align: center">
3851 <var>a</var><sub><var>n</var></sub> <b><var>u</var></b><sup><var>n</var></sup> +
3852 <var>a</var><sub><var>n</var>-1</sub> <b><var>u</var></b><sup><var>n</var>-1</sup> +
3853 ··· <var>a</var><sub>1</sub> <b><var>u</var></b> + <var>a</var><sub>0</sub>,
3854</div>
3855
3856<p>where <b><var>u</var></b> is pixel's original normalized channel value.</p>
3857
3858<p>The <code>Polynomial</code> function can be used in place of <code>Set</code>
3859(the <var>constant</var> polynomial) and <code>Add</code>, <code>Divide</code>,
3860<code>Multiply</code>, and <code>Subtract</code> (some <var>linear</var>
3861polynomials) 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
3862correspondences follow.</p>
3863
3864<table class="table table-condensed table-striped">
3865 <col width="35%">
3866 <col width="35%">
3867 <col width="30%">
3868 <tr>
3869 <td>-evaluate Set <var>value</var> </td>
3870 <td>-function Polynomial <var>value</var></td>
3871 <td>(Constant functions; set <var>value</var>×100% gray when channels are RGB.)</td>
3872 </tr>
3873 <tr>
3874 <td>-evaluate Add <var>value</var> </td>
3875 <td>-function Polynomial 1,<var>value</var></td>
3876 </tr>
3877 <tr>
3878 <td>-evaluate Subtract <var>value</var> </td>
3879 <td>-function Polynomial 1,−<var>value</var></td>
3880 </tr>
3881 <tr>
3882 <td>-evaluate Multiply <var>value</var> </td>
3883 <td>-function Polynomial <var>value</var>,0</td>
3884 </tr>
3885 <tr>
3886 <td>+level black% x white%</td>
3887 <td>-function Polynomial A,B</td>
3888 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
3889 </tr>
3890</table>
3891
3892<p>The <code>Polynomial</code> function gives great versatility, since
3893polynomials can be used to fit any continuous curve to any degree of accuracy
3894desired.</p>
3895
3896</dd>
3897
3898<dt><code>Sinusoid</code></dt>
3899<dd>
3900<p>The <code>Sinusoid</code> function can be used to vary the channel values
3901sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
3902values are given as one to four parameters, as follows,</p>
3903
3904<div style="text-align: center">
3905 -function <code>Sinusoid</code> <var>freq</var>,[<var>phase</var>,[<var>amp</var>,[<var>bias</var>]]]
3906</div>
3907
3908<p>where <var>phase</var> is in degrees. (The domain [0,1] of the function
3909corresponds to 0 through <var>freq</var>×360 degrees.)
3910The result is that if a pixel's normalized channel value is originally
3911<b><var>u</var></b>, its resulting normalized value is given by </p>
3912
3913<div style="text-align: center">
3914<var>amp</var> * sin(2*π* (<var>freq</var> * <b><var>u</var></b> + <var>phase</var> / 360)) + <var>bias</var>
3915</div>
3916
3917<p> For example, the following generates a curve that starts and ends at 0.9
3918(when <b><var>u</var></b>=0 and 1, resp.), oscillating three times between
3919.7−.2=.5 and .7+.2=.9. </p>
3920
3921<p class="crtsnip">
3922 -function Sinusoid 3,-90,.2,.7
3923</p>
3924
3925<p>The default values of <var>amp</var> and <var>bias</var> are both .5. The default for <var>phase</var>
3926is 0.</p>
3927
3928<p>The <code>Sinusoid</code> function generalizes <code>Sin</code> and
3929<code>Cos</code> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
3930varying amplitude, phase and bias. The correspondence is as follows.</p>
3931
3932<table class="table table-condensed table-striped">
3933 <tr>
3934 <td>-evaluate Sin <var>freq</var> </td>
3935 <td>-function Sinusoid <var>freq</var>,0 </td>
3936 </tr>
3937 <tr>
3938 <td>-evaluate Cos <var>freq</var> </td>
3939 <td>-function Sinusoid <var>freq</var>,90 </td>
3940 </tr>
3941</table>
3942</dd>
3943
3944<dt><code>ArcSin</code></dt>
3945<dd>
3946<p>The <code>ArcSin</code> function generates the inverse curve of a Sinusoid,
3947and can be used to generate cylindrical distortion and displacement maps.
3948The curve can be adjusted relative to both the input values and output range
3949of values.</p>
3950
3951<p style="text-align: center">
3952 -function <code>ArcSin</code> <var>width</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
3953</p>
3954
3955<p>with all values given in terms of normalized color values (0.0 for black,
39561.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
3957for bout input (<var>width</var>), and output (<var>width</var>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
3958
3959<p style="text-align: center">
3960<var>range</var>/π * asin( 2/<var>width</var> * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
3961</p>
3962
3963</dd>
3964
3965<dt><code>ArcTan</code></dt>
3966<dd>
3967<p>The <code>ArcTan</code> function generates a curve that smooth crosses from
3968limit values at infinities, though a center using the given slope value.
3969All these values can be adjusted via the arguments.</p>
3970
3971<p style="text-align: center">
3972 -function <code>ArcTan</code> <var>slope</var>,[<var>center</var>,[<var>range</var>,[<var>bias</var>]]]
3973</p>
3974
3975<p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
3976</p>
3977
3978<p style="text-align: center">
3979<var>range</var>/π * atan( <var>slope</var>*π * ( <b><var>u</var></b> - <var>center</var> ) ) + <var>bias</var>
3980</p>
3981
3982</dd>
3983
3984</dl>
3985
3986
3987<div style="margin: auto;">
3988 <h4><a id="fuzz"></a>-fuzz <var>distance</var>{<var>%</var>}</h4>
3989</div>
3990
3991<p class="magick-description">Colors within this <var>distance</var> are considered equal.</p>
3992
3993<p>A number of algorithms search for a target color. By default the color must
3994be exact. Use this option to match colors that are close to the target color
3995in RGB space. For example, if you want to automagically trim the edges of an
3996image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
3997background color may differ by a small amount. This option can account for
3998these differences.</p>
3999
4000<p>The <var>distance</var> can be in absolute intensity units or, by
4001appending <code>%</code> as a percentage of the maximum possible intensity (255,
400265535, or 4294967295).</p>
4003
4004<p>Use <a href="command-line-options.html#fuzz">+fuzz</a> to reset the fuzz value to 0.</p>
4005
4006
4007<div style="margin: auto;">
4008 <h4><a id="fx"></a>-fx <var>expression</var></h4>
4009</div>
4010
4011<p class="magick-description">apply a mathematical expression to an image or image channels.</p>
4012
4013<p>If the first character of <var>expression</var> is <code>@</code>,
4014the expression is read from a file titled by the remaining characters in the
4015string.</p>
4016
4017<p>See <a href="fx.html">FX,
4018The Special Effects Image Operator</a> for a detailed discussion of this
4019option.</p>
4020
4021
4022<div style="margin: auto;">
4023 <h4><a id="gamma"></a>-gamma <var>value</var></h4>
4024</div>
4025
4026<p class="magick-description">level of gamma correction.</p>
4027
4028<p>The same color image displayed on two different workstations may look
4029different due to differences in the display monitor. Use gamma correction to
4030adjust for this color difference. Reasonable values extend from
4031<code>0.8</code> to <code>2.3</code>. Gamma less than 1.0 darkens the image and
4032gamma greater than 1.0 lightens it. Large adjustments to image gamma may
4033result in the loss of some image information if the pixel quantum size is only
4034eight bits (quantum range 0 to 255).</p>
4035
4036<p>Gamma adjusts the image's channel values pixel-by-pixel according to
4037a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
4038normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
4039same as taking the square root of the image.</p>
4040
4041<p>You can apply separate gamma values to the red, green, and blue channels of
4042the image with a gamma value list delimited with commas (e.g.,
4043<code>1.7,2.3,1.2</code>).</p>
4044
4045<p>Use <a href="command-line-options.html#gamma">+gamma <var>value</var></a> to set the
4046image gamma level without actually adjusting the image pixels. This option
4047is useful if the image is of a known gamma but not set as an image attribute
4048(e.g. PNG images). Write the "file gamma" which is the reciprocal of the
4049display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
4050chunk, use</p>
4051
4052<pre>
4053convert input.png +gamma .45455 output.png
4054</pre>
4055
4056<p>(0.45455 is 1/2.2)</p>
4057
4058<p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
4059
4060<div style="margin: auto;">
4061 <h4><a id="gaussian-blur"></a>-gaussian-blur <var>radius</var><br>-gaussian-blur <var>radius</var>x<var>sigma</var></h4>
4062</div>
4063
4064<p class="magick-description">Blur the image with a Gaussian operator.</p>
4065
4066<p>Convolve the image with a Gaussian or normal distribution using the given
4067<var>Sigma</var> value. The formula is:</p>
4068
4069<div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png">
4070</div>
4071
4072<p>The <var>Sigma</var> value is the important argument, and
4073determines the actual amount of blurring that will take place. </p>
4074
4075<p>The <var>Radius</var> is only used to determine the size of the
4076array which will hold the calculated Gaussian distribution. It should be an
4077integer. If not given, or set to zero, IM will calculate the largest possible
4078radius that will provide meaningful results for the Gaussian distribution.
4079</p>
4080
4081<p>The larger the <var>Radius</var> the radius the slower the
4082operation is. However too small a <var>Radius</var>, and sever
4083aliasing effects may result. As a guideline, <var>Radius</var>
4084should be at least twice the <var>Sigma</var> value, though three
4085times will produce a more accurate result. </p>
4086
4087<p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4088full 2-dimensional convolution is used to generate the weighted average of the
4089neighboring pixels. </p>
4090
4091<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4092pixels which are outside the image proper are blurred into the final result.
4093</p>
4094
4095
4096<div style="margin: auto;">
4097 <h4><a id="geometry"></a>-geometry <var>geometry</var></h4>
4098</div>
4099
4100<p class="magick-description">Set the preferred size and location of the image.</p>
4101
4102<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4103
4104<div style="margin: auto;">
4105 <h4><a id="gravity"></a>-gravity <var>type</var></h4>
4106</div>
4107
4108<p class="magick-description">Sets the current gravity suggestion for various other settings and options.</p>
4109
4110<p>Choices include: <code>NorthWest</code>, <code>North</code>,
4111<code>NorthEast</code>, <code>West</code>, <code>Center</code>, <code>East</code>,
4112<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
4113installation.</p>
4114
4115<p>The direction you choose specifies where to position text or subimages. For
4116example, a gravity of <code>Center</code> forces the text to be centered within
4117the 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
4118text 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>
4119
4120<p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4121<a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4122take <var>geometry</var> as an argument, such as the <a href="command-line-options.html#crop">-crop</a> option. </p>
4123
4124<p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4125or setting having a <var>geometry</var> argument that specifies an
4126offset, the offset is usually applied to the point within the image suggested
4127by the <a href="command-line-options.html#gravity">-gravity</a> argument. Thus, in the following
4128command, for example, suppose the file <code>image.png</code> has dimensions
4129200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4130is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4131<code>Center</code>, which suggests the midpoint of the image, at the point
4132(100,50). The offset (−40,20) is applied to that point, giving
4133(100−40,50+20)=(60,70), so the specified 10x10 region is located at
4134that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4135region itself, which is <var>centered</var> at the pixel
4136coordinate (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>
4137
4138<pre>
4139convert image.png -gravity Center -region 10x10-40+20 \
4140 -negate output.png
4141</pre>
4142
4143<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
4144within the composite.</p>
4145
4146<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
4147within a tile. The default gravity is <code>Center</code> for this purpose.</p>
4148
4149
4150<div style="margin: auto;">
4151 <h4><a id="grayscale"></a>-grayscale <var>method</var></h4>
4152</div>
4153
4154<p class="magick-description">convert image to grayscale.</p>
4155
4156<p>This will use one of the <a href="command-line-options.html#intensity">-intensity</a> methods to
4157convert the given image into a linear-grayscale image. </p>
4158
4159<p>For example, to convert an image to (linear) Rec709Luminance grayscale, type:</p>
4160
4161<pre>
4162convert in.png -grayscale Rec709Luminance out.png
4163</pre>
4164
4165<p>which is equivalent to:</p>
4166
4167<pre>
4168convert in.png -colorspace gray out.png
4169</pre>
4170
4171<p>Similarly, to convert an image to (non-linear) Rec709Luma grayscale, type:</p>
4172
4173<pre>
4174convert in.png -grayscale Rec709Luma out.png
4175</pre>
4176
4177<p>which is equivalent to:</p>
4178
4179<pre>
4180convert in.png -set colorspace RGB -colorspace gray out.png
4181</pre>
4182
4183<p>Note that a 'colorspace' intensity method will produce the same result
4184regardless of the current colorpsace of the image. But a 'mathematical'
4185intensity method will depend on the current colorspace the image is currently
4186using. </p>
4187
4188<p>While this operation uses an <a href="command-line-options.html#intensity">-intensity</a> method,
4189it does not use or set the <a href="command-line-options.html#intensity">-intensity</a> setting, so
4190will not effect other operations that may use that setting.</p>
4191
4192
4193<div style="margin: auto;">
4194 <h4><a id="green-primary"></a>-green-primary <var>x,y</var></h4>
4195</div>
4196
4197<p class="magick-description">green chromaticity primary point.</p>
4198
4199
4200<div style="margin: auto;">
4201 <h4><a id="hald-clut"></a>-hald-clut</h4>
4202</div>
4203
4204<p class="magick-description">apply a Hald color lookup table to the image.</p>
4205
4206<p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4207dimensions. Create it with the <code>HALD:</code> prefix (e.g. HALD:8). You
4208can apply any color transformation to the Hald image and then use this option
4209to apply the transform to the image. </p>
4210
4211<pre>
4212convert image.png hald.png -hald-clut transform.png
4213</pre>
4214
4215<p>This option provides a convenient method for you to use Gimp or Photoshop
4216to make color corrections to the Hald CLUT image and subsequently apply them
4217to multiple images using an ImageMagick script. </p>
4218
4219<p>Note that the representation is only of the normal RGB color space and that
4220the whole color value triplet is used for the interpolated lookup of the
4221represented 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
4222images transparency or alpha/matte channel.</p>
4223
4224<p>See also <a href="command-line-options.html#clut">-clut</a> which provides color value replacement
4225of the individual color channels, usually involving a simpler gray-scale
4226image. E.g: gray-scale to color replacement, or modification by a histogram
4227mapping. </p>
4228
4229
4230<div style="margin: auto;">
4231 <h4><a id="help"></a>-help</h4>
4232</div>
4233
4234<p class="magick-description">print usage instructions.</p>
4235
4236<div style="margin: auto;">
4237 <h4><a id="highlight-color"></a>-highlight-color <var>color</var></h4>
4238</div>
4239
4240<p class="magick-description">when comparing images, emphasize pixel differences with this color.</p>
4241
4242<div style="margin: auto;">
4243 <h4><a id="hough-lines"></a>-hough-lines <var>width</var>x<var>height</var>{<var>+threshold</var>}</h4>
4244</div>
4245
4246<p class="magick-description">identify straight lines in the image (e.g. -hough-lines 9x9+195).</p>
4247
4248<p>Use the Hough line detector with any binary edge extracted image to locate and draw any straight lines that it finds.</p>
4249
4250<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>.
4251
4252<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>
4253
4254<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>
4255
4256<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>
4257
4258<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>
4259
4260<p>A text file listing the endpoints and counts may be created by using the suffix, .mvg, for the output image.</p>
4261
4262<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>
4263
4264<div style="margin: auto;">
4265 <h4><a id="iconGeometry"></a>-iconGeometry <var>geometry</var></h4>
4266</div>
4267
4268<p class="magick-description">specify the icon geometry.</p>
4269
4270<p>Offsets, if present in the geometry specification, are handled in the same
4271manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4272handle negative offsets.</p>
4273
4274<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4275
4276<div style="margin: auto;">
4277 <h4><a id="iconic"></a>-iconic</h4>
4278</div>
4279
4280<p class="magick-description">start in icon mode in X Windows", 'animate', 'display</p>
4281
4282<div style="margin: auto;">
4283 <h4><a id="identify"></a>-identify</h4>
4284</div>
4285
4286<p class="magick-description">identify the format and characteristics of the image.</p>
4287
4288<p>This information is printed: image scene number; image name; image size;
4289the image class (<var>DirectClass</var> or <var>PseudoClass</var>); the total number of unique colors; and the
4290number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4291a description of the image class.</p>
4292
4293<p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4294in the image and color reduction error values are printed. Refer to <a href="quantize.html">color
4295reduction algorithm</a> for a description of these values.</p>
4296
4297<p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4298amounts of image properties are displayed including image statistics, profiles,
4299image histogram, and others.</p>
4300
4301<div style="margin: auto;">
4302 <h4><a id="ift"></a>-ift</h4>
4303</div>
4304
4305<p class="magick-description">implements the inverse discrete Fourier transform (DFT).</p>
4306
4307<p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4308users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4309images from the frequency domain to a single image in the normal or spatial
4310domain. See for example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4311<a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4312<a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4313
4314<p>For example, depending upon the image format used to store the result of
4315the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4316
4317<pre>
4318convert fft_image.miff -ift fft_image_ift.png
4319</pre>
4320
4321<p>or</p>
4322
4323<pre>
4324convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png
4325</pre>
4326
4327<p>The resulting image may need to be cropped due to padding introduced when
4328the 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
4329the right and/or bottom sides of the image.</p>
4330
4331<p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4332use <a href="command-line-options.html#ift">-ift</a>.</p>
4333
4334<p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4335and imaginary images from the frequency domain to a single image in the normal
4336(spatial) domain.</p>
4337
4338<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 explictly normalize the IFT and unnormalize the FFT.</p>
4339
4340<div style="margin: auto;">
4341 <h4><a id="immutable"></a>-immutable</h4>
4342</div>
4343
4344<p class="magick-description">make image immutable.</p>
4345
4346<div style="margin: auto;">
4347 <h4><a id="implode"></a>-implode <var>factor</var></h4>
4348</div>
4349
4350<p class="magick-description">implode image pixels about the center.</p>
4351
4352<div style="margin: auto;">
4353 <h4><a id="insert"></a>-insert <var>index</var></h4>
4354</div>
4355
4356<p class="magick-description">insert the last image into the image sequence.</p>
4357
4358<p>This option takes last image in the current image sequence and inserts it
4359at the given index. If a negative index is used, the insert position is
4360calculated before the last image is removed from the sequence. As such
4361<code>-insert -1</code> will result in no change to the image sequence.</p>
4362
4363<p>The <code>+insert</code> option is equivalent to <code>-insert -1</code>. In
4364other words, insert the last image, at the end of the current image sequence.
4365Consequently this has no effect on the image sequence order.</p>
4366
4367<div style="margin: auto;">
4368 <h4><a id="intensity"></a>-intensity <var>method</var></h4>
4369</div>
4370
4371<p class="magick-description">method to generate intensity value from pixel.</p>
4372
4373<p>ImageMagick provides a number of methods used in situations where an
4374operatory needs to determine a single grayscale value for some purpose, from
4375an image with red, green, and blue pixel components. Typically the linear
4376<code>Rec709Luminance</code> formula is used, which is the same formula used when
4377converting images to <code>-colorspace gray</code>. </p>
4378
4379<p>The following formulas are currently provided, and will first convert
4380the pixel values to linear-RGB or non-linear sRGB colorspace before
4381being applied to calulate the final greyscale value. </p>
4382
4383<pre>
4384 Rec601Luma 0.298839R' + 0.586811G'+ 0.114350B'
4385 Rec601Luminance 0.298839R + 0.586811G + 0.114350B
4386 Rec709Luma 0.212656R' + 0.715158G' + 0.072186B'
4387 Rec709Luminance 0.212656R + 0.715158G + 0.072186B
4388 Brightness max(R', G', B')
4389 Lightness (min(R', G', B') + max(R', G', B')) / 2.0
4390</pre>
4391<p>Note that the above R,G,B values is the image's linear-RGB values, while
4392R',G',B' are sRGB non-linear values. </p>
4393
4394<p>These intensity methods are mathematical in nature and will use the
4395current value in the images respective R,G,B channel regardless of
4396what that is, or what colorspace the image is currently using.</p>
4397
4398<pre>
4399 Average (R + G + B) / 3.0
4400 MS (R^2 + G^2 + B^2) / 3.0
4401 RMS sqrt( (R^2 + G^2 + B^2) / 3.0 )
4402</pre>
4403
4404<p>These methods are often used for other purposes, such as generating a
4405grayscale difference image between two color images (using <a href="command-line-options.html#compose">-compose</a> '<code>Difference</code>' composition. </p>
4406
4407<p> For example The 'MS' (Mean Squared) setting is good for minimizing color
4408error comparisions. While... The method 'RMS' (Root Mean Squared) for
4409example is appropriate for calculating color vector distance, from a color
4410difference 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>
4411
4412<p>See also <a href="command-line-options.html#grayscale">-grayscale</a> which applies one of the above
4413grayscaling formula directly to an image without setting the <a href="command-line-options.html#intensity">-intensity</a> setting.</p>
4414
4415<p>The <a href="command-line-options.html#colorspace">-colorspace gray</a> image conversion also uses
4416the current intensity setting, but will always convert the image to the
4417appropriate sRGB or linear-RGB colorspace before appling the above
4418function.</p>
4419
4420<p>To print a complete list of posible pixel intensity setting methods, use <a href="command-line-options.html#list">-list intensity</a>.</p>
4421
4422<p>Operators affected by the <a href="command-line-options.html#intensity">-intensity</a> setting include:</p>
4423
4424<pre>
4425-adaptive-blur
4426-adaptive-sharpen
4427-black-threshold
4428-clut (when mapping greyscale CLUT image to alpha channel if set by -channels)
4429-colors for gray colorspace
4430-compose {LightenIntensity, DarkenIntensity, CopyOpacity, CopyBlack}
4431-contrast-stretch
4432-distort {ErodeIntensity, DilateIntensity}
4433-normalize
4434-random-threshold
4435-selective-blur
4436-shade
4437-threshold
4438-tint
4439-white-threshold
4440</pre>
4441
4442<div style="margin: auto;">
4443 <h4><a id="intent"></a>-intent <var>type</var></h4>
4444</div>
4445
4446<p class="magick-description">use this type of rendering intent when managing the image color.</p>
4447
4448<p>Use this option to affect the color management operation of an image (see
4449<a href="command-line-options.html#profile">-profile</a>). Choose from these intents: <code>Absolute,
4450Perceptual, Relative, Saturation</code>.</p>
4451
4452<p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4453
4454<p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4455
4456<div style="margin: auto;">
4457 <h4><a id="interlace"></a>-interlace <var>type</var></h4>
4458</div>
4459
4460<p class="magick-description">the type of interlacing scheme.</p>
4461
4462<p>Choose from:</p>
4463
4464<pre>
4465 none
4466 line
4467 plane
4468 partition
4469 JPEG
4470 GIF
4471 PNG
4472</pre>
4473
4474<p>This option is used to specify the type of interlacing scheme for raw image
4475formats such as <code>RGB</code> or <code>YUV</code>.</p>
4476
4477<p><code>None</code> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4478
4479<p><code>Line</code> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4480
4481<p><code>Plane</code> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4482
4483<p><code>Partition</code> is like plane except the different planes are saved to
4484individual files (e.g. image.R, image.G, and image.B).</p>
4485
4486<p>Use <code>Line</code> or <code>Plane</code> to create an <code>interlaced
4487PNG</code> or <code>GIF</code> or <code>progressive JPEG</code> image.</p>
4488
4489<p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4490interlace</a>.</p>
4491
4492<div style="margin: auto;">
4493 <h4><a id="interpolate"></a>-interpolate <var>type</var></h4>
4494</div>
4495
4496<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>
4497
4498<p>When looking up the color of a pixel using a non-integer floating point
4499value, you typically fall in between the pixel colors defined by the source
4500image. This setting determines how the color is determined from the colors of
4501the pixels surrounding that point. That is how to determine the color of a
4502point that falls between two, or even four different colored pixels. </p>
4503
4504<pre>
4505 integer The color of the top-left pixel (floor function)
4506 nearest-neighbor The nearest pixel to the lookup point (rounded function)
4507 average The average color of the surrounding four pixels
4508 bilinear A double linear interpolation of pixels (the default)
4509 mesh Divide area into two flat triangular interpolations
4510 bicubic Fitted bicubic-spines of surrounding 16 pixels
4511 spline Direct spline curves (colors are blurred)
4512 filter Use resize <a href="command-line-options.html#filter">-filter</a> settings
4513</pre>
4514
4515<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>
4516
4517<p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4518
4519<p>See also <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a>, for control of the
4520lookup for positions outside the boundaries of the image. </p>
4521
4522
4523<div style="margin: auto;">
4524 <h4><a id="interline-spacing"></a>-interline-spacing <var>value</var></h4>
4525</div>
4526
4527<p class="magick-description">the space between two text lines.</p>
4528
4529<div style="margin: auto;">
4530 <h4><a id="interword-spacing"></a>-interword-spacing <var>value</var></h4>
4531</div>
4532
4533<p class="magick-description">the space between two words.</p>
4534
4535<div style="margin: auto;">
4536 <h4><a id="kerning"></a>-kerning <var>value</var></h4>
4537</div>
4538
4539<p class="magick-description">the space between two letters.</p>
4540
4541<div style="margin: auto;">
4542 <h4><a id="kuwahara"></a>-kuwahara <var>radius</var><br>-kuwahara <var>radius</var>x<var>sigma</var></h4>
4543</div>
4544
4545<p class="magick-description">edge preserving noise reduction filter.</p>
4546
4547<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>
4548
4549
4550<div style="margin: auto;">
4551 <h4><a id="label"></a>-label <var>name</var></h4>
4552</div>
4553
4554<p class="magick-description">assign a label to an image.</p>
4555
4556<p>Use this option to assign a specific label to the image, as it is read in
4557or created. You can use the <a href="command-line-options.html#set">-set</a> operation to re-assign
4558a the labels of images already read in. Image formats such as TIFF, PNG,
4559MIFF, supports saving the label information with the image.</p>
4560
4561<p>When saving an image to a <var>PostScript</var> file, any label
4562assigned to an image is used as a header string to print above the postscript
4563image. </p>
4564
4565<p>You can include the image filename, type, width, height, or other image
4566attribute by embedding special format character. See <a href="escape.html">Format and Print Image
4567Properties</a> for details of the percent escape codes.</p>
4568
4569<p>For example,</p>
4570
4571<p class="crtsnip">
4572 -label "%m:%f %wx%h" bird.miff
4573</p>
4574
4575<p>assigns an image label of <code>MIFF:bird.miff 512x480</code> to the
4576"<code>bird.miff</code>" image and whose width is 512 and height is 480, as it
4577is read in. If a <a href="command-line-options.html#label">+label</a> option was used instead, any
4578existing label present in the image would be used. You can remove all labels
4579from an image by assigning the empty string. </p>
4580
4581<p>A label is not drawn on the image, but is embedded in the image datastream
4582via <var>Label</var> tag or similar mechanism. If you want the label to be
4583visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
4584during the final processing in the creation of an image montage.</p>
4585
4586<p>If the first character of <var>string</var> is <var>@</var>, the image label is read from a file titled by the
4587remaining characters in the string. Labels in a file are literal, no embedded
4588formatting characters are recognized.</p>
4589
4590
4591<div style="margin: auto;">
4592 <h4><a id="lat"></a>-lat <var>width</var><br>-lat <var>width</var>x<var>height</var>{<var>+-</var>}<var>offset</var>{<var>%</var>}</h4>
4593</div>
4594
4595<p class="magick-description">perform local adaptive threshold.</p>
4596
4597<p>Adaptively threshold each pixel based on the value of pixels in a
4598surrounding window. If the current pixel is lighter than this average plus
4599the optional <code>offset</code>, then it is made white, otherwise it is made
4600black. Small variations in pixel values such as found in scanned documents
4601can be ignored if offset is positive. A negative offset will make it more
4602sensitive to those small variations. </p>
4603
4604<p>This is commonly used to threshold images with an uneven background. It is
4605based on the assumption that average color of the small window is the
4606the local background color, from which to separate the foreground color. </p>
4607
4608
4609<div style="margin: auto;">
4610 <h4><a id="layers"></a>-layers <var>method</var></h4>
4611</div>
4612
4613<p class="magick-description">handle multiple images forming a set of image layers or animation frames.</p>
4614
4615<p>Perform various image operation methods to a ordered sequence of images
4616which may represent either a set of overlaid 'image layers', a GIF disposal
4617animation, or a fully-'coalesced' animation sequence. </p>
4618
4619<table class="table table-condensed table-striped">
4620 <tbody>
4621 <tr>
4622 <th style="width: 8%">Method</th>
4623 <th>Description</th>
4624 </tr>
4625
4626 <tr>
4627 <td>compare-any</td>
4628 <td>Crop the second and later frames to the smallest rectangle
4629 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>
4630 </tr>
4631
4632 <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
4633 working, especially when animation used layer disposal methods such as
4634 '<code>Previous</code>' or '<code>Background</code>'. </td>
4635 </tr>
4636
4637 <tr>
4638 <td>compare-clear</td>
4639 <td>As '<code>compare-any</code>' but crop to the bounds of any
4640 opaque pixels which become transparent in the second frame. That is the
4641 smallest image needed to mask or erase pixels for the next frame. </td>
4642 </tr>
4643
4644 <tr>
4645 <td>compare-overlay</td>
4646 <td>As '<code>compare-any</code>' but crop to pixels that add
4647 extra color to the next image, as a result of overlaying color pixels.
4648 That is the smallest single overlaid image to add or change colors. </td>
4649 </tr>
4650
4651 <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose">-compose</a> alpha
4652 composition method '<code>change-mask</code>', to reduce the image to
4653 just the pixels that need to be overlaid. </td>
4654 </tr>
4655
4656 <tr>
4657 <td>coalesce</td>
4658 <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
4659 current image sequence to form a fully defined animation sequence, as
4660 it should be displayed. Effectively converting a GIF animation into a
4661 'film strip'-like animation. </td>
4662 </tr>
4663
4664 <tr>
4665 <td>composite</td>
4666 <td>Alpha Composition of two image lists, separated by a
4667 "<code>null:</code>" image, with the destination image list first, and
4668 the source images last. An image from each list are composited
4669 together until one list is finished. The separator image and source
4670 image lists are removed. </td>
4671 </tr>
4672
4673
4674 <tr><td></td>
4675 <td>The <a href="command-line-options.html#geometry">-geometry</a> offset is adjusted according
4676 to <a href="command-line-options.html#gravity">-gravity</a> in accordance of the virtual
4677 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
4678 added to the final composite positioning of each image. </td> </tr>
4679
4680 <tr><td></td>
4681 <td>If one of the image lists only contains one image, that image is
4682 applied to all the images in the other image list, regardless of which
4683 list it is. In this case it is the image meta-data of the list which
4684 preserved. </td>
4685 </tr>
4686
4687
4688 <tr>
4689 <td>dispose</td>
4690 <td>This like '<code>coalesce</code>' but shows the look of
4691 the animation after the layer disposal method has been applied, before
4692 the next sub-frame image is overlaid. That is the 'dispose' image that
4693 results from the application of the GIF <a href="command-line-options.html#dispose">-dispose</a> method. This allows you to check what
4694 is going wrong with a particular animation you may be developing.
4695 </td>
4696 </tr>
4697
4698 <tr>
4699 <td>flatten</td>
4700 <td>Create a canvas the size of the first images virtual
4701 canvas using the current <a href="command-line-options.html#background">-background</a> color,
4702 and <a href="command-line-options.html#compose">-compose</a> each image in turn onto that
4703 canvas. Images falling outside that canvas is clipped. Final
4704 image will have a zero virtual canvas offset. </td>
4705 </tr>
4706
4707 <tr><td></td>
4708 <td>This usually used as one of the final 'image layering' operations
4709 overlaying all the prepared image layers into a final image. </td>
4710 </tr>
4711
4712 <tr><td></td>
4713 <td>For a single image this method can also be used to fillout a virtual
4714 canvas with real pixels, or to underlay an opaque color to remove
4715 transparency from an image.</td>
4716 </tr>
4717
4718
4719 <tr>
4720 <td>merge</td>
4721 <td>As 'flatten' method but merging all the given image
4722 layers to create a new layer image just large enough to hold all the
4723 image without clipping or extra space. The new images virtual offset
4724 will preserve the position of the new layer, even if this offset is
4725 negative. The virtual canvas size of the first image is preserved.
4726 </td>
4727 </tr>
4728
4729 <tr><td></td><td>Caution is advised when handling image layers with
4730 negative offsets as few image file formats handle them correctly.
4731 Following this operation method with <a href="command-line-options.html#repage">+repage</a>
4732 will remove the layer offset, and create an image in which all the
4733 overlaid image positions relative to each other is preserved, though
4734 not necessarily exactly where you specified them.
4735 </td>
4736 </tr>
4737
4738 <tr><td></td><td>See also 'trim-bounds' below which is closely related but
4739 without doing the'flatten' to merge the images together. </td>
4740 </tr>
4741
4742 <tr>
4743 <td>mosaic</td>
4744 <td>As 'flatten' method but expanding the initial canvas size
4745 of the first image in a positive direction only so as to hold all the
4746 image layers. However as a virtual canvas is 'locked' to the origin,
4747 by its own definition, image layers with a negative offsets will still
4748 become clipped by the top and left edges. See 'merge' or 'trim-bounds'
4749 if this could be a problem. </td>
4750
4751 </tr>
4752
4753 <tr><td></td><td>This method is commonly used to layout individual image
4754 using various offset but without knowing the final canvas size. The
4755 resulting image will, like 'flatten' not have any virtual offset, so
4756 can be saved to any image file format. </td>
4757 </tr>
4758
4759
4760 <tr>
4761 <td>optimize</td>
4762 <td>Optimize a coalesced animation, into GIF animation using
4763 a number of general techniques. This currently a short cut to
4764 apply both the '<code>optimize-frame</code>', and
4765 '<code>optimize-transparency</code>' methods but may be expanded to
4766 include other optimization methods as they are developed. </td>
4767 </tr>
4768
4769 <tr>
4770 <td>optimize-frame</td>
4771 <td>Optimize a coalesced animation, into GIF animation by
4772 reducing the number of pixels per frame as much as possible by
4773 attempting to pick the best layer disposal method to use, while ensuring
4774 the result will continue to animate properly. </td>
4775 </tr>
4776
4777 <tr><td></td><td> There is no guarantee that the best optimization is found.
4778 But then no reasonably fast GIF optimization algorithm can do this.
4779 However this does seem to do better than most other GIF frame
4780 optimizers seen. </td>
4781 </tr>
4782
4783 <tr>
4784 <td>optimize-plus</td>
4785 <td>As '<code>optimize-frame</code>' but attempt to improve the
4786 overall optimization by adding extra frames to the animation, without
4787 changing the final look or timing of the animation. The frames are
4788 added to attempt to separate the clearing of pixels from the
4789 overlaying of new additional pixels from one animation frame to the
4790 next. If this does not improve the optimization (for the next frame
4791 only), it will fall back to the results of the previous normal
4792 '<code>optimize-frame</code>' technique. </td>
4793 </tr>
4794
4795 <tr><td></td><td>There is the possibility that the change in the disposal
4796 style will result in a worsening in the optimization of later frames,
4797 though this is unlikely. In other words there no guarantee that it is
4798 better than the normal '<code>optimize-frame</code>' technique. For some
4799 animations however you can get a vast improvement in the final
4800 animation size. </td>
4801 </tr>
4802
4803 <tr>
4804 <td>optimize-transparency</td>
4805 <td>Given a GIF animation, replace any pixel in the sub-frame
4806 overlay images with transparency, if it does not change the resulting
4807 animation by more than the current <a href="command-line-options.html#fuzz">-fuzz</a> factor.
4808 </td>
4809 </tr>
4810
4811 <tr><td></td><td>This should allow a existing frame optimized GIF animation
4812 to compress into a smaller file size due to larger areas of one
4813 (transparent) color rather than a pattern of multiple colors repeating
4814 the current disposed image of the last frame. </td>
4815 </tr>
4816
4817 <tr>
4818 <td>remove-dups</td>
4819 <td>Remove (and merge time delays) of duplicate consecutive
4820 images, so as to simplify layer overlays of coalesced animations.
4821 </td>
4822 </tr>
4823
4824 <tr><td></td><td>Usually this a result of using a constant time delay
4825 across the whole animation, or after a larger animation was split into
4826 smaller sub-animations. The duplicate frames could also have been
4827 used as part of some frame optimization methods. </td>
4828 </tr>
4829
4830 <tr>
4831 <td>remove-zero</td>
4832 <td>Remove any image with a zero time delay, unless ALL the
4833 images have a zero time delay (and is not a proper timed animation, a
4834 warning is then issued). </td>
4835 </tr>
4836
4837 <tr><td></td><td>In a GIF animation, such images are usually frames which
4838 provide partial intermediary updates between the frames that are
4839 actually displayed to users. These frames are usually added for
4840 improved frame optimization in GIF animations. </td>
4841 </tr>
4842
4843 <tr>
4844 <td>trim-bounds</td>
4845 <td>Find the bounds of all the images in the current
4846 image sequence, then adjust the offsets so all images are contained on
4847 a minimal positive canvas. None of the image data is modified or
4848 merged, only the individual image virtual canvas size and offset.
4849 All the images is given the same canvas size, and and will have
4850 a positive offset, but will remain in the same position relative to
4851 each other. As a result of the minimal canvas size at least one image
4852 will touch every edge of that canvas. The image data touching those
4853 edges however may be transparent. </td>
4854 </tr>
4855
4856 <tr><td></td><td>The result is much like if you used 'merge' followed by a
4857 <a href="command-line-options.html#repage">+repage</a> option, except that all the images
4858 have been kept separate. If 'flatten' is used after using
4859 'trim-bounds' you will get the same result. </td>
4860 </tr>
4861
4862 </tbody>
4863</table>
4864
4865<p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
4866
4867<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
4868the 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
4869GIF <a href="command-line-options.html#dispose">-dispose</a> and <a href="command-line-options.html#delay">-delay</a>
4870settings. </p>
4871
4872
4873<div style="margin: auto;">
4874 <h4><a id="level"></a>-level <var>black_point</var>{,<var>white_point</var>}{<var>%</var>}{,<var>gamma</var>}</h4>
4875</div>
4876
4877<p class="magick-description">adjust the level of image channels.</p>
4878
4879<p>Given one, two or three values delimited with commas: black-point,
4880white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
4881white points range from 0 to <var>QuantumRange</var>, or from 0 to
4882100%; if the white point is omitted it is set to (<var>QuantumRange</var> - black_point), so as to center contrast changes.
4883If a <code>%</code> sign is present anywhere in the string, both black and white
4884points 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
4885default of 1.0 (no gamma correction) is assumed.</p>
4886
4887<p>In normal usage (<code>-level</code>) the image values are stretched so that
4888the given '<code>black_point</code>' value in the original image is set to zero
4889(or black), while the given '<code>white_point</code>' value is set to <var>QuantumRange</var> (or white). This provides you with direct
4890contrast adjustments to the image. The '<code>gamma</code>' of the resulting
4891image will then be adjusted. </p>
4892
4893<p>From ImageMagick v6.4.1-9 using the plus form of the operator
4894(<code>+level</code>) or adding the special '!' flag anywhere in the argument
4895list, will cause the operator to do the reverse of the level adjustment. That
4896is a zero, or <var>QuantumRange</var> value (black, and white, resp.)
4897in the original image, is adjusted to the given level values, allowing you to
4898de-contrast, or compress the channel values within the image. The
4899'<code>gamma</code>' is adjusted before the level adjustment to de-contrast the
4900image is made. </p>
4901
4902<p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
4903setting are adjusted (defaults to RGB color channels only), allowing you to
4904limit the effect of this operator. </p>
4905
4906<p>Please note that the transparency channel is treated as 'matte'
4907values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
4908
4909
4910<div style="margin: auto;">
4911 <h4><a id="level-colors"></a>-level-colors {<var>black_color</var>}{,}{<var>white_color</var>}</h4>
4912</div>
4913
4914<p class="magick-description">adjust the level of an image using the provided dash separated colors.</p>
4915
4916<p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
4917value value for each color channel is determined by the
4918'<code>black_color</code>' and '<code>white_color</code>' colors given (as
4919described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
4920
4921<p>This effectually means the colors provided to <code>-level-colors</code>
4922is mapped to become 'black' and 'white' respectively, with all the other
4923colors linearly adjusted (or clipped) to match that change. Each channel is
4924adjusted separately using the channel values of the colors specified. </p>
4925
4926<p>On the other hand the plus form of the operator (<code>+level-colors</code>)
4927will map the image color 'black' and 'white' to the given colors
4928respectively, resulting in a gradient (de-contrasting) tint of the image to
4929those colors. This can also be used to convert a plain gray-scale image into a
4930one using the gradient of colors specified. </p>
4931
4932<p>By supplying a single color with a comma separator either before or after
4933that color, will just replace the respective 'black' or 'white' point
4934respectively. But if no comma separator is provided, the given color is
4935used for both the black and white color points, making the operator either
4936threshold the images around that color (- form) or set all colors to that
4937color (+ form). </p>
4938
4939
4940<div style="margin: auto;">
4941 <h4><a id="limit"></a>-limit <var>type value</var></h4>
4942</div>
4943
4944<p class="magick-description">Set the pixel cache resource limit.</p>
4945
4946<p>Choose from: <code>area</code>, <code>disk</code>, <code>file</code>,
4947<code>map</code>, <code>memory</code>, <code>thread</code>, or <code>time</code>.</p>
4948
4949<p>The value for <code>file</code> is in number of files. The other limits are
4950in bytes. Define arguments for the memory, map, area, and disk resource limits
4951with SI prefixes (.e.g 100MB).</p>
4952
4953<p>By default the limits are 768 files, 3GB of image area, 1.5GiB memory, 3GiB
4954memory map, and 18.45EB of disk. These limits are adjusted relative to the
4955available resources on your computer if this information is available. When
4956any limit is reached, ImageMagick fails in some fashion but attempts to take
4957compensating actions, if possible. For example, the following limits
4958memory:</p>
4959
4960<p class="crtsnip">
4961 -limit memory 32MiB -limit map 64MiB
4962</p>
4963
4964<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>
4965
4966<pre>
4967-&gt; identify -list resource
4968Resource limits:
4969 Width: 100MP
4970 Height: 100MP
4971 Area: 25.181GB
4972 Memory: 11.726GiB
4973 Map: 23.452GiB
4974 Disk: unlimited
4975 File: 768
4976 Thread: 12
4977 Throttle: 0
4978 Time: unlimited
4979</pre>
4980
4981<p>Requests for pixel storage to keep intermediate images are satisfied by one
4982of three resource categories: in-memory pool, memory-mapped files pool, and
4983disk pool (in that order) depending on the <a href="command-line-options.html#limit">‑limit</a> settings
4984and whether the system honors a resource request. If the total size of
4985allocated pixel storage in the given pool reaches the corresponding limit, the
4986request is passed to the next pool. Additionally, requests that exceed the
4987<code>area</code> limit automagically are allocated on disk.</p>
4988
4989<p>To illustrate how ImageMagick utilizes resource limits, consider a typical
4990image resource request. First, ImageMagick tries to allocate the pixels in
4991memory. The request might be denied if the resource request exceeds the
4992<code>memory</code> limit or if the system does not honor the request. If
4993a memory request is not honored, the pixels are allocated to disk and the file
4994is memory-mapped. However, if the allocation request exceeds the
4995<code>map</code> limit, the resource allocation goes to disk. In all cases, if
4996the resource request exceeds the <code>area</code> limit, the pixels are
4997automagically cached to disk. If the disk has a hard limit, the program
4998fails.</p>
4999
5000<p>In most cases you simply do not need to concern yourself with resource
5001limits. ImageMagick chooses reasonable defaults and most images do not tax
5002your computer resources. Where limits do come in handy is when you process
5003images that are large or on shared systems where ImageMagick can consume all
5004or most of the available memory. In this case, the ImageMagick workflow slows
5005other processes or, in extreme cases, brings the system to a halt. Under
5006these circumstances, setting limits give some assurances that the ImageMagick
5007workflow will not interfere with other concurrent uses of the computer. For
5008example, assume you have a web interface that processes images uploaded from
5009the Internet. To assure ImageMagick does not exceed 10MiB of memory you can
5010simply set the area limit to 10MiB:</p>
5011
5012<p class="crtsnip">
5013-limit area 10MB
5014</p>
5015
5016<p>Now whenever a large image is processed, the pixels are automagically
5017cached to disk instead of memory. This of course implies that large images
5018typically process very slowly, simply because pixel processing in memory can
5019be an order of magnitude faster than on disk. Because your web site users
5020might inadvertently upload a huge image to process, you should set a disk
5021limit as well:</p>
5022
5023<p class="crtsnip">
5024-limit area 10MB -limit disk 500MB
5025</p>
5026
5027<p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
5028
5029<p>In addition to command-line resource limit option, resources can be set
5030with <a href="resources.html#environment">environment variables</a>. Set the
5031environment variables <code>MAGICK_AREA_LIMIT</code>,
5032<code>MAGICK_DISK_LIMIT</code>, <code>MAGICK_FILE_LIMIT</code>,
5033<code>MAGICK_MEMORY_LIMIT</code>, <code>MAGICK_MAP_LIMIT</code>,
5034<code>MAGICK_THREAD_LIMIT</code>, <code>MAGICK_TIME_LIMIT</code> for limits of
5035image area, disk space, open files, heap memory, memory map, number of threads
5036of execution, and maximum elapsed time in seconds respectively.</p>
5037
5038<p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
5039their commands and then scouring the generated output for references to the
5040pixel cache, in order to determine how the pixel cache was allocated and how
5041resources were consumed. Advanced Unix/Linux users can pipe that output
5042through <code>grep memory|open|destroy|disk</code> for more readable sifting.
5043</p>
5044
5045<p>For more about ImageMagick's use of resources, see the section <b>Cache
5046Storage and Resource Requirements</b> on the <a href="architecture.html#cache%20">Architecture</a> page. </p>
5047
5048<div style="margin: auto;">
5049 <h4><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>}}</h4>
5050</div>
5051
5052<p class="magick-description">Linear with saturation stretch.</p>
5053
5054<p>This is very similar to <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
5055and uses a 'histogram bin' to determine the range of color values that needs to
5056be stretched. However it then stretches those colors using the <a href="command-line-options.html#level">-level</a> operator.</p>
5057
5058<p>As such while the initial determination may have 'binning' round off
5059effects, the image colors are stretched mathematically, rather than using the
5060histogram bins. This makes the operator more accurate. </p>
5061
5062<p>note however that a <a href="command-line-options.html#linear-stretch">-linear-stretch</a> of
5063'<code>0</code>' does nothing, while a value of '<code>1</code>' does a near
5064perfect stretch of the color range. </p>
5065
5066<p>See also <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect'
5067normalization of mathematical images. </p>
5068
5069<p>This operator is under review for re-development. </p>
5070
5071
5072<div style="margin: auto;">
5073 <h4><a id="linewidth"></a>-linewidth</h4>
5074</div>
5075
5076<p class="magick-description">the line width for subsequent draw operations.</p>
5077
5078<div style="margin: auto;">
5079 <h4><a id="liquid-rescale"></a>-liquid-rescale <var>geometry</var></h4>
5080</div>
5081
5082<p class="magick-description">rescale image with seam-carving.</p>
5083
5084<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5085
5086<div style="margin: auto;">
5087 <h4><a id="list"></a>-list <var>type</var></h4>
5088</div>
5089
5090<p class="magick-description">Print a list of supported arguments for various options or settings. Choose from these list types:</p>
5091
5092<pre>
5093 Align Alpha Boolean Channel
5094 Class ClipPath Coder Color
5095 Colorspace Command Compose Compress
5096 Configure DataType Debug Decoration
5097 Delegate Direction Dispose Distort
5098 Dither Endian Evaluate FillRule
5099 Filter Font Format Function
5100 Gravity ImageList Intent Interlace
5101 Interpolate Kernel Layers LineCap
5102 LineJoin List Locale LogEvent
5103 Log Magic Method Metric
5104 Mime Mode Morphology Module
5105 Noise Orientation Policy PolicyDomain
5106 PolicyRights Preview Primitive QuantumFormat
5107 Resource SparseColor Storage Stretch
5108 Style Threshold Type Units
5109 Validate VirtualPixel
5110</pre>
5111
5112<p>These lists vary depending on your version of ImageMagick. Use "<code>-list
5113list</code>" to get a complete listing of all the "<code>-list</code>" arguments
5114available:</p>
5115
5116<pre>
5117identify -list list
5118</pre>
5119
5120<div style="margin: auto;">
5121 <h4><a id="log"></a>-log <var>string</var></h4>
5122</div>
5123
5124<p class="magick-description">Specify format for debug log.</p>
5125
5126<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>
5127
5128<p>You can display the following components by embedding special format
5129characters:</p>
5130
5131<pre>
5132 %d domain
5133 %e event
5134 %f function
5135 %l line
5136 %m module
5137 %p process ID
5138 %r real CPU time
5139 %t wall clock time
5140 %u user CPU time
5141 %% percent sign
5142 \n newline
5143 \r carriage return
5144</pre>
5145
5146<p>For example:</p>
5147
5148<pre>
5149convert -debug coders -log "%u %m:%l %e" in.gif out.png
5150</pre>
5151
5152<p>The default behavior is to print all of the components.</p>
5153
5154<div style="margin: auto;">
5155 <h4><a id="loop"></a>-loop <var>iterations</var></h4>
5156</div>
5157
5158<p class="magick-description">add Netscape loop extension to your GIF animation.</p>
5159
5160<p>Set iterations to zero to repeat the animation an infinite number of times,
5161otherwise the animation repeats itself up to <var>iterations</var>
5162times.</p>
5163
5164<div style="margin: auto;">
5165 <h4><a id="lowlight-color"></a>-lowlight-color <var>color</var></h4>
5166</div>
5167
5168<p class="magick-description">when comparing images, de-emphasize pixel differences with this color.</p>
5169
5170<div style="margin: auto;">
5171 <h4><a id="magnify"></a>-magnify</h4>
5172</div>
5173
5174<p class="magick-description">double the size of the image with pixel art scaling.</p>
5175
5176
5177<div style="margin: auto;">
5178 <h4><a id="map"></a>-map <var>type</var></h4>
5179</div>
5180
5181<p class="magick-description">Display image using this <var>type</var>.</p>
5182
5183<p>Choose from these <var>Standard Colormap</var> types:</p>
5184
5185<pre>
5186 best
5187 default
5188 gray
5189 red
5190 green
5191 blue
5192</pre>
5193
5194<p>The <var>X server</var> must support the <var>Standard
5195Colormap</var> you choose, otherwise an error occurs. Use <code>list</code> as
5196the type and <code>display</code> searches the list of colormap types in
5197<code>top-to-bottom</code> order until one is located. See <var>xstdcmap(1)</var> for one way of creating Standard Colormaps.</p>
5198
5199
5200<div style="margin: auto;">
5201 <h4><a id="map_stream_"></a>-map <var>components</var></h4>
5202</div>
5203
5204<p class="magick-description">pixel map.</p>
5205
5206<p>Here are the valid components of a map:</p>
5207
5208<pre>
5209 r red pixel component
5210 g green pixel component
5211 b blue pixel component
5212 a alpha pixel component (0 is transparent)
5213 o opacity pixel component (0 is opaque)
5214 i grayscale intensity pixel component
5215 c cyan pixel component
5216 m magenta pixel component
5217 y yellow pixel component
5218 k black pixel component
5219 p pad component (always 0)
5220</pre>
5221
5222<p>You can specify as many of these components as needed in any order (e.g.
5223bgr). The components can repeat as well (e.g. rgbr).</p>
5224
5225
5226<div style="margin: auto;">
5227 <h4><a id="mask"></a>-mask
5228<var>filename</var></h4>
5229</div>
5230
5231<p class="magick-description">Prevent updates to image pixels specified by the mask.</p>
5232
5233<p>This the same as using a mask used for composite masking operations, with
5234grayscale values causing blended updates of the image the mask is attached to.
5235</p>
5236
5237<p>Use <a href="command-line-options.html#mask">+mask</a> to remove the mask from images.</p>
5238
5239<p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
5240but with strict boolean masking. </p>
5241
5242<div style="margin: auto;">
5243 <h4><a id="mattecolor"></a>-mattecolor <var>color</var></h4>
5244</div>
5245
5246<p class="magick-description">Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</p>
5247
5248<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5249
5250<p>The default matte color is <code>#BDBDBD</code>, <span style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5251
5252<div style="margin: auto;">
5253 <h4><a id="maximum"></a>-maximum</h4>
5254</div>
5255
5256<p class="magick-description">return the maximum intensity of an image sequence.</p>
5257
5258<p>Select the 'maximum' value from all the surrounding pixels. </p>
5259
5260<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5261name. </p>
5262
5263<div style="margin: auto;">
5264 <h4><a id="median"></a>-median <var>geometry</var></h4>
5265</div>
5266
5267<p class="magick-description">apply a median filter to the image.</p>
5268
5269<p>Select the 'middle' value from all the surrounding pixels. </p>
5270
5271<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5272name. </p>
5273
5274<div style="margin: auto;">
5275 <h4><a id="mean-shift"></a>-mean-shift <var>width</var>x<var>height</var>{<var>+distance</var>{%}}</h4>
5276</div>
5277
5278<p class="magick-description">image noise removal and color reduction/segmentation (e.g. -mean-shift 7x7+10%).</p>
5279
5280<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>
5281
5282<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 radius=sqrt((width-1)(height-1)/4) 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>
5283
5284<div style="margin: auto;">
5285 <h4><a id="metric"></a>-metric <var>type</var></h4>
5286</div>
5287
5288<p class="magick-description">Output to STDERR a measure of the differences between images according to the <var>type</var> given metric.</p>
5289
5290<p>Choose from:</p>
5291
5292<pre>
5293 AE absolute error count, number of different pixels (-fuzz effected)
5294 FUZZ mean color distance
5295 MAE mean absolute error (normalized), average channel error distance
5296 MEPP mean error per pixel (normalized mean error, normalized peak error)
5297 MSE mean error squared, average of the channel error squared
5298 NCC normalized cross correlation
5299 PAE peak absolute (normalized peak absolute)
5300 PHASH perceptual hash
5301 PSNR peak signal to noise ratio
5302 RMSE root mean squared (normalized root mean squared)
5303</pre>
5304
5305<p>Control the '<code>AE</code>', or absolute count of pixels that are different,
5306with the <a href="command-line-options.html#fuzz">-fuzz</a> factor (ignore pixels which
5307only changed by a small amount). Use '<code>PAE</code>' to find the
5308size of the <a href="command-line-options.html#fuzz">-fuzz</a> factor needed to make all pixels
5309'similar', while '<code>MAE</code>' determines the factor needed
5310for about half the pixels to be similar. </p>
5311
5312<p>The '<code>MEPP</code>' metric returns three different metrics
5313('<code>MAE</code>', '<code>MAE</code>' normalized, and '<code>PAE</code>'
5314normalized) from a single comparison run. </p>
5315
5316<p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5317metric</a> option.</p>
5318
5319
5320<div style="margin: auto;">
5321 <h4><a id="minimum"></a>-minimum</h4>
5322</div>
5323
5324<p class="magick-description">return the minimum intensity of an image sequence.</p>
5325
5326<p>Select the 'minimal' value from all the surrounding pixels. </p>
5327
5328<p>This is legacy option from the <a href="command-line-options.html#statistic">method</a> of the same
5329name. </p>
5330
5331
5332
5333<div style="margin: auto;">
5334 <h4><a id="mode"></a>-mode <var>geometry</var></h4>
5335</div>
5336
5337<p class="magick-description">make each pixel the \'predominant color\' of the neighborhood.'</p>
5338
5339<div style="margin: auto;">
5340 <h4>-mode <var>value</var></h4>
5341</div>
5342
5343<p class="magick-description">Mode of operation.</p>
5344
5345<p>Choose the <var>value</var> from these styles: <code>Frame,
5346Unframe, or Concatenate</code></p>
5347
5348<p>Use the <a href="command-line-options.html#list">-list</a> option with a '<code>Mode</code>' argument
5349for a list of <a href="command-line-options.html#mode">-mode</a> arguments available in your
5350ImageMagick installation.</p>
5351
5352
5353<div style="margin: auto;">
5354 <h4><a id="modulate"></a>-modulate <var>brightness</var>[,<var>saturation</var>,<var>hue</var>]</h4>
5355</div>
5356
5357<p class="magick-description">Vary the <var>brightness</var>, <var>saturation</var>, and <var>hue</var> of an image.</p>
5358
5359<p>The arguments are given as a percentages of variation. A value of 100 means
5360no change, and any missing values are taken to mean 100.</p>
5361
5362<p>The <var>brightness</var> is a multiplier of the overall
5363brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5364twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5365before and after. </p>
5366
5367<p>The <var>saturation</var> controls the amount of color in an
5368image. For example, 0 produce a grayscale image, while a large value such as
5369200 produce a very colorful, 'cartoonish' color.</p>
5370
5371<p>The <var>hue</var> argument causes a "rotation" of the colors
5372within the image by the amount specified. For example, 50 results in
5373a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5374A value of either 0 or 200 results in a complete 180 degree rotation of the
5375image. Using a value of 300 is a 360 degree rotation resulting in no change to
5376the original image. </p>
5377
5378<p>For example, to increase the color brightness by 20% and decrease the color
5379saturation by 10% and leave the hue unchanged, use <a href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5380
5381<p>Use <a href="command-line-options.html#set">-set</a> attribute of '<code>option:modulate:colorspace</code>' to specify which colorspace to
5382modulate. 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>
5383
5384<pre>
5385convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png
5386</pre>
5387
5388<div style="margin: auto;">
5389 <h4><a id="moments"></a>-moments</h4>
5390</div>
5391
5392<p class="magick-description">report image moments and perceptual hash.</p>
5393
5394
5395<div style="margin: auto;">
5396 <h4><a id="monitor"></a>-monitor</h4>
5397</div>
5398
5399<p class="magick-description">monitor progress.</p>
5400
5401
5402<div style="margin: auto;">
5403 <h4><a id="monochrome"></a>-monochrome</h4>
5404</div>
5405
5406<p class="magick-description">transform the image to black and white.</p>
5407
5408<div style="margin: auto;">
5409 <h4><a id="morph"></a>-morph <var>frames</var></h4>
5410</div>
5411
5412<p class="magick-description">morphs an image sequence.</p>
5413
5414<p>Both the image pixels and size are linearly interpolated to give the
5415appearance of a metamorphosis from one image to the next, over all the images
5416in 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>
5417argument determine how many images to interpolate between each image. </p>
5418
5419
5420<div style="margin: auto;">
5421 <h4><a id="morphology"></a>-morphology</h4>
5422 <h4>-morphology <var>method</var> <var>kernel</var></h4>
5423</div>
5424
5425<p class="magick-description">apply a morphology method to the image.</p>
5426
5427<p>Until I get around to writing an option summary for this, see <a href="http://www.imagemagick.org/Usage/morphology/">IM Usage Examples,
5428Morphology</a>. </p>
5429
5430
5431<div style="margin: auto;">
5432 <h4><a id="mosaic"></a>-mosaic</h4>
5433</div>
5434
5435<p class="magick-description">an simple alias for the <a href="command-line-options.html#layers">-layers</a> method "mosaic"</p>
5436
5437
5438<div style="margin: auto;">
5439 <h4><a id="motion-blur"></a>-motion-blur <var>radius</var><br>-motion-blur <var>radius</var>x<var>sigma</var>+<var>angle</var></h4>
5440</div>
5441
5442<p class="magick-description">simulate motion blur.</p>
5443
5444<p>Blur with the given radius, standard deviation (sigma), and angle. The
5445angle given is the angle toward which the image is blurred. That is the
5446direction people would consider the object is coming from. </p>
5447
5448<p>Note that the blur is not uniform distribution, giving the motion a
5449definite sense of direction of movement. </p>
5450
5451<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5452pixels which are outside the image proper are blurred into the final result.
5453</p>
5454
5455<div style="margin: auto;">
5456 <h4><a id="name"></a>-name</h4>
5457</div>
5458
5459<p class="magick-description">name an image.</p>
5460<div style="margin: auto;">
5461 <h4><a id="negate"></a>-negate</h4>
5462</div>
5463
5464<p class="magick-description">replace each pixel with its complementary color.</p>
5465
5466<p>The red, green, and blue intensities of an image are negated. White becomes
5467black, yellow becomes blue, etc. Use <a href="command-line-options.html#negate">+negate</a> to only
5468negate the grayscale pixels of the image.</p>
5469
5470<div style="margin: auto;">
5471 <h4><a id="noise"></a>-noise <var>geometry</var><br>
5472 +noise <var>type</var></h4>
5473</div>
5474
5475<p class="magick-description">Add or reduce noise in an image.</p>
5476
5477<p>The principal function of noise peak elimination filter is to smooth the
5478objects within an image without losing edge information and without creating
5479undesired structures. The central idea of the algorithm is to replace a pixel
5480with its next neighbor in value within a pixel window, if this pixel has been
5481found to be noise. A pixel is defined as noise if and only if this pixel is
5482a maximum or minimum within the pixel window.</p>
5483
5484<p>Use <code><a href="command-line-options.html#noise">-noise</a> <var>radius</var></code> to
5485specify the width of the neighborhood when reducing noise. This is equivalent
5486to using a <code><a href="command-line-options.html#statistic">-statistic</a> NonPeak</code> operation,
5487which should be used in preference.</p>
5488
5489<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
5490types:</p>
5491
5492<pre>
5493 Gaussian
5494 Impulse
5495 Laplacian
5496 Multiplicative
5497 Poisson
5498 Random
5499 Uniform
5500</pre>
5501
5502<p>The amount of noise added can be controled by the <code><a href="command-line-options.html#attunuuate">-attenuate</a></code> setting. If unset the value is
5503equivalent to 1.0, or a maximum noise addition.</p>
5504
5505<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>
5506
5507<p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
5508
5509<p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
5510the use of a controlling value to specify the amount of noise that should be
5511added to an image. </p>
5512
5513
5514<div style="margin: auto;">
5515 <h4><a id="normalize"></a>-normalize</h4>
5516</div>
5517
5518<p class="magick-description">Increase the contrast in an image by <var>stretching</var> the range of intensity values.</p>
5519
5520<p>The intensity values are stretched to cover the entire range of possible
5521values. While doing so, black-out at most <var>2%</var> of the pixels and
5522white-out at most <var>1%</var> of the pixels.</p>
5523
5524<p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize">-normalize</a>
5525is equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x1%</a>.
5526(Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch">-contrast-stretch 2%x99%</a>).</p>
5527
5528<p>All the channels are normalized in concert by the came amount so as to
5529preserve color integrity, when the default <a href="command-line-options.html#channel">+channel</a>
5530setting is in use. Specifying any other <a href="command-line-options.html#channel">-channel</a>
5531setting will normalize the RGB channels independently.</p>
5532
5533<p>See <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> for more details.
5534Also see <a href="command-line-options.html#auto-level">-auto-level</a> for a 'perfect' normalization
5535that is better suited to mathematically generated images. </p>
5536
5537<p>This operator is under review for re-development. </p>
5538
5539
5540<div style="margin: auto;">
5541 <h4><a id="opaque"></a>-opaque <var>color</var></h4>
5542</div>
5543
5544<p class="magick-description">change this color to the fill color within the image.</p>
5545
5546<p>The <var>color</var> argument is defined using the format
5547described 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
5548given.</p>
5549
5550<p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
5551the target color. </p>
5552
5553<p>The <a href="command-line-options.html#transparent">-transparent</a> operator is exactly the same
5554as <a href="command-line-options.html#opaque">-opaque</a> but replaces the matching color with
5555transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
5556To ensure that it can do this it also ensures that the image has an alpha
5557channel enabled, as per "<code><a href="command-line-options.html#alpha">-alpha</a> set</code>", for
5558the 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>
5559
5560
5561<div style="margin: auto;">
5562 <h4><a id="ordered-dither"></a>-ordered-dither <var>threshold_map</var>{,<var>level</var>...}</h4>
5563</div>
5564
5565<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
5566given number of <var>levels</var> per color channel.</p>
5567
5568<p>You can choose from these standard threshold maps:</p>
5569
5570<pre>
5571 threshold 1x1 Threshold 1x1 (non-dither)
5572 checks 2x1 Checkerboard 2x1 (dither)
5573 o2x2 2x2 Ordered 2x2 (dispersed)
5574 o3x3 3x3 Ordered 3x3 (dispersed)
5575 o4x4 4x4 Ordered 4x4 (dispersed)
5576 o8x8 8x8 Ordered 8x8 (dispersed)
5577 h4x4a 4x1 Halftone 4x4 (angled)
5578 h6x6a 6x1 Halftone 6x6 (angled)
5579 h8x8a 8x1 Halftone 8x8 (angled)
5580 h4x4o Halftone 4x4 (orthogonal)
5581 h6x6o Halftone 6x6 (orthogonal)
5582 h8x8o Halftone 8x8 (orthogonal)
5583 h16x16o Halftone 16x16 (orthogonal)
5584 c5x5b c5x5 Circles 5x5 (black)
5585 c5x5w Circles 5x5 (white)
5586 c6x6b c6x6 Circles 6x6 (black)
5587 c6x6w Circles 6x6 (white)
5588 c7x7b c7x7 Circles 7x7 (black)
5589 c7x7w Circles 7x7 (white)
5590</pre>
5591
5592<p> The <code>threshold</code> generated a simple 50% threshold of the image.
5593This 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.
5594</p>
5595
5596<p>The <code>checks</code> pattern produces a 3 level checkerboard dither
5597pattern. That is a grayscale will become a pattern of solid black, solid
5598white, and mid-tone colors into a checkerboard pattern of black and white.
5599</p>
5600
5601<p>You can define your own <var>threshold map</var> for ordered
5602dithering and halftoning your images, in either personal or system
5603<code>thresholds.xml</code> XML file. See <a href="resources.html">Resources</a>
5604for more details of configuration files. </p>
5605
5606<p>To print a complete list of the thresholds that have been defined, use the
5607<a href="command-line-options.html#list">-list threshold</a> option.</p>
5608
5609<p>Note that at this time the same threshold dithering map is used for all
5610color channels, no attempt is made to offset or rotate the map for different
5611channels is made, to create an offset printing effect. Also as the maps are
5612simple threshold levels, the halftone and circle maps will create incomplete
5613circles along the edges of a colored area. Also all the effects are purely
5614on/off boolean effects, without anti-aliasing to make the circles smooth
5615looking. Large dots can be made to look better with a small amount of blurring
5616after being created. </p>
5617
5618
5619<div style="margin: auto;">
5620 <h4><a id="orient"></a>-orient <var>image orientation</var></h4>
5621</div>
5622
5623<p class="magick-description">specify orientation of a digital camera image.</p>
5624
5625<p>Choose from these orientations:</p>
5626
5627<pre>
5628 bottom-left
5629 bottom-right
5630 left-bottom
5631 left-top
5632 right-bottom
5633 right-top
5634 top-left
5635 top-right
5636 undefined
5637</pre>
5638
5639<p>To print a complete list of orientations, use the <a href="command-line-options.html#list">-list
5640orientation</a> option.</p>
5641
5642
5643<div style="margin: auto;">
5644 <h4><a id="page"></a>-page <var>geometry</var><br>
5645 -page <var>media</var>[<var>offset</var>][{<var>^!&lt;&gt;</var>}]<br>
5646 +page
5647 </h4>
5648</div>
5649
5650<p class="magick-description">Set the size and location of an image on the larger virtual canvas.</p>
5651
5652<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5653
5654<p>For convenience you can specify the page size using <var>media</var> (see below). Offsets can then be added as with other
5655<var>geometry</var> arguments (e.g. <a href="command-line-options.html#page">-page</a> <code>Letter+43+43</code>).</p>
5656
5657<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.
5658The choices for a PostScript page are:</p>
5659
5660<div class="table-responsive">
5661<table class="table table-condensed table-striped">
5662 <tr>
5663 <td><var>media</var></td>
5664 <td><var>width</var></td>
5665 <td><var>height</var></td>
5666 </tr>
5667<tr><td> 11x17 </td> <td align="right"> 792</td> <td align="right"> 1224</td> </tr>
5668<tr><td> Ledger </td> <td align="right"> 1224</td> <td align="right"> 792</td> </tr>
5669<tr><td> Legal </td> <td align="right"> 612</td> <td align="right"> 1008</td> </tr>
5670<tr><td> Letter </td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
5671<tr><td> LetterSmall</td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
5672<tr><td> ArchE </td> <td align="right"> 2592</td> <td align="right"> 3456</td> </tr>
5673<tr><td> ArchD </td> <td align="right"> 1728</td> <td align="right"> 2592</td> </tr>
5674<tr><td> ArchC </td> <td align="right"> 1296</td> <td align="right"> 1728</td> </tr>
5675<tr><td> ArchB </td> <td align="right"> 864</td> <td align="right"> 1296</td> </tr>
5676<tr><td> ArchA </td> <td align="right"> 648</td> <td align="right"> 864</td> </tr>
5677<tr><td> A0 </td> <td align="right"> 2380</td> <td align="right"> 3368</td> </tr>
5678<tr><td> A1 </td> <td align="right"> 1684</td> <td align="right"> 2380</td> </tr>
5679<tr><td> A2 </td> <td align="right"> 1190</td> <td align="right"> 1684</td> </tr>
5680<tr><td> A3 </td> <td align="right"> 842</td> <td align="right"> 1190</td> </tr>
5681<tr><td> A4 </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
5682<tr><td> A4Small </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
5683<tr><td> A5 </td> <td align="right"> 421</td> <td align="right"> 595</td> </tr>
5684<tr><td> A6 </td> <td align="right"> 297</td> <td align="right"> 421</td> </tr>
5685<tr><td> A7 </td> <td align="right"> 210</td> <td align="right"> 297</td> </tr>
5686<tr><td> A8 </td> <td align="right"> 148</td> <td align="right"> 210</td> </tr>
5687<tr><td> A9 </td> <td align="right"> 105</td> <td align="right"> 148</td> </tr>
5688<tr><td> A10 </td> <td align="right"> 74</td> <td align="right"> 105</td> </tr>
5689<tr><td> B0 </td> <td align="right"> 2836</td> <td align="right"> 4008</td> </tr>
5690<tr><td> B1 </td> <td align="right"> 2004</td> <td align="right"> 2836</td> </tr>
5691<tr><td> B2 </td> <td align="right"> 1418</td> <td align="right"> 2004</td> </tr>
5692<tr><td> B3 </td> <td align="right"> 1002</td> <td align="right"> 1418</td> </tr>
5693<tr><td> B4 </td> <td align="right"> 709</td> <td align="right"> 1002</td> </tr>
5694<tr><td> B5 </td> <td align="right"> 501</td> <td align="right"> 709</td> </tr>
5695<tr><td> C0 </td> <td align="right"> 2600</td> <td align="right"> 3677</td> </tr>
5696<tr><td> C1 </td> <td align="right"> 1837</td> <td align="right"> 2600</td> </tr>
5697<tr><td> C2 </td> <td align="right"> 1298</td> <td align="right"> 1837</td> </tr>
5698<tr><td> C3 </td> <td align="right"> 918</td> <td align="right"> 1298</td> </tr>
5699<tr><td> C4 </td> <td align="right"> 649</td> <td align="right"> 918</td> </tr>
5700<tr><td> C5 </td> <td align="right"> 459</td> <td align="right"> 649</td> </tr>
5701<tr><td> C6 </td> <td align="right"> 323</td> <td align="right"> 459</td> </tr>
5702<tr><td> Flsa </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
5703<tr><td> Flse </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
5704<tr><td> HalfLetter </td> <td align="right"> 396</td> <td align="right"> 612</td> </tr>
5705</table></div>
5706
5707<p>This option is also used to place subimages when writing to a multi-image
5708format that supports offsets, such as GIF89 and MNG. When used for this
5709purpose the offsets are always measured from the top left corner of the canvas
5710and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
5711position 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
5712file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
5713the sequence with nonzero width and height defines the width and height values
5714that are written in the <code>MHDR</code> chunk. Otherwise, the MNG width and
5715height are computed from the bounding box that contains all images in the
5716sequence. When writing a GIF89 file, only the bounding box method is used to
5717determine its dimensions.</p>
5718
5719<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
5720left-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
5721page. If the image size exceeds the PostScript page, it is reduced to fit the
5722page. 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
5723corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
5724present with a value other than <var>NorthWest</var>.</p>
5725
5726<p>The default page dimensions for a TEXT image is 612x792.</p>
5727
5728<p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
5729
5730<p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
5731
5732<div style="margin: auto;">
5733 <h4><a id="paint"></a>-paint <var>radius</var></h4>
5734</div>
5735
5736<p class="magick-description">simulate an oil painting.</p>
5737
5738<p>Each pixel is replaced by the most frequent color in a circular
5739neighborhood whose width is specified with <var>radius</var>.</p>
5740
5741<div style="margin: auto;">
5742 <h4><a id="path"></a>-path <var>path</var></h4></div>
5743
5744<p class="magick-description">write images to this path on disk.</p>
5745
5746<div style="margin: auto;">
5747 <h4><a id="pause_animate_"></a>-pause <var>seconds</var></h4>
5748</div>
5749
5750<p class="magick-description">Pause between animation loops</p>
5751
5752<p>Pause for the specified number of seconds before repeating the animation.</p>
5753
5754<div style="margin: auto;">
5755 <h4><a id="pause_import_"></a>-pause <var>seconds</var></h4>
5756</div>
5757
5758<p class="magick-description">Pause between snapshots.</p>
5759
5760<p>Pause for the specified number of seconds before taking the next snapshot.</p>
5761
5762<div style="margin: auto;">
5763 <h4><a id="perceptible"></a>-perceptible <var>epsilon</var></h4>
5764</div>
5765
5766<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>
5767
5768<div style="margin: auto;">
5769 <h4><a id="ping"></a>-ping</h4>
5770</div>
5771
5772<p class="magick-description">efficiently determine image characteristics.</p>
5773
5774<div style="margin: auto;">
5775 <h4><a id="pointsize"></a>-pointsize <var>value</var></h4>
5776</div>
5777
5778<p class="magick-description">pointsize of the PostScript, OPTION1, or TrueType font.</p>
5779
5780<div style="margin: auto;">
5781 <h4><a id="polaroid"></a>-polaroid <var>angle</var></h4>
5782</div>
5783
5784<p class="magick-description">simulate a Polaroid picture.</p>
5785
5786<p>Use <code>+polaroid</code> to rotate the image at a random angle between -15 and +15 degrees.</p>
5787
5788<div style="margin: auto;">
5789 <h4><a id="poly"></a>-poly <var>"wt,exp ..."</var></h4>
5790</div>
5791
5792<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>
5793
5794<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>
5795
5796<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>
5797
5798<p>The format is: output = wt1*image1^exp1 + wt2*image2^exp2 ...</p>
5799
5800<p>Some simple uses are:</p>
5801<ul>
5802<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>
5803<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>
5804</ul>
5805
5806<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>
5807
5808<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>
5809
5810
5811<div style="margin: auto;">
5812 <h4><a id="posterize"></a>-posterize <var>levels</var></h4>
5813</div>
5814
5815<p class="magick-description">reduce the image to a limited number of color levels per channel.</p>
5816
5817<p>Very low values of <var>levels</var>, e.g., 2, 3, 4, have the most
5818visible effect.</p>
5819
5820<div style="margin: auto;">
5821 <h4><a id="precision"></a>-precision <var>value</var></h4>
5822</div>
5823
5824<p class="magick-description">set the maximum number of significant digits to be printed.</p>
5825
5826<div style="margin: auto;">
5827 <h4><a id="preview"></a>-preview <var>type</var></h4>
5828</div>
5829
5830<p class="magick-description">image preview type.</p>
5831
5832<p>Use this option to affect the preview operation of an image (e.g.
5833<code>convert file.png -preview Gamma Preview:gamma.png</code>). Choose from
5834these previews:</p>
5835
5836<pre>
5837 Rotate Shear Roll Hue
5838 Saturation Brightness Gamma Spiff
5839 Dull Grayscale Quantize Despeckle
5840 ReduceNoise Add Noise Sharpen Blur
5841 Threshold EdgeDetect Spread Shade
5842 Raise Segment Solarize Swirl
5843 Implode Wave OilPaint CharcoalDrawing
5844 JPEG
5845</pre>
5846
5847<p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
5848
5849<p>The default preview is <code>JPEG</code>.</p>
5850
5851<div style="margin: auto;">
5852 <h4><a id="print"></a>-print <var>string</var></h4>
5853</div>
5854
5855<p class="magick-description">interpret string and print to console.</p>
5856
5857<div style="margin: auto;">
5858 <h4><a id="process"></a>-process <var>command</var></h4>
5859</div>
5860
5861<p class="magick-description">process the image with a custom image filter.</p>
5862
5863<p>The command arguments has the form <code>"module arg1 arg2 arg3 ...
5864argN"</code> where <code>module</code> is the name of the module to invoke (e.g.
5865"Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
5866pass to the process module.</p>
5867
5868<div style="margin: auto;">
5869 <h4><a id="profile"></a>-profile <var>filename</var><br>
5870 +profile <var>profile_name</var></h4>
5871</div>
5872
5873<p class="magick-description">Manage ICM, IPTC, or generic profiles in an image.</p>
5874
5875<p>Using <a href="command-line-options.html#profile">-profile</a> <var>filename</var> adds an
5876ICM (ICC color management), IPTC (newswire information), or a generic profile
5877to the image.</p>
5878
5879<p>Use <a href="command-line-options.html#profile">+profile <var>profile_name</var></a> to
5880remove the indicated profile. ImageMagick uses standard filename globbing, so
5881wildcard expressions may be used to remove more than one profile. Here we
5882remove all profiles from the image except for the XMP profile: <code>+profile
5883"!xmp,*"</code>. </p>
5884
5885<p>Use <code>identify -verbose</code> to find out which profiles are in the
5886image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
5887comments).</p>
5888
5889<p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
5890used. Instead, simply write the file to an image format such as <var>APP1, 8BIM, ICM,</var> or <var>IPTC</var>.</p>
5891
5892<p>For example, to extract the Exif data (which is stored in JPEG files in the
5893<var>APP1</var> profile), use.</p>
5894
5895<pre>
5896convert cockatoo.jpg profile.exif
5897</pre>
5898
5899<p>It is important to note that results may depend on whether or not the
5900original 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
5901therefore a conversion is made each time it is encountered, in order, in the
5902command-line. For instance, in the following example, if the original image is
5903CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
5904
5905<pre>
5906convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff
5907</pre>
5908
5909<p>Furthermore, since ICC profiles are not necessarily symmetric, extra
5910conversion steps can yield unwanted results. CMYK profiles are often very
5911asymmetric since they involve 3−&gt;4 and 4−&gt;3 channel mapping.
5912</p>
5913
5914<div style="margin: auto;">
5915 <h4><a id="quality"></a>-quality <var>value</var></h4>
5916</div>
5917
5918<p class="magick-description">JPEG/MIFF/PNG compression level.</p>
5919
5920<p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
5921highest compression) to 100 (best quality but least effective compression).
5922The default is to use the estimated quality of your input image if it can
5923be determined, otherwise 92. When the quality is greater than 90, then the
5924chroma channels are not downsampled.
5925Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
5926factors for chroma downsampling.</p>
5927
5928<p>For the MIFF image format, quality/10 is the zlib compression level, which
5929is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect
5930on the image appearance, since the compression is always lossless.</p>
5931
5932<p>For the JPEG-2000 image format, quality is mapped using a non-linear
5933equation to the compression ratio required by the Jasper library. This
5934non-linear equation is intended to loosely approximate the quality provided by
5935the JPEG v1 format. The default quality value 100, a request for non-lossy
5936compression. A quality of 75 results in a request for 16:1 compression.</p>
5937
5938<p>For the MNG and PNG image formats, the quality value sets the zlib
5939compression level (quality / 10) and filter-type (quality % 10). The default
5940PNG "quality" is 75, which means compression level 7 with adaptive PNG
5941filtering, unless the image has a color map, in which case it means
5942compression level 7 with no PNG filtering.</p>
5943
5944<p>For compression level 0 (quality value less than 10), the Huffman-only
5945strategy is used, which is fastest but not necessarily the worst
5946compression.</p>
5947
5948<p>If filter-type is 4 or less, the specified PNG filter-type is used for
5949all scanlines:</p>
5950
5951<pre>
5952 0: none
5953 1: sub
5954 2: up
5955 3: average
5956 4: Paeth
5957</pre>
5958
5959<p>If filter-type is 5, adaptive filtering is used when quality is greater
5960than 50 and the image does not have a color map, otherwise no filtering is
5961used.</p>
5962
5963<p>If filter-type is 6, adaptive filtering
5964with <var>minimum-sum-of-absolute-values</var> is used.</p>
5965
5966<p>Only if the output is MNG, if filter-type is 7, the LOCO color
5967transformation (intrapixel differencing) and adaptive filtering
5968with <var>minimum-sum-of-absolute-values</var> are used.</p>
5969
5970<p>If the filter-type is 8 the zlib Z_RLE compression strategy (or the
5971Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
5972adaptive PNG filtering.</p>
5973
5974<p>If the filter-type is 9 the zlib Z_RLE compression strategy (or the
5975Z_HUFFMAN_ONLY strategy, when compression level is 0) is used with
5976no PNG filtering.</p>
5977
5978<p>The quality setting has no effect on the appearance or signature of PNG
5979and MNG images, since the compression is always lossless.</p>
5980
5981<p>Not all combinations of compression level, strategy, and PNG filter type
5982can be obtained using the -quality option. For more precise control,
5983you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
5984PNG:compression-filter=N defines, respectively, instead.
5985See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
5986over values from the -quality option.</p>
5987
5988<p>For further information, see
5989the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
5990
5991<div style="margin: auto;">
5992 <h4><a id="quantize"></a>-quantize <var>colorspace</var></h4>
5993</div>
5994
5995<p class="magick-description">reduce colors using this colorspace.</p>
5996
5997<p>This setting defines the colorspace used to sort out and reduce the number
5998of 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
5999automatically when saving images to color-limited image file formats, such as
6000GIF, and PNG8.</p>
6001
6002
6003<div style="margin: auto;">
6004 <h4><a id="quiet"></a>-quiet</h4>
6005</div>
6006
6007<p class="magick-description">suppress all warning messages. Error messages are still reported.</p>
6008
6009<div style="margin: auto;">
6010 <h4><a id="radial-blur"></a>-radial-blur <var>angle</var></h4>
6011</div>
6012
6013<p class="magick-description">Blur around the center of the image.</p>
6014
6015<p>Note that this is actually a rotational blur rather than a radial and as
6016such actually mis-named. </p>
6017
6018<p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
6019pixels which are outside the image proper are blurred into the final result.
6020</p>
6021
6022
6023<div style="margin: auto;">
6024 <h4><a id="raise"></a>-raise <var>thickness</var></h4>
6025</div>
6026
6027<p class="magick-description">Lighten or darken image edges.</p>
6028
6029<p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
6030a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>. </p>
6031
6032<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>
6033
6034<div style="margin: auto;">
6035 <h4><a id="random-threshold"></a>-random-threshold <var>low</var>x<var>high</var></h4>
6036</div>
6037
6038<p class="magick-description">Apply a random threshold to the image.</p>
6039
6040<div style="margin: auto;">
6041 <h4><a id="red-primary"></a>-red-primary <var>x,y</var></h4>
6042</div>
6043
6044<p class="magick-description">Set the red chromaticity primary point.</p>
6045
6046<div style="margin: auto;">
6047 <h4><a id="regard-warnings"></a>-regard-warnings</h4>
6048</div>
6049
6050<p class="magick-description">Pay attention to warning messages.</p>
6051
6052<p>This option causes some warnings in some image formats to be treated
6053as errors. </p>
6054
6055<div style="margin: auto;">
6056 <h4><a id="remap"></a>-remap <var>filename</var></h4>
6057</div>
6058
6059<p class="magick-description">Reduce the number of colors in an image to the colors used by this image.</p>
6060
6061<p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
6062the given colors are dithered over the image as necessary, otherwise the closest
6063color (in RGB colorspace) is selected to replace that pixel in the image. </p>
6064
6065<p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
6066images in the current image sequence, all the images will have the same color
6067table. That means that when saved to a file format such as GIF, it will use
6068that color table as a single common or global color table, for all the images,
6069without requiring extra local color tables. </p>
6070
6071<p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
6072sequence to use a common color map over all the images. This equivalent to
6073appending all the images together (without extra background colors) and color
6074reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
6075limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
6076images. This ensures all the images follow a single color map. </p>
6077
6078<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
6079no color changes are needed. In that case, its only effect is to force the use
6080of 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
6081reduce the number of colors in an animated image sequence. </p>
6082
6083<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>
6084
6085<div style="margin: auto;">
6086 <h4><a id="region"></a>-region <var>geometry</var></h4>
6087</div>
6088
6089<p class="magick-description">Set a region in which subsequent operations apply.</p>
6090
6091<p>The <var>x</var> and <var>y</var> offsets are treated
6092in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
6093
6094<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6095
6096<div style="margin: auto;">
6097 <h4><a id="remote"></a>-remote</h4>
6098</div>
6099
6100<p class="magick-description">perform a remote operation.</p>
6101
6102<p>The only command recognized is the name of an image file to load.</p>
6103
6104<p>If you have more than one <a href="display.html">display</a> application
6105running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
6106specify which application to control.</p>
6107
6108<div style="margin: auto;">
6109 <h4><a id="render"></a>-render</h4>
6110</div>
6111
6112<p class="magick-description">render vector operations.</p>
6113
6114<p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
6115This useful when saving the result to vector formats such as MVG or SVG.</p>
6116
6117<div style="margin: auto;">
6118<h4><a id="repage"></a>-repage <var>geometry</var></h4>
6119</div>
6120
6121<p class="magick-description">Adjust the canvas and offset information of the image.</p>
6122
6123<p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
6124rather than a setting. You can separately set the canvas size or the offset
6125of the image on that canvas by only providing those components. </p>
6126
6127<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6128
6129<p>If a <code>!</code> flag is given the offset given is added to the existing
6130offset to move the image relative to its previous position. This useful for
6131animation sequences. </p>
6132
6133<p>A given a canvas size of zero such as '<code>0x0</code>' forces it to
6134recalculate the canvas size so the image (at its current offset) will appear
6135completely on that canvas (unless it has a negative offset).</p>
6136
6137<p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
6138canvas meta-data from the images. </p>
6139
6140<p>The <a href="command-line-options.html#set">-set</a> '<code>page</code>' option can be used to
6141directly assign virtual canvas meta-data. </p>
6142
6143
6144<div style="margin: auto;">
6145 <h4><a id="resample"></a>-resample <var>horizontal</var>x<var>vertical</var></h4>
6146</div>
6147
6148<p class="magick-description">Resample image to specified horizontal and vertical resolution.</p>
6149
6150<p>Resize the image so that its rendered size remains the same as the original
6151at the specified target resolution. For example, if a 300 DPI image renders at
61523 inches by 2 inches on a 300 DPI device, when the image has been resampled to
615372 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that
6154only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
6155storing the image resolution. For formats which do not support an image
6156resolution, 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
6157resample resolution.</p>
6158
6159<p>Note that Photoshop stores and obtains image resolution from a proprietary
6160embedded profile. If this profile exists in the image, then Photoshop will
6161continue to treat the image using its former resolution, ignoring the image
6162resolution specified in the standard file header.</p>
6163
6164<div style="margin: auto;">
6165 <h4><a id="resize"></a>-resize <var>geometry</var></h4>
6166</div>
6167
6168<p class="magick-description">Resize an image.</p>
6169
6170<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
6171ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
6172
6173<p>If the <a href="command-line-options.html#filter">-filter</a> option
6174or <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
6175filter.</p>
6176
6177<p>Many image processing algorithms assume your image is in a linear-light
6178coding. If your image is gamma-corrected, you can remove the nonlinear gamma
6179correction, apply the transform, then restore it like this:</p>
6180
6181<pre>
6182convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \ <br> -quality 92 passport.jpg
6183</pre>
6184
6185<div style="margin: auto;">
6186 <h4><a id="respect-parentheses"></a>-respect-parentheses</h4>
6187</div>
6188
6189<p class="magick-description">settings remain in effect until parenthesis boundary.</p>
6190
6191<div style="margin: auto;">
6192 <h4><a id="reverse"></a>-reverse</h4>
6193</div>
6194
6195<p class="magick-description">Reverse the order of images in the current image list.</p>
6196
6197
6198<div style="margin: auto;">
6199 <h4><a id="roll"></a>-roll {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h4>
6200</div>
6201
6202<p class="magick-description">roll an image vertically or horizontally by the amount given.</p>
6203
6204<p>A negative <var>x</var> offset rolls the image right-to-left.
6205A negative <var>y</var> offset rolls the image bottom-to-top.</p>
6206
6207
6208<div style="margin: auto;">
6209 <h4><a id="rotate"></a>-rotate <var>degrees</var>{<var>&lt;</var>}{<var>&gt;</var>}</h4>
6210</div>
6211
6212<p class="magick-description">Apply Paeth image rotation (using shear operations) to the image.</p>
6213
6214<p>Use <code>&gt;</code> to rotate the image only if its width exceeds the
6215height. <code>&lt;</code> rotates the image <var>only</var> if its width is less
6216than the height. For example, if you specify <code>-rotate "-90&gt;"</code> and
6217the image size is 480x640, the image is not rotated. However, if the image is
6218640x480, it is rotated by -90 degrees. If you use <code>&gt;</code> or
6219<code>&lt;</code>, enclose it in quotation marks to prevent it from being
6220misinterpreted as a file redirection.</p>
6221
6222<p>Empty triangles in the corners, left over from rotating the image, are
6223filled with the <code>background</code> color. </p>
6224
6225<p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
6226'<code>ScaleRotateTranslate</code>' distort method. </p>
6227
6228
6229<div style="margin: auto;">
6230 <h4><a id="sample"></a>-sample <var>geometry</var></h4>
6231</div>
6232
6233<p class="magick-description">minify / magnify the image with pixel subsampling and pixel replication, respectively.</p>
6234
6235<p>Change the image size simply by directly sampling the pixels original
6236from the image. When magnifying, pixels are replicated in blocks. When
6237minifying, pixels are sub-sampled (i.e., some rows and columns are skipped
6238over). </p>
6239
6240<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6241a <a href="command-line-options.html#filter">-filter</a> setting of <code>point</code> (nearest
6242neighbour), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
6243avoids all the filter processing of the image. As such it completely ignores
6244the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6245
6246<p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
6247will be added to the resulting image, though some colors may disappear. </p>
6248
6249<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
6250ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
6251
6252
6253<p>The actual sampling point is the middle of the sub-region being sampled.
6254As such a single pixel sampling of an image will take the middle pixel, (or
6255top-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
6256this position some other location within each sub-region being sampled, as
6257a percentage offset.</p>
6258
6259<p>By default this value is '<code>50</code>' for the midpoint, but could be set
6260to '<code>0</code>' for top-left, '<code>100</code>' for bottom-right, or with
6261separate X and Y offsets such as '<code>0x50</code>' for left-middle edge of
6262sampling sub-region.</p>
6263
6264
6265<div style="margin: auto;">
6266 <h4><a id="sampling-factor"></a>-sampling-factor <var>horizontal-factor</var>x<var>vertical-factor</var></h4>
6267</div>
6268
6269<p class="magick-description">sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</p>
6270
6271<p>This option specifies the sampling factors to be used by the JPEG encoder
6272for chroma downsampling. If this option is omitted, the JPEG library will use
6273its own default values. When reading or writing the YUV format and when
6274writing 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
6275downsampling method.</p>
6276
6277<div style="margin: auto;">
6278 <h4><a id="scale"></a>-scale <var>geometry</var></h4>
6279</div>
6280
6281<p class="magick-description">minify / magnify the image with pixel block averaging and pixel replication, respectively.</p>
6282
6283<p>Change the image size simply by replacing pixels by averaging pixels
6284together when minifying, or replacing pixels when magnifying. </p>
6285
6286<p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6287a <a href="command-line-options.html#filter">-filter</a> setting of <code>box</code>. Though it is a lot
6288faster, as it avoids all the filter processing of the image. As such it
6289completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6290
6291<p>If when shrinking (minifying) images the original image is some integer
6292multiple of the new image size, the number of pixels averaged together to
6293produce the new pixel color is the same across the whole image. This is
6294a special case known as 'binning' and is often used as a method of reducing
6295noise in image such as those generated by digital cameras, especially in low
6296light conditions. </p>
6297
6298
6299<div style="margin: auto;">
6300 <h4><a id="scene"></a>-scene <var>value</var></h4>
6301</div>
6302
6303<p class="magick-description">set scene number.</p>
6304
6305<p>This option sets the scene number of an image or the first image in an image sequence.</p>
6306
6307<div style="margin: auto;">
6308 <h4><a id="screen"></a>-screen</h4>
6309</div>
6310
6311<p class="magick-description">specify the screen to capture.</p>
6312
6313<p>This option indicates that the GetImage request used to obtain the image
6314should be done on the root window, rather than directly on the specified
6315window. In this way, you can obtain pieces of other windows that overlap the
6316specified window, and more importantly, you can capture menus or other popups
6317that are independent windows but appear over the specified window.</p>
6318
6319<div style="margin: auto;">
6320 <h4><a id="seed"></a>-seed</h4>
6321</div>
6322
6323<p class="magick-description">seed a new sequence of pseudo-random numbers</p>
6324
6325<div style="margin: auto;">
6326 <h4><a id="segment"></a>-segment <var>cluster-threshold</var>x<var>smoothing-threshold</var></h4>
6327</div>
6328
6329<p class="magick-description">segment the colors of an image.</p>
6330
6331<p>Segment an image by analyzing the histograms of the color components and
6332identifying units that are homogeneous with the fuzzy c-means technique. This
6333is part of the ImageMagick color quantization routines. </p>
6334
6335<p>Specify <var>cluster threshold</var> as the number of pixels in
6336each cluster that must exceed the cluster threshold to be considered valid.
6337<var>Smoothing threshold</var> eliminates noise in the second
6338derivative of the histogram. As the value is increased, you can expect
6339a smoother second derivative. The default is 1.5.</p>
6340
6341<p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6342of the color clusters is returned.</p>
6343
6344
6345<div style="margin: auto;">
6346 <h4><a id="selective-blur"></a>-selective-blur <var>radius</var><br>-selective-blur <var>radius</var>x<var>sigma</var>{<var>+threshold</var>}</h4>
6347</div>
6348
6349<p class="magick-description">Selectively blur pixels within a contrast threshold.</p>
6350
6351<p>Blurs those pixels that are less than or equal to the threshold in
6352contrast. The threshold may be expressed as a fraction of <var>QuantumRange</var> or as a percentage.</p>
6353
6354<div style="margin: auto;">
6355 <h4><a id="separate"></a>-separate</h4>
6356</div>
6357
6358<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>
6359
6360<div style="margin: auto;">
6361 <h4><a id="sepia-tone"></a>-sepia-tone <var>threshold</var></h4>
6362</div>
6363
6364<p class="magick-description">simulate a sepia-toned photo.</p>
6365
6366<p>Specify <var>threshold</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6367
6368<p>This option applies a special effect to the image, similar to the effect
6369achieved 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
6370toning. A threshold of 80% is a good starting point for a reasonable
6371tone.</p>
6372
6373
6374
6375<div style="margin: auto;">
6376 <h4><a id="set"></a>-set <var>key value</var></h4>
6377 <h4>+set <var>key</var></h4>
6378</div>
6379
6380<p class="magick-description">sets image attributes and properties for images in the current image sequence.</p>
6381
6382<p>This will assign (or modify) specific settings attached to all the images
6383in the current image sequence. Using the <a href="command-line-options.html#set">+set</a> form of the
6384option will either remove, or reset that setting to a default state, as
6385appropriate. </p>
6386
6387<p>For example, it will modify specific well known image meta-data
6388'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
6389assigned before the image is read in, by using a <var>key</var> of
6390the same name. </p>
6391
6392<p>If the given <var>key</var> does not match a specific known
6393'attribute ', such as shown above, the setting is stored as a a free form
6394'property' string. Such settings are listed in <a href="command-line-options.html#verbose">-verbose</a> information ("<code>info:</code>" output format) as "Properties".
6395</p>
6396
6397<p>This includes string 'properties' that are set by and assigned to images
6398using 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
6399a global 'artifact' which are automatically assigned (and any <a href="escape.html">Format Percent
6400Escapes</a> expanded) to images as they are read in. For example:</p>
6401
6402<pre>
6403convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png
6404identify -format %c rose.png
6405Rose is a rose is a rose is a rose
6406</pre>
6407
6408<p>The set value can also make use of <a href="escape.html">Format and Print Image
6409Properties</a> in the defined value. For example:</p>
6410
6411<pre>
6412convert rose: -set origsize '%wx%h' -resize 50% \
6413 -format 'Old size = %[origsize] New size = %wx%h' info:
6414Old size = 70x46 New size = 35x23
6415</pre>
6416
6417<p>Other well known 'properties' that are availible include:
6418'<code>date:create</code>' and '<code>date:modify</code>' and
6419'<code>signature</code>'. </p>
6420
6421<p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6422the '<code>page</code>' attribute of an image for images already in memory (also
6423see <a href="command-line-options.html#repage">-page</a>). However it is designed to provide a finer
6424control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6425option will only provide a direct, unmodified assignment of '<code>page</code>'
6426attribute. </p>
6427
6428<p>This option can also associate a colorspace or profile with your image.
6429For example,</p>
6430
6431<pre>
6432convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd
6433</pre>
6434
6435<p>Some 'properties' must be defined in a specific way to be used. For
6436example only 'properties' prefixed with "<code>filename:</code>" can be used to
6437modify the output filename of an image. For example</p>
6438
6439<pre>
6440convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'
6441</pre>
6442
6443<p>If the setting value is prefixed with "<code>option:</code>" the setting will
6444be 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
6445can be used to pass 'attributes' and 'properties' of one specific image,
6446in a way that allows you to use them in a completely different image, even if
6447the original image has long since been modified or destroyed. For example: </p>
6448
6449<pre>
6450convert rose: -set option:rosesize '%wx%h' -delete 0 \
6451 label:'%[rosesize]' label_size_of_rose.gif"
6452</pre>
6453
6454<p>Note that <a href="escape.html">Format Percent Escapes</a> will only match
6455a 'artifact' if the given <var>key</var> does not match an existing
6456'attribute' or 'property'. </p>
6457
6458<p>You can set the attributes of the image registry by prefixing the value
6459with <code>registry:</code>.</p>
6460
6461<p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
6462previously-formatted ancillary chunks into the output PNG file, using
6463the commandline option as shown below or by setting the profile via a
6464programming interface:</p>
6465
6466<pre>
6467convert in.png -set profile PNG-chunk-x:&lt;filename&gt; out.png
6468</pre>
6469
6470<p>where <var>x</var> is a location flag and
6471<var>filename</var> is a file containing the chunk
6472name in the first 4 bytes, then a colon (":"), followed by the chunk data.
6473This encoder will compute the chunk length and CRC, so those must not
6474be included in the file.</p>
6475
6476<p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
6477or "e" (end, i.e., after IDAT). If you want to write multiple chunks
6478of the same type, then add a short unique string after the "x" to prevent
6479subsequent profiles from overwriting the preceding ones, e.g.,</p>
6480
6481
6482<pre>
6483convert in.png -set profile PNG-chunk-b01:file01 \
6484 -profile PNG-chunk-b02:file02 out.png
6485</pre>
6486
6487<div style="margin: auto;">
6488 <h4><a id="shade"></a>-shade <var>azimuth</var>x<var>elevation</var></h4>
6489</div>
6490
6491<p class="magick-description">shade the image using a distant light source.</p>
6492
6493<p>Specify <var>azimuth</var> and <var>elevation</var> as
6494the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
6495the shading results as a grayscale image.</p>
6496
6497<div style="margin: auto;">
6498 <h4><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>}</h4>
6499</div>
6500
6501<p class="magick-description">simulate an image shadow.</p>
6502
6503<div style="margin: auto;">
6504 <h4><a id="shared-memory"></a>-shared-memory</h4>
6505</div>
6506
6507<p class="magick-description">use shared memory.</p>
6508
6509<p>This option specifies whether the utility should attempt to use shared
6510memory for pixmaps. ImageMagick must be compiled with shared memory support,
6511and the display must support the <var>MIT-SHM</var> extension.
6512Otherwise, this option is ignored. The default is <code>True</code>.</p>
6513
6514<div style="margin: auto;">
6515 <h4><a id="sharpen"></a>-sharpen <var>radius</var><br>-sharpen <var>radius</var>x<var>sigma</var></h4>
6516</div>
6517
6518<p class="magick-description">sharpen the image.</p>
6519
6520<p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
6521
6522<div style="margin: auto;">
6523 <h4><a id="shave"></a>-shave <var>geometry</var></h4>
6524</div>
6525
6526<p class="magick-description">Shave pixels from the image edges.</p>
6527
6528<p>The <var>size</var> portion of the <var>geometry</var>
6529argument specifies the width of the region to be removed from both sides of
6530the image and the height of the regions to be removed from top and bottom.
6531Offsets are ignored.</p>
6532
6533<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6534
6535<div style="margin: auto;">
6536 <h4><a id="shear"></a>-shear <var>Xdegrees</var>[x<var>Ydegrees</var>]</h4>
6537</div>
6538
6539<p class="magick-description">Shear the image along the x-axis and/or y-axis.</p>
6540
6541<p>The shear angles may be positive, negative, or zero. When <var>Ydegrees</var> is omitted it defaults to 0. When both angles are
6542given, the horizontal component of the shear is performed before the vertical
6543component.</p>
6544
6545<p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
6546horizontally or vertically, respectively),creating a parallelogram. The amount
6547of each is controlled by the respective shear angle. For horizontal shears,
6548<var>Xdegrees</var> is measured clockwise relative to "up" (the
6549negative 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
6550positive 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>
6551
6552<p>Empty triangles left over from shearing the image are filled with the color
6553defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
6554using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6555
6556<p>The horizontal shear is performed before the vertical part. This is
6557important to note, since horizontal and vertical shears do not
6558<var>commute</var>, i.e., the order matters in a sequence of shears. For
6559example, the following two commands are not equivalent.</p>
6560
6561<pre>
6562convert logo: -shear 20x0 -shear 0x60 logo-sheared.png
6563convert logo: -shear 0x60 -shear 20x0 logo-sheared.png
6564</pre>
6565
6566<p>The first of the two commands above is equivalent to the following, except
6567for the amount of empty space created; the command that follows generates
6568a smaller image, and so is a better choice in terms of time and space.</p>
6569
6570<pre>
6571convert logo: -shear 20x60 logo-sheared.png
6572</pre>
6573
6574<div style="margin: auto;">
6575 <h4><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <var>contrast</var>x<var>mid-point</var></h4>
6576</div>
6577
6578<p class="magick-description">increase the contrast without saturating highlights or shadows.</p>
6579
6580<p>Increase the contrast of the image using a sigmoidal transfer function
6581without saturating highlights or shadows. <var>Contrast</var>
6582indicates how much to increase the contrast. For example, 0 is none, 3 is
6583typical and 20 is a lot.
6584</p>
6585
6586<p>The <var>mid-point</var> indicates where the maximum change
6587'slope' in contrast should fall in the resultant image (0 is white; 50% is
6588middle-gray; 100% is black). </p>
6589
6590<p>By default the image contrast is increased, use <var>+sigmoidal-contrast</var> to decrease the contrast.</p>
6591
6592<p>To achieve the equivalent of a sigmoidal brightness change (similar to
6593a gamma adjustment), you would use <var>-sigmoidal-contrast
6594{brightness}x0%</var> to increase brightness and <var>+sigmoidal-contrast {brightness}x0%</var> to decrease brightness.
6595Note the use of '0' fo rthe mid-point of the sigmoidal curve. </p>
6596
6597<p>Using a very high <var>contrast</var> will produce a sort of
6598'smoothed thresholding' of the image. Not as sharp (with high aliasing
6599effects) of a true threshold, but with tapered gray-levels around the threshold
6600<var>mid-point</var>. </p>
6601
6602<div style="margin: auto;">
6603 <h4><a id="silent"></a>-silent</h4>
6604</div>
6605
6606<p class="magick-description">operate silently.</p>
6607
6608<div style="margin: auto;">
6609 <h4><a id="similarity-threshold"></a>-similarity-threshold <var>value</var></h4>
6610</div>
6611
6612<p class="magick-description">minimum RMSE for subimage match.</p>
6613
6614<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>
6615
6616<div style="margin: auto;">
6617 <h4><a id="size"></a>-size <var>width</var>[x<var>height</var>][<var>+offset</var>]</h4>
6618</div>
6619
6620<p class="magick-description">set the width and height of the image.</p>
6621
6622<p>Use this option to specify the width and height of raw images whose
6623dimensions are unknown such as <code>GRAY</code>, <code>RGB</code>, or
6624<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
6625image or tell the number of colors in a <code>MAP</code> image file, (e.g. -size
6626640x512+256).</p>
6627
6628<p>For Photo CD images, choose from these sizes:</p>
6629
6630<pre>
6631 192x128
6632 384x256
6633 768x512
6634 1536x1024
6635 3072x2048
6636</pre>
6637
6638<div style="margin: auto;">
6639 <h4><a id="sketch"></a>-sketch <var>radius</var><br>-sketch <var>radius</var>x<var>sigma</var>+<var>angle</var></h4>
6640</div>
6641
6642<p class="magick-description">simulate a pencil sketch.</p>
6643
6644<p>Sketch with the given radius, standard deviation (sigma), and angle. The
6645angle given is the angle toward which the image is sketched. That is the
6646direction people would consider the object is coming from. </p>
6647
6648<div style="margin: auto;">
6649 <h4><a id="smush"></a>-smush <var>offset</var></h4>
6650</div>
6651
6652<p class="magick-description">smush an image sequence together.</p>
6653
6654<div style="margin: auto;">
6655 <h4><a id="snaps"></a>-snaps <var>value</var></h4>
6656</div>
6657
6658<p class="magick-description">Set the number of screen snapshots.</p>
6659
6660<p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
6661
6662<div style="margin: auto;">
6663 <h4><a id="solarize"></a>-solarize <var>threshold</var></h4>
6664</div>
6665
6666<p class="magick-description">negate all pixels above the threshold level.</p>
6667
6668<p>Specify <var>factor</var> as the percent threshold of the intensity (0 - 99.9%).</p>
6669
6670<p>This option produces a <var>solarization</var> effect seen when
6671exposing a photographic film to light during the development process.</p>
6672
6673<div style="margin: auto;">
6674 <h4><a id="sparse-color"></a>-sparse-color <var>method</var> '<var>x</var>,<var>y</var> <var>color</var> ...'</h4>
6675</div>
6676
6677<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>
6678
6679
6680<table class="table table-condensed table-striped">
6681 <tbody>
6682 <tr>
6683 <th style="width: 8%">Method</th>
6684 <th>Description</th>
6685 </tr>
6686
6687 <tr>
6688 <td>barycentric</td>
6689 <td>three point triangle of color given 3 points.
6690 Giving only 2 points will form a linear gradient between those points.
6691 The gradient generated extends beyond the triangle created by those
6692 3 points. </td>
6693 </tr>
6694
6695 <tr>
6696 <td>bilinear</td>
6697 <td>Like barycentric but for 4 points. Less than 4 points
6698 fall back to barycentric. </td>
6699 </tr>
6700 <tr>
6701 <td>voronoi</td>
6702 <td>Simply map each pixel to the to nearest color point
6703 given. The result are polygonal 'cells' of solid color. </td>
6704 </tr>
6705
6706 <tr>
6707 <td>shepards</td>
6708 <td>Colors points biased on the ratio of inverse distance
6709 squared. Generating spots of color in a sea of the average of
6710 colors. </td>
6711 </tr>
6712
6713 <tr>
6714 <td>inverse</td>
6715 <td>Colors points biased on the ratio of inverse distance.
6716 This generates sharper points of color rather than rounded spots of
6717 '<code>shepards</code>' Generating spots of color in a sea of the
6718 average of colors. </td>
6719 </tr>
6720
6721 </tbody>
6722</table>
6723
6724<p>The points are placed according to the images location on the virtual
6725canvas (<a href="command-line-options.html#page">-page</a> or <a href="command-line-options.html#repage">-repage</a>
6726offset), and do not actually have to exist on the given image, but may be
6727some point beyond the edge of the image. All points are floating point values.
6728</p>
6729
6730<p>Only the color channels defined by the <a href="command-line-options.html#channel">-channel</a> are
6731modified, which means that by default matte/alpha transparency channel is not
6732effected. Typically transparency channel is turned off either before or after
6733the operation. </p>
6734
6735<p>Of course if some color points are transparent to generate a transparent
6736gradient, then the image also requires transparency enabled to store the
6737values. </p>
6738
6739<p>All the above methods when given a single point of color will replace all
6740the colors in the image with the color given, regardless of the point. This is
6741logical, and provides an alternative technique to recolor an image to some
6742default value. </p>
6743
6744
6745<div style="margin: auto;">
6746 <h4><a id="splice"></a>-splice <var>geometry</var></h4>
6747</div>
6748
6749<p class="magick-description">Splice the current background color into the image.</p>
6750
6751<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
6752given <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
6753image into four quadrants, separating them by the inserted rows and columns.
6754</p>
6755
6756<p>If a dimension of geometry is zero no rows or columns will be added for that
6757dimension. 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
6758the 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>
6759
6760<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
6761added added all splices removed. </p>
6762
6763<div style="margin: auto;">
6764 <h4><a id="spread"></a>-spread <var>amount</var></h4>
6765</div>
6766
6767<p class="magick-description">displace image pixels by a random amount.</p>
6768
6769<p>The argument <var>amount</var> defines the size of the
6770neighborhood around each pixel from which to choose a candidate pixel to
6771swap.</p>
6772
6773<div style="margin: auto;">
6774 <h4><a id="statistic"></a>-statistic <var>type</var> <var>geometry</var></h4>
6775</div>
6776
6777<p class="magick-description">replace each pixel with corresponding statistic from the neighborhood.</p>
6778
6779<p>Choose from these statistic types:</p>
6780<pre>
6781 Gradient maximum difference (max - min) value in neighborhood
6782 Maximum maximum value per channel in neighborhood
6783 Minimum minimum value per channel in neighborhood
6784 Mean average value per channel in neighborhood
6785 Median median value per channel in neighborhood
6786 Mode mode (most frequent) value per channel in neighborhood
6787 Nonpeak value just before or after the median value per channel in neighborhood
6788 RMS root mean square value per channel in neighborhood
6789 StandardDeviation standard deviation value per channel in neighborhood
6790</pre>
6791
6792<div style="margin: auto;">
6793 <h4><a id="stegano"></a>-stegano <var>offset</var></h4>
6794</div>
6795
6796<p class="magick-description">hide watermark within an image.</p>
6797
6798<p>Use an offset to start the image hiding some number of pixels from the
6799beginning of the image. Note this offset and the image size. You will need
6800this information to recover the steganographic image (e.g. display -size
6801320x256+35 stegano:image.png).</p>
6802
6803<div style="margin: auto;">
6804 <h4><a id="stereo"></a>-stereo <var>+x</var>{<var>+y</var>}</h4>
6805</div>
6806
6807<p class="magick-description">composite two images to create a red / cyan stereo anaglyph.</p>
6808
6809<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>
6810
6811<div style="margin: auto;">
6812 <h4><a id="storage-type"></a>-storage-type <var>type</var></h4>
6813</div>
6814
6815<p class="magick-description">pixel storage type. Here are the valid types:</p>
6816
6817<pre>
6818 char unsigned characters
6819 double doubles
6820 float floats
6821 integer integers
6822 long longs
6823 quantum pixels in the native depth of your ImageMagick distribution
6824 short unsigned shorts
6825</pre>
6826
6827<p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
6828values range from 0 to the maximum value the storage type can support.</p>
6829
6830<div style="margin: auto;">
6831 <h4><a id="stretch"></a>-stretch <var>fontStretch</var></h4>
6832</div>
6833
6834<p class="magick-description">Set a type of stretch style for fonts.</p>
6835
6836<p>This setting suggests a type of stretch that ImageMagick should try to
6837apply to the currently selected font family. Select <var>fontStretch</var> from the following.</p>
6838
6839<pre>
6840 Any
6841 Condensed
6842 Expanded
6843 ExtraCondensed
6844 ExtraExpanded
6845 Normal
6846 SemiCondensed
6847 SemiExpanded
6848 UltraCondensed
6849 UltraExpanded
6850</pre>
6851
6852<p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
6853stretch</a>.</p>
6854
6855<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>
6856
6857<div style="margin: auto;">
6858 <h4><a id="strip"></a>-strip</h4>
6859</div>
6860
6861<p class="magick-description">strip the image of any profiles or comments.</p>
6862
6863<div style="margin: auto;">
6864 <h4><a id="stroke"></a>-stroke <var>color</var></h4>
6865</div>
6866
6867<p class="magick-description">color to use when stroking a graphic primitive.</p>
6868
6869<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6870
6871<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
6872
6873<div style="margin: auto;">
6874 <h4><a id="strokewidth"></a>-strokewidth <var>value</var></h4>
6875</div>
6876
6877<p class="magick-description">set the stroke width.</p>
6878
6879<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
6880
6881<div style="margin: auto;">
6882 <h4><a id="style"></a>-style <var>fontStyle</var></h4>
6883</div>
6884
6885<p class="magick-description">Set a font style for text.</p>
6886
6887<p>This setting suggests a font style that ImageMagick should try to apply to
6888the currently selected font family. Select <var>fontStyle</var> from
6889the following.</p>
6890
6891<pre>
6892 Any
6893 Italic
6894 Normal
6895 Oblique
6896</pre>
6897
6898<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>
6899
6900<div style="margin: auto;">
6901 <h4><a id="subimage-search"></a>-subimage-search</h4>
6902</div>
6903
6904<p class="magick-description">search for subimage.</p>
6905
6906<p>This option is required to have compare search for the best match location
6907of a small image within a larger image. This search will produce two images
6908(or two frames). The first is the "difference" image and the second will
6909be the "match score" image.</p>
6910
6911<p>The "match-score" image is smaller containing a pixel for ever possible
6912position of the top-left corner of the given sub-image. that is its size will
6913be the size of the larger_image - sub_image + 1. The brightest location in
6914this image is the location s the locate on the best match that is also
6915reported. Note that this may or may not be a perfect match, and the actual
6916brightness will reflect this. Other bright 'peaks' can be used to locate other
6917possible matching locations. </p>
6918
6919<p>Note that the search will try to compare the sub-image at every possible
6920location in the larger image, as such it can be very slow. The smaller the
6921sub-image the faster this search is. </p>
6922
6923
6924<div style="margin: auto;">
6925 <h4><a id="swap"></a>-swap <var>index,index</var></h4>
6926</div>
6927
6928<p class="magick-description">Swap the positions of two images in the image sequence.</p>
6929
6930<p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
6931images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
6932the last two images in the sequence.</p>
6933
6934<div style="margin: auto;">
6935 <h4><a id="swirl"></a>-swirl <var>degrees</var></h4>
6936</div>
6937
6938<p class="magick-description">swirl image pixels about the center.</p>
6939
6940<p><var>Degrees</var> defines the tightness of the swirl.</p>
6941
6942<div style="margin: auto;">
6943 <h4><a id="synchronize"></a>-synchronize</h4>
6944</div>
6945
6946<p class="magick-description">synchronize image to storage device.</p>
6947
6948<p>Set to "true" to ensure all image data is fully flushed and synchronized
6949to disk. There is a performance penalty, but the benefits include ensuring a
6950valid image file in the event of a system crash and early reporting if there
6951is not enough disk space for the image pixel cache.</p>
6952
6953<div style="margin: auto;">
6954 <h4><a id="taint"></a>-taint</h4>
6955</div>
6956
6957<p class="magick-description">Mark the image as modified.</p>
6958
6959<div style="margin: auto;">
6960 <h4><a id="text-font"></a>-text-font <var>name</var></h4>
6961</div>
6962
6963<p class="magick-description">font for writing fixed-width text.</p>
6964
6965<p>Specifies the name of the preferred font to use in fixed (typewriter style)
6966formatted text. The default is 14 point <var>Courier</var>.</p>
6967
6968<p>You can tag a font to specify whether it is a PostScript, TrueType, or
6969OPTION1 font. For example, <code>Courier.ttf</code> is a TrueType font and
6970<code>x:fixed</code> is OPTION1.</p>
6971
6972<div style="margin: auto;">
6973 <h4><a id="texture"></a>-texture <var>filename</var></h4>
6974</div>
6975
6976<p class="magick-description">name of texture to tile onto the image background.</p>
6977
6978<div style="margin: auto;">
6979 <h4><a id="threshold"></a>-threshold <var>value</var>{<var>%</var>}</h4>
6980</div>
6981
6982<!-- {<var>green,blue,opacity</var>}
6983<p>If the green or blue value is omitted, these channels use the same value as
6984the first one provided. If all three color values are the same, the result is
6985a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
6986and any partially transparent pixel becomes fully transparent.</p>
6987-->
6988
6989<p class="magick-description">Apply simultaneous black/white threshold to the image.</p>
6990
6991<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
6992maximum channel value, while all other values are assigned the minimum.</p>
6993
6994<p> The threshold value can be given as a percentage or as an absolute integer
6995value corresponding to the desired channel value. When given as an integer,
6996the minimum attainable value is 0 (corresponding to black when all channels
6997are affected), but the maximum value (corresponding to white) is that of the
6998<code>quantum depth</code> of the particular build of ImageMagick, and is
6999therefore dependent on the installation. For that reason, a reasonable
7000recommendation for most applications is to specify the threshold values as
7001a percentage. </p>
7002
7003<p> The following would force pixels with red values above 50% to have 100%
7004red values, while those at or below 50% red would be set to 0 in the red
7005channel. The green, blue, and alpha channels (if present) would be unchanged.
7006</p>
7007
7008<pre>
7009convert in.png -channel red -threshold 50% out.png
7010</pre>
7011
7012<p>As (possibly) impractical but instructive examples, the following would
7013generate an all-black and an all-white image with the same dimensions as the
7014input image.</p>
7015
7016
7017<pre>
7018convert in.png -threshold 100% black.png
7019convert in.png -threshold -1 white.png
7020</pre>
7021
7022<p>Note that the values of the transparency channel is treated as 'matte'
7023values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
7024
7025<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>.
7026</p>
7027
7028<div style="margin: auto;">
7029 <h4><a id="thumbnail"></a>-thumbnail <var>geometry</var></h4>
7030</div>
7031
7032<p class="magick-description">Create a thumbnail of the image.</p>
7033
7034<p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
7035for speed and any image profile, other than a color profile, is removed to
7036reduce 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>
7037
7038<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7039
7040<div style="margin: auto;">
7041 <h4><a id="tile"></a>-tile <var>filename</var></h4>
7042</div>
7043
7044<p class="magick-description">Set the tile image used for filling a subsequent graphic primitive.</p>
7045
7046<div style="margin: auto;">
7047 <h4>-tile <var>geometry</var></h4>
7048</div>
7049
7050<p class="magick-description">Specify the layout of images.</p>
7051
7052<p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
7053
7054<div style="margin: auto;">
7055 <h4>-tile</h4>
7056</div>
7057
7058<p class="magick-description">Specifies that a subsequent composite operation is repeated across and down image.</p>
7059
7060<div style="margin: auto;">
7061 <h4><a id="tile-offset"></a>-tile-offset {<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var></h4>
7062</div>
7063
7064<p class="magick-description">Specify the offset for tile images, relative to the background image it is tiled on.</p>
7065
7066<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
7067creating a tiled canvas using <code>TILE:</code> or <code>PATTERN:</code> input
7068formats. </p>
7069
7070<p>Internally ImageMagick does a <a href="command-line-options.html#roll">-roll</a> of the tile image
7071by the arguments given when the tile image is set. </p>
7072
7073<div style="margin: auto;">
7074 <h4><a id="tint"></a>-tint <var>value</var></h4>
7075</div>
7076
7077<p class="magick-description">Tint the image with the fill color.</p>
7078
7079<p>Tint the image with the fill color.</p>
7080
7081<p>Specify the amount of tinting as a percentage. Pure colors like black,
7082white red, yellow, will not be affected by -tint. Only mid-range colors such
7083as the various shades of grey.</p>
7084
7085<div style="margin: auto;">
7086 <h4><a id="title"></a>-title <var>string</var></h4>
7087</div>
7088
7089<p class="magick-description">Assign a title to displayed image.", "animate", "display", "montage</p>
7090
7091<p>Use this option to assign a specific title to the image. This assigned to
7092the image window and is typically displayed in the window title bar.
7093Optionally you can include the image filename, type, width, height, Exif data,
7094or other image attribute by embedding special format characters described
7095under the <a href="command-line-options.html#format">-format</a> option.</p>
7096
7097<p>For example,</p>
7098
7099<p class="crtsnip">
7100 -title "%m:%f %wx%h"
7101</p>
7102
7103<p>produces an image title of <code>MIFF:bird.miff 512x480</code> for an image
7104titled <code>bird.miff</code> and whose width is 512 and height is 480.</p>
7105
7106
7107<div style="margin: auto;">
7108 <h4><a id="transform"></a>-transform</h4>
7109</div>
7110
7111<p class="magick-description">transform the image.</p>
7112
7113<p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
7114
7115<pre>
7116convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg
7117</pre>
7118
7119
7120<p>This operator has been now been superseded by the <a href="command-line-options.html#distort">-distort</a> '<code>AffineProjection</code>' method. </p>
7121
7122
7123<div style="margin: auto;">
7124 <h4><a id="transparent"></a>-transparent <var>color</var></h4>
7125</div>
7126
7127<p class="magick-description">Make this color transparent within the image.</p>
7128
7129<p>The <var>color</var> argument is defined using the format
7130described 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
7131given. </p>
7132
7133<p>Use <a href="command-line-options.html#transparent">+transparent</a> to invert the pixels matched.
7134that is make all non-matching colors transparent. </p>
7135
7136<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
7137current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
7138However the <a href="command-line-options.html#transparent">-transparent</a> operator also ensures
7139that 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>
7140
7141<p>Note that this does not define the color as being the 'transparency color'
7142used for color-mapped image formats, such as GIF. For that use <a href="command-line-options.html#transparent-color">-transparent-color</a> </p>
7143
7144
7145<div style="margin: auto;">
7146 <h4><a id="transparent-color"></a>-transparent-color <var>color</var></h4>
7147</div>
7148
7149<p class="magick-description">Set the transparent color.</p>
7150
7151<p>Sometimes this is used for saving to image formats such as
7152GIF and PNG8 which uses this color to represent boolean transparency. This
7153does not make a color transparent, it only defines what color the transparent
7154color 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>
7155
7156<p>This option allows you to have both an opaque visible color, as well as a
7157transparent color of the same color value without conflict. That is, you can
7158use the same color for both the transparent and opaque color areas within an
7159image. This, in turn, frees to you to select a transparent color that is
7160appropriate when an image is displayed by an application that does not handle a
7161transparent color index, while allowing ImageMagick to correctly handle images of this
7162type. </p>
7163
7164<p>The default transparent color is <code>#00000000</code>, which is fully transparent black.</p>
7165
7166<div style="margin: auto;">
7167 <h4><a id="transpose"></a>-transpose</h4>
7168</div>
7169
7170<p class="magick-description">Mirror the image along the top-left to bottom-right diagonal.</p>
7171
7172<p> This option mathematically transposes the pixel array. It is equivalent to the sequence <code>-flip -rotate 90</code>.
7173</p>
7174
7175<div style="margin: auto;">
7176 <h4><a id="transverse"></a>-transverse</h4>
7177</div>
7178
7179<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>
7180
7181
7182<div style="margin: auto;">
7183 <h4><a id="treedepth"></a>-treedepth <var>value</var></h4>
7184</div>
7185
7186<p class="magick-description">tree depth for the color reduction algorithm.</p>
7187
7188<p>Normally, this integer value is zero or one. A value of zero or one causes
7189the use of an optimal tree depth for the color reduction algorithm.</p>
7190
7191<p>An optimal depth generally allows the best representation of the source
7192image with the fastest computational speed and the least amount of memory.
7193However, the default depth is inappropriate for some images. To assure the
7194best representation, try values between 2 and 8 for this parameter. Refer to
7195the <a href="quantize.html">color reduction algorithm</a> for more details.</p>
7196
7197<p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
7198option, or writing to an image format which requires color reduction, is
7199required for this option to take effect.</p>
7200
7201<div style="margin: auto;">
7202 <h4><a id="trim"></a>-trim</h4>
7203</div>
7204
7205<p class="magick-description">trim an image.</p>
7206
7207<p>This option removes any edges that are exactly the same color as the corner
7208pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
7209edges that are nearly the same color as the corner pixels.</p>
7210
7211<p>The page or virtual canvas information of the image is preserved allowing
7212you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
7213image. Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
7214information if it is unwanted.</p>
7215
7216<p>If the trimmed image 'disappears' an warning is produced, and a special
7217single pixel transparent 'missed' image is returned, in the same way as when a
7218<a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
7219
7220
7221<div style="margin: auto;">
7222 <h4><a id="type"></a>-type <var>type</var></h4>
7223</div>
7224
7225<p class="magick-description">the image type.</p> <p>Choose from: <code>Bilevel</code>,
7226<code>Grayscale</code>, <code>GrayscaleMatte</code>, <code>Palette</code>,
7227<code>PaletteMatte</code>, <code>TrueColor</code>, <code>TrueColorMatte</code>,
7228<code>ColorSeparation</code>, or <code>ColorSeparationMatte</code>.</p>
7229
7230<p>Normally, when a format supports different subformats such as grayscale and
7231truecolor, 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
7232example, to prevent a JPEG from being written in grayscale format even though
7233only gray pixels are present, use.</p>
7234
7235<pre>
7236convert bird.png -type TrueColor bird.jpg
7237</pre>
7238
7239<p>Similarly, use <a href="command-line-options.html#type">-type TrueColorMatte</a> to force the
7240encoder to write an alpha channel even though the image is opaque, if the
7241output format supports transparency.</p>
7242
7243<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>
7244
7245<div style="margin: auto;">
7246 <h4><a id="undercolor"></a>-undercolor <var>color</var></h4>
7247</div>
7248
7249<p class="magick-description">set the color of the annotation bounding box.</p>
7250
7251<p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
7252
7253<p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
7254
7255
7256<div style="margin: auto;">
7257 <h4><a id="update"></a>-update <var>seconds</var></h4>
7258</div>
7259
7260<p class="magick-description">detect when image file is modified and redisplay.</p>
7261
7262<p>Suppose that while you are displaying an image the file that is currently
7263displayed is over-written. <code>display</code> will automagically detect that
7264the input file has been changed and update the displayed image
7265accordingly.</p>
7266
7267
7268<div style="margin: auto;">
7269 <h4><a id="unique-colors"></a>-unique-colors</h4>
7270</div>
7271
7272<p class="magick-description">discard all but one of any pixel color.</p>
7273
7274
7275<div style="margin: auto;">
7276 <h4><a id="units"></a>-units <var>type</var></h4>
7277</div>
7278
7279<p class="magick-description">the units of image resolution.</p>
7280
7281<p>Choose from: <code>Undefined</code>, <code>PixelsPerInch</code>, or
7282<code>PixelsPerCentimeter</code>. This option is normally used in conjunction
7283with the <a href="command-line-options.html#density">-density</a> option.</p>
7284
7285
7286<div style="margin: auto;">
7287 <h4><a id="unsharp"></a>-unsharp <var>radius</var><br>-unsharp <var>radius</var>x<var>sigma</var>{<var>+gain</var>}{<var>+threshold</var>}</h4>
7288</div>
7289
7290<p class="magick-description">sharpen the image with an unsharp mask operator.</p>
7291
7292<p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
7293convolved with a Gaussian operator of the given radius and standard deviation
7294(sigma). For reasonable results, radius should be larger than sigma. Use
7295a radius of 0 to have the method select a suitable radius.</p>
7296
7297<p>The parameters are:</p>
7298
7299<pre>
7300 radius The radius of the Gaussian, in pixels, not counting the center
7301 pixel (default 0).
7302 sigma The standard deviation of the Gaussian, in pixels (default 1.0).
7303 gain The fraction of the difference between the original and the blur
7304 image that is added back into the original (default 1.0).
7305 threshold The threshold, as a fraction of <var>QuantumRange</var>, needed to apply the
7306 difference amount (default 0.05).
7307</pre>
7308
7309
7310<div style="margin: auto;">
7311 <h4><a id="verbose"></a>-verbose</h4>
7312</div>
7313
7314<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>
7315
7316
7317<div style="margin: auto;">
7318 <h4><a id="version"></a>-version</h4>
7319</div>
7320
7321<p class="magick-description">print ImageMagick version string and exit.</p>
7322
7323
7324<div style="margin: auto;">
7325 <h4><a id="view"></a>-view <var>string</var></h4>
7326</div>
7327
7328<p class="magick-description">FlashPix viewing parameters.</p>
7329
7330
7331<div style="margin: auto;">
7332 <h4><a id="vignette"></a>-vignette <var>radius</var>{x<var>sigma</var>}{<var>+-</var>}<var>x</var>{<var>+-</var>}<var>y</var>{<var>%</var>}</h4>
7333</div>
7334
7335<p class="magick-description">soften the edges of the image in vignette style.</p>
7336
7337<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>
7338
7339<div style="margin: auto;">
7340 <h4><a id="virtual-pixel"></a>-virtual-pixel <var>method</var></h4>
7341</div>
7342
7343<p class="magick-description">Specify contents of <var>virtual pixels</var>.</p>
7344
7345<p>This option defines what color source should be used if and when a color
7346lookup completely 'misses' the source image. The color(s) that appear to
7347surround the source image. Generally this color is derived from the source
7348image, but could also be set to a specify background color. </p>
7349
7350<p>Choose from these methods:</p>
7351
7352<pre>
7353 background the area surrounding the image is the background color
7354 black the area surrounding the image is black
7355 checker-tile alternate squares with image and background color
7356 dither non-random 32x32 dithered pattern
7357 edge extend the edge pixel toward infinity
7358 gray the area surrounding the image is gray
7359 horizontal-tile horizontally tile the image, background color above/below
7360 horizontal-tile-edge horizontally tile the image and replicate the side edge pixels
7361 mirror mirror tile the image
7362 random choose a random pixel from the image
7363 tile tile the image (default)
7364 transparent the area surrounding the image is transparent blackness
7365 vertical-tile vertically tile the image, sides are background color
7366 vertical-tile-edge vertically tile the image and replicate the side edge pixels
7367 white the area surrounding the image is white
7368</pre>
7369
7370<p>The default value is "edge".</p>
7371
7372<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>.
7373However it also effects operations that may access pixels just outside the
7374image 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>
7375
7376<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>
7377
7378
7379<div style="margin: auto;">
7380 <h4><a id="visual"></a>-visual <var>type</var></h4>
7381</div>
7382
7383<p class="magick-description">Animate images using this X visual type.", 'animate', 'display'</p>
7384
7385<p>Choose from these visual classes:</p>
7386
7387<pre>
7388 StaticGray
7389 GrayScale
7390 StaticColor
7391 PseudoColor
7392 TrueColor
7393 DirectColor
7394 default
7395 visual id
7396</pre>
7397
7398<p>The X server must support the visual you choose, otherwise an error occurs.
7399If a visual is not specified, the visual class that can display the most
7400simultaneous colors on the default screen is chosen.</p>
7401
7402
7403<div style="margin: auto;">
7404 <h4><a id="watermark"></a>-watermark <var>brightness</var>x<var>saturation</var></h4>
7405</div>
7406
7407<p class="magick-description">Watermark an image using the given percentages of brightness and saturation.</p>
7408
7409<p>Take a grayscale image (with alpha mask) and modify the destination image's
7410brightness according to watermark image's grayscale value and the
7411<var>brightness</var> percentage. The destinations color saturation
7412attribute is just direct modified by the <var>saturation</var>
7413percentage, which defaults to 100 percent (no color change). </p>
7414
7415
7416<div style="margin: auto;">
7417 <h4><a id="wave"></a>-wave <var>amplitude</var><br>-wave <var>amplitude</var>x<var>wavelength</var></h4>
7418</div>
7419
7420<p class="magick-description">Shear the columns of an image into a sine wave.</p>
7421
7422<p>Specify <var>amplitude</var> and <var>wavelength</var>
7423of the wave.</p>
7424
7425<div style="margin: auto;">
7426 <h4><a id="weight"></a>-weight <var>fontWeight</var></h4>
7427</div>
7428
7429<p class="magick-description">Set a font weight for text.</p>
7430
7431<p>This setting suggests a font weight that ImageMagick should try to apply to
7432the currently selected font family. Use a positive integer for
7433<var>fontWeight</var> or select from the following.</p>
7434
7435<table class="table table-condensed table-striped">
7436 <col width="25%">
7437 <col width="75%">
7438 <thead>
7439 <tr>
7440 <th><var>fontWeight</var></th>
7441 <th>Description</th>
7442 </tr>
7443 </thead>
7444 <tbody>
7445 <tr><td>All </td>
7446 <td>No effect. </td></tr>
7447 <tr><td>Bold </td>
7448 <td>Same as <var>fontWeight</var> = 700.</td></tr>
7449 <tr><td>Bolder </td>
7450 <td>Add 100 to font weight if currently ≤ 800.</td></tr>
7451 <tr><td>Lighter </td>
7452 <td>Subtract 100 to font weight if currently ≤ 100.</td></tr>
7453 <tr><td>Normal </td>
7454 <td>Same as <var>fontWeight</var> = 400.</td></tr>
7455 </tbody>
7456 </table>
7457
7458<p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list
7459weight</a>.</p>
7460
7461<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>
7462
7463<div style="margin: auto;">
7464 <h4><a id="white-point"></a>-white-point <var>x,y</var></h4>
7465</div>
7466
7467<p class="magick-description">chromaticity white point.</p>
7468
7469<div style="margin: auto;">
7470 <h4><a id="white-threshold"></a>-white-threshold <var>value</var>{<var>%</var>}</h4>
7471</div>
7472
7473<p class="magick-description">Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged.</p>
7474
7475<p> The threshold value can be given as a percentage or as an absolute integer
7476value within [0, <var>QuantumRange</var>] corresponding to the
7477desired <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>
7478
7479<div style="margin: auto;">
7480 <h4><a id="window"></a>-window <var>id</var></h4>
7481</div>
7482
7483<p class="magick-description">Make the image the background of a window.", 'animate', 'display'</p>
7484
7485<p><var>id</var> can be a window id or name. Specify <code>root</code>
7486to select X's root window as the target window.</p>
7487
7488<p>By default the image is tiled onto the background of the target window. If
7489<code>backdrop</code> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
7490image is surrounded by the background color. Refer to <code>X RESOURCES</code>
7491for details.</p>
7492
7493<p>The image will not display on the root window if the image has more unique
7494colors than the target window colormap allows. Use <a href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
7495
7496<div style="margin: auto;">
7497 <h4><a id="window-group"></a>-window-group</h4>
7498</div>
7499
7500<p class="magick-description">specify the window group.</p>
7501
7502<div style="margin: auto;">
7503 <h4><a id="write"></a>-write <var>filename</var></h4>
7504</div>
7505
7506<p class="magick-description">write an image sequence.</p>
7507
7508<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>
7509
7510<p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
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