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243 <h1>Create, Edit, or Compose Bitmap Images With These Command-line Options</h1>
244 <p class="navigation-index">
245 [ <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#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#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#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 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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#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#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#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#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#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#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#pen">‑pen</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#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#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>
247 <div class="doc-section">
249 <p>Below is list of command-line options recognized by the ImageMagick <a
250 href="command-line-tools.html">command-line
251 tools</a>. If you want a description of a particular option, click on the
252 option name in the navigation bar above and you will go right to it. Unless
253 otherwise noted, each option is recognized by the commands <a href="convert.html">convert</a>, <a href="mogrify.html">mogrify</a>.</p>
255 <div style="margin: auto;">
256 <h4><a id="adaptive-blur"></a>-adaptive-blur <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4>
259 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adaptively blur pixels, with decreasing effect near edges.</td><td style='text-align:right;'></td></tr></table>
261 <p>A Gaussian operator of the given radius and standard deviation (<em
262 class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it
265 <div style="margin: auto;">
266 <h4><a id="adaptive-resize"></a>-adaptive-resize <em class="arg">geometry</em></h4>
269 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resize the image using data-dependent triangulation.</td><td style='text-align:right;'></td></tr></table>
271 <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>
272 option defaults to data-dependent triangulation. Use the <a
273 href="command-line-options.html#filter">-filter</a> to choose a different resampling algorithm.
274 Offsets, if present in the geometry string, are ignored, and the <a
275 href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
277 <div style="margin: auto;">
278 <h4><a id="adaptive-sharpen"></a>-adaptive-sharpen <em class="arg">radius</em>[x<em class="arg">sigma</em>]</h4>
281 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adaptively sharpen pixels, with increasing effect near edges.</td><td style='text-align:right;'></td></tr></table>
283 <p>A Gaussian operator of the given radius and standard deviation (<em
284 class="arg">sigma</em>) is used. If <em class="arg">sigma</em> is not given it
287 <div style="margin: auto;">
288 <h4><a id="adjoin"></a>-adjoin</h4>
291 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Join images into a single multi-image file.</td><td style='text-align:right;'></td></tr></table>
293 <p>This option is enabled by default. An attempt is made to save all images of
294 an image sequence into the given output file. However, some formats, such as
295 JPEG and PNG, do not support more than one image per file, and in that case
296 ImageMagick is forced to write each image as a separate file. As such, if
297 more than one image needs to be written, the filename given is modified by
298 adding a <a href="command-line-options.html#scene">-scene</a> number before the suffix, in order to
299 make distinct names for each image. </p>
301 <p>Use <a href="command-line-options.html#adjoin">+adjoin</a> to force each image to be written to
302 separate files, whether or not the file format allows multiple images per file
303 (for example, GIF, MIFF, and TIFF). </p>
305 <p>Including a C-style integer format string in the output filename will
306 automagically enable <a href="command-line-options.html#adjoin">+adjoin</a> and are used to specify
307 where the <a href="command-line-options.html#scene">-scene</a> number is placed in the filenames. These
308 strings, such as '<kbd>%d</kbd>' or '<kbd>%03d</kbd>', are familiar to those
309 who have used the standard <kbd>printf()</kbd>' C-library function. As an
310 example, the command</p>
312 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: rose: -morph 15 my%02dmorph.jpg</span></p>
313 <p>will create a sequence of 17 images (the two given plus 15 more created by
314 <a href="command-line-options.html#morph">-morph</a>), named: my00morph.jpg, my01morph.jpg,
315 my02morph.jpg, ..., my16morph.jpg. </p>
317 <p>In summary, ImageMagick tries to write all images to one file, but will
318 save to multiple files, if any of the following conditions exist...
320 <li>the output image's file format does not allow multi-image files,
321 <li>the <a href="command-line-options.html#adjoin">+adjoin</a> option is given, or
322 <li>a printf() integer format string (eg: "%d") is present in the output
327 <div style="margin: auto;">
328 <h4><a id="affine"></a>-affine
329 <em class="arg">s<sub>x</sub></em>,<em class="arg">r<sub>x</sub></em>,<em
330 class="arg">r<sub>y</sub></em>,<em class="arg">s<sub>y</sub></em>[,<em
331 class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em>]</h4>
334 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the drawing transformation matrix for combined rotating and scaling.</td><td style='text-align:right;'></td></tr></table>
336 <p>This option sets a transformation matrix, for use by subsequent <a
337 href="command-line-options.html#draw">-draw</a> or <a href="command-line-options.html#transform">-transform</a> options. </p>
339 <p>The matrix entries are entered as comma-separated numeric values either in
340 quotes or without spaces. </p>
342 <p>Internally, the transformation matrix has 3x3 elements, but three of them
343 are omitted from the input because they are constant. The new (transformed)
344 coordinates (<em class="arg">x'</em>, <em class="arg">y'</em>) of a pixel at
345 position (<em class="arg">x</em>, <em class="arg">y</em>) in the original
346 image are calculated using the following matrix equation.</p>
349 <img alt="affine transformation" src="../images/affine.png"/>
352 <p> The size of the resulting image is that of the smallest rectangle that
353 contains the transformed source image. The parameters <em
354 class="arg">t<sub>x</sub></em> and <em class="arg">t<sub>y</sub></em>
355 subsequently shift the image pixels so that those that are moved out of the
356 image area are cut off.</p>
358 <p>The transformation matrix complies with the left-handed pixel coordinate
359 system: positive <em class="arg">x</em> and <em class="arg">y</em> directions
360 are rightward and downward, resp.; positive rotation is clockwise.</p>
362 <p> If the translation coefficients <em class="arg">t<sub>x</sub></em> and <em
363 class="arg">t<sub>y</sub></em> are omitted they default to 0,0. Therefore,
364 four parameters suffice for rotation and scaling without translation.</p>
366 <p>Scaling by the factors <em class="arg">s<sub>x</sub></em> and <em
367 class="arg">s<sub>y</sub></em> in the <em>x</em> and <em>y</em> directions,
368 respectively, is accomplished with the following.</p>
370 <p>See <a href="command-line-options.html#transform">-transform</a>, and the <a
371 href="command-line-options.html#distort">-distort</a> method '<kbd>Affineprojection</kbd> for more
375 <p class="crtsnip"> -affine <em class="arg">s<sub>x</sub></em>,0,0,<em
376 class="arg">s<sub>y</sub></em> </p>
378 <p>Translation by a displacement (<em class="arg">t<sub>x</sub></em>, <em
379 class="arg">t<sub>y</sub></em>) is accomplished like so:</p>
382 -affine 1,0,0,1,<em class="arg">t<sub>x</sub></em>,<em class="arg">t<sub>y</sub></em>
385 <p>Rotate clockwise about the origin (the upper left-hand corner) by an angle
386 <em>a</em> by letting <em>c</em> = cos(<em>a</em>), <em>s</em>
387 = sin(<em>a</em>), and using the following.</p>
390 -affine <em>c</em>,<em>s</em>,-<em>s</em>,<em>c</em>
393 <p>The cumulative effect of a sequence of <a href="command-line-options.html#affine" >-affine</a>
394 transformations can be accomplished by instead by a single <a href="command-line-options.html#affine"
395 >-affine</a> operation using the matrix equal to the product of the matrices
396 of the individual transformations.</p>
398 <p>An attempt is made to detect near-singular transformation matrices. If the
399 matrix determinant has a sufficiently small absolute value it is rejected.</p>
401 <div style="margin: auto;">
402 <h4><a id="alpha"></a>-alpha <em class="arg">type</em></h4>
405 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Gives control of the alpha/matte channel of an image.</td><td style='text-align:right;'></td></tr></table>
407 <p>Used to set a flag on an image indicating whether or not to use existing alpha
408 channel data, to create an alpha channel, or to perform other operations on the alpha channel. Choose the argument <em class="arg">type</em> from the list below.</p>
414 <th align="left" style="width: 8%">type</th>
415 <th align="left">Description</th>
419 <td valign="top"><kbd>Activate</kbd> or <kbd>On</kbd></td>
421 Enable the image's transparency channel. Note normally <kbd>Set</kbd>
422 should be used instead of this, unless you specifically need to
423 preserve existing (but specifically turned <kbd>Off</kbd>) transparency
427 <td valign="top"><kbd>Deactivate</kbd> or <kbd>Off</kbd></td>
429 Disables the image's transparency channel. Does not delete or change the
430 existing data, just turns off the use of that data.</td></tr>
433 <td valign="top"><kbd>Set</kbd></td>
435 Activates the alpha/matte channel. If it was previously turned off
436 then it also resets the channel to opaque. If the image already had
437 the alpha channel turned on, it will have no effect.</td></tr>
440 <td valign="top"><kbd>Opaque</kbd></td>
442 Enables the alpha/matte channel and forces it to be fully opaque.
446 <td valign="top"><kbd>Transparent</kbd></td>
448 Activates the alpha/matte channel and forces it to be fully
449 transparent. This effectively creates a fully transparent image the
450 same size as the original and with all its original RGB data still
451 intact, but fully transparent. </td></tr>
454 <td valign="top"><kbd>Extract</kbd></td>
456 Copies the alpha channel values into all the color channels and turns
457 '<kbd>Off</kbd>' the the image's transparency, so as to generate
458 a gray-scale mask of the image's shape. The alpha channel data is left
459 intact just deactivated. This is the inverse of '<kbd>Copy</kbd>'.
463 <td valign="top"><kbd>Copy</kbd></td>
465 Turns '<kbd>On</kbd>' the alpha/matte channel, then copies the
466 gray-scale intensity of the image, into the alpha channel, converting
467 a gray-scale mask into a transparent shaped mask ready to be colored
468 appropriately. The color channels are not modified. </td></tr>
471 <td valign="top"><kbd>Shape</kbd></td>
473 As per '<kbd>Copy</kbd>' but also colors the resulting shape mask with
474 the current background color. That is the RGB color channels is
475 replaced, with appropriate alpha shape.
479 <td valign="top"><kbd>Remove</kbd></td>
481 Composite the image over the background color.
485 <td valign="top"><kbd>Background</kbd></td>
487 Set any fully-transparent pixel to the background color, while leaving
488 it fully-transparent. This can make some image file formats, such as
489 PNG, smaller as the RGB values of transparent pixels are more uniform,
490 and thus can compress better.
495 <p>Note that while the <a href="command-line-options.html#matte" >+matte</a> operation is the same as
496 "<kbd><a href="command-line-options.html#alpha" >-alpha</a> Off</kbd>", the <a href="command-line-options.html#matte"
497 >-matte</a> operation is the same as "<kbd><a href="command-line-options.html#alpha" >-alpha</a>
498 Set</kbd>" and not "<kbd><a href="command-line-options.html#alpha" >-alpha</a> On</kbd>". </p>
501 <div style="margin: auto;">
502 <h4><a id="annotate"></a>
503 -annotate <em class="arg">degrees</em> <em class="arg">text</em><br />
504 -annotate <em class="arg">Xdegrees</em>x<em class="arg">Ydegrees</em> <em
505 class="arg">text</em><br /> -annotate <em class="arg">Xdegrees</em>x<em
506 class="arg">Ydegrees</em> {+-}<em class="arg">t<sub>x</sub></em>{+-}<em
507 class="arg">t<sub>y</sub></em> <em class="arg">text</em></h4>
510 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Annotate an image with text.</td><td style='text-align:right;'></td></tr></table>
512 <p>This is a convenience for annotating an image with text. For more precise
513 control over text annotations, use <a href="command-line-options.html#draw">-draw</a>.</p>
516 <p>The values <em class="arg">Xdegrees</em> and <em class="arg">Ydegrees</em>
517 control the shears with respect to the , respectively, applied to the text,
518 while <em class="arg">t<sub>x</sub></em> and <em
519 class="arg">t<sub>y</sub></em> are offsets that give the location of the text
520 relative to the upper left corner of the image.</p>
522 <p>Using <a href="command-line-options.html#annotate">-annotate</a> <em class="arg">degrees</em>
523 or <a href="command-line-options.html#annotate">-annotate</a> <em class="arg">degrees</em>x<em
524 class="arg">degrees</em> produces an unsheared rotation of the text. The
525 direction of the rotation is positive, which means a clockwise rotation if <em
526 class="arg">degrees</em> is positive. (This conforms to the usual mathematical
527 convention once it is realized that the positive <em>y</em>–direction is
528 conventionally considered to be <em>downward</em> for images.)</p>
530 <p>The new (transformed) coordinates (<em class="arg">x'</em>, <em
531 class="arg">y'</em>) of a pixel at position (<em class="arg">x</em>, <em
532 class="arg">y</em>) in the image are calculated using the following matrix
533 equation.</p> <div class="eqn"><img alt="annotate transformation" src="../images/annotate.png"/></div>
535 <p>If <em class="arg">t<sub>x</sub></em> and <em
536 class="arg">t<sub>y</sub></em> are omitted, they default to 0. This makes the
537 bottom-left of the text becomes the upper-left corner of the image, which is
538 probably undesirable. Adding a <a href="command-line-options.html#gravity" >-gravity</a> option in this
539 case leads to nice results.</p>
541 <p>Text is any UTF-8 encoded character sequence. If <em class="arg">text</em>
542 is of the form '@mytext.txt', the text is read from the file
543 <kbd>mytext.txt</kbd>. Text in a file is taken literally; no embedded
544 formatting characters are recognized.</p>
546 <div style="margin: auto;">
547 <h4><a id="antialias"></a>-antialias</h4>
550 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Enable/Disable of the rendering of anti-aliasing pixels when
551 drawing fonts and lines.</td><td style='text-align:right;'></td></tr></table>
553 <p>By default, objects (e.g. text, lines, polygons, etc.) are antialiased when
554 drawn. Use <a href="command-line-options.html#antialias">+antialias</a> to disable the addition of
555 antialiasing edge pixels. This will then reduce the number of colors added to
556 an image to just the colors being directly drawn. That is, no mixed colors
557 are added when drawing such objects. </p>
559 <div style="margin: auto;">
560 <h4><a id="append"></a>-append</h4>
563 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Join current images vertically or horizontally.</td><td style='text-align:right;'></td></tr></table>
565 <p>This option creates a single longer image image, by joining all the current
566 images in sequence top-to-bottom. Use <a href="command-line-options.html#append">+append</a> to
567 stack images left-to-right. </p>
569 <p>If they are not of the same width, narrower images are padded with the
570 current <a href="command-line-options.html#background">-background</a> color setting, and their
571 position relative to each other can be controlled by the current <a
572 href="command-line-options.html#gravity">-gravity</a> setting. </p>
575 <div style="margin: auto;">
576 <h4><a id="attenuate"></a>-attenuate <em class="arg">value</em></h4>
579 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Lessen (or intensify) when adding noise to an image.</td><td style='text-align:right;'></td></tr></table>
581 <p>If unset the value is equivelent to 1.0, or a maximum noise addition</p>
583 <div style="margin: auto;">
584 <h4><a id="authenticate"></a>-authenticate <em class="arg">password</em></h4>
587 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Decrypt a PDF with a password.</td><td style='text-align:right;'></td></tr></table>
589 <p>Use this option to supply a <em class="arg">password</em> for decrypting
590 a PDF that has been encrypted using Microsoft Crypto API (MSC API). The
591 encrypting using the MSC API is not supported.</p>
593 <p>For a different encryption method, see <a href="command-line-options.html#encipher">-encipher</a>
594 and <a href="command-line-options.html#decipher">-decipher</a>. </p>
598 <div style="margin: auto;">
599 <h4><a id="auto-gamma"></a>-auto-gamma</h4>
602 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically adjust gamma level of image.</td><td style='text-align:right;'></td></tr></table>
604 <p>This calculates the mean values of an image, then applies a calculated <a
605 href="command-line-options.html#gamma" >-gamma</a> adjustment so that is the mean color exists in the
606 image it will get a have a value of 50%. </p>
608 <p>This means that any solid 'gray' image becomes 50% gray. </p>
610 <p>This works well for real-life images with little or no extreme dark and
611 light areas, but tend to fail for images with large amounts of bright sky or
612 dark shadows. It also does not work well for diagrams or cartoon like images.
615 <p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
616 '<em>sync</em>' flag for channel synchronization), to determine which color
617 values is used and modified. As the default <a href="command-line-options.html#channel"
618 >-channel</a> setting is '<em>RGB,sync</em>', channels are modified
619 together by the same gamma value, preserving colors. </p>
623 <div style="margin: auto;">
624 <h4><a id="auto-level"></a>-auto-level</h4>
627 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically adjust color levels of image.</td><td style='text-align:right;'></td></tr></table>
629 <p>This is a 'perfect' image normalization operator. It finds the exact
630 minimum and maximum color values in the image and then applies a <a
631 href="command-line-options.html#level" >-level</a> operator to stretch the values to the full range of
634 <p>The operator is not typically used for real-life images, image scans, or
635 JPEG format images, as a single 'out-rider' pixel can set a bad min/max values
636 for the <a href="command-line-options.html#level" >-level</a> operation. On the other hand it is the
637 right operator to use for color stretching gradient images being used to
638 generate Color lookup tables, distortion maps, or other 'mathematically'
641 <p>The operator is very similar to the <a href="command-line-options.html#normalize">-normalize</a>, <a
642 href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>, and <a href="command-line-options.html#linear-stretch"
643 >-linear-stretch</a> operators, but without 'histogram binning' or 'clipping'
644 problems that these operators may have. That is <a href="command-line-options.html#auto-level"
645 >-auto-level</a> is the perfect or ideal version these operators. </p>
647 <p>It uses the <a href="command-line-options.html#channel" >-channel</a> setting, (including the
648 special '<em>sync</em>' flag for channel synchronization), to determine
649 which color values are used and modified. As the default <a
650 href="command-line-options.html#channel" >+channel</a> setting is '<em>RGB,sync</em>', the
651 '<em>sync</em>' ensures that the color channels will are modified
652 together by the same gamma value, preserving colors, and ignoring
656 <div style="margin: auto;">
657 <h4><a id="auto-orient"></a>-auto-orient</h4>
660 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Automagically orient (rotate) an image created by a digital camera.</td><td style='text-align:right;'></td></tr></table>
662 <p>This operator reads and resets the EXIF image profile setting 'Orientation'
663 and then performs the appropriate 90 degree rotation on the image to orient
664 the image, for correct viewing. </p>
666 <p>This EXIF profile setting is usually set using a gravity sensor in digital
667 camera, however photos taken directly downward or upward may not have an
668 appropriate value. Also images that have been orientation 'corrected' without
669 reseting this setting, may be 'corrected' again resulting in a incorrect
670 result. If the EXIF profile was previously stripped, the <a
671 href="command-line-options.html#auto-orient" >-auto-orient</a> operator will do nothing. </p>
674 <div style="margin: auto;">
675 <h4><a id="average"></a>-average</h4>
678 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Average a set of images.</td><td style='text-align:right;'></td></tr></table>
680 <p>An error results if the images are not identically sized.</p>
683 <div style="margin: auto;">
684 <h4><a id="backdrop"></a>-backdrop</h4>
687 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Display the image centered on a backdrop.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
689 <p>This backdrop covers the entire workstation screen and is useful for hiding
690 other X window activity while viewing the image. The color of the backdrop is
691 specified as the background color. The color is specified using the format
692 described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
694 <div style="margin: auto;">
695 <h4><a id="background"></a>-background <em class="arg">color</em></h4>
698 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the background color.</td><td style='text-align:right;'></td></tr></table>
700 <p>The color is specified using the format described under the <a
701 href="command-line-options.html#fill">-fill</a> option. The default background color (if none is
702 specified or found in the image) is white.</p>
704 <div style="margin: auto;">
705 <h4><a id="bench"></a>-bench <em class="arg">iterations</em></h4>
708 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Measure performance.</td><td style='text-align:right;'></td></tr></table>
710 <p>Repeat the entire command for the given number of <em class="arg"
711 >iterations</em> and report the user-time and elapsed time. For instance,
712 consider the following command and its output. Modify the benchmark with the
713 -duration to run the benchmark for a fixed number of seconds and -concurrent
714 to run the benchmark in parallel (requires the OpenMP feature).</p>
716 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -resize 1000% -bench 5 logo.png</span><span class='crtout'>Performance[4]: 5i 0.875657ips 6.880u 0:05.710</span></p>
717 <p>In this example, 5 iterations were completed at 0.875657 iterations per
718 second, using 4 threads and 6.88 seconds of the user's allotted time, for
719 a total elapsed time of 5.71 seconds.</p>
721 <div style="margin: auto;">
722 <h4><a id="bias"></a>-bias <em class="arg">value</em>{<em class="arg">%</em>}</h4>
725 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Add bias when convolving an image.</td><td style='text-align:right;'></td></tr></table>
727 <p>This option shifts the output of <a href="command-line-options.html#convolve">‑convolve</a> so that
728 positive and negative results are relative to the specified bias value. </p>
730 <p>This is important for non-HDRI compilations of ImageMagick when dealing
731 with convolutions that contain negative as well as positive values. This is
732 especially the case with convolutions involving high pass filters or edge
733 detection. Without an output bias, the negative values are clipped at
736 <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
737 negative results without clipping to the color value range
738 (0..QuantumRange).</p>
740 <p>See the discussion on HDRI implementations of ImageMagick on the page <a
741 href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
742 about HDRI go the ImageMagick <a
743 href="http://www.imagemagick.org/Usage/basics/#hdri" >Usage</a> pages or this
745 href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
748 <div style="margin: auto;">
749 <h4><a id="black-point-compensation"></a>-black-point-compensation</h4>
752 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use black point compensation.</td><td style='text-align:right;'></td></tr></table>
754 <div style="margin: auto;">
755 <h4><a id="black-threshold"></a>-black-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
758 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged.</td><td style='text-align:right;'></td></tr></table>
760 <p> The threshold value can be given as a percentage or as an absolute integer
761 value within [0, <em class="QR">QuantumRange</em>] corresponding to the
762 desired <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>
765 <div style="margin: auto;">
766 <h4><a id="blend"></a>-blend <em class="arg">geometry</em></h4>
769 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>blend an image into another by the given absolute value or percent.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
771 <p>Blend will average the images together ('plus') according to the
772 percentages given and each pixels transparency. If only a single percentage
773 value is given it sets the weight of the composite or 'source' image, while
774 the background image is weighted by the exact opposite amount. That is a
775 <kbd>-blend 30%</kbd> merges 30% of the 'source' image with 70% of the
776 'destination' image. Thus it is equivalent to <kbd>-blend 30x70%</kbd>.</p>
779 <div style="margin: auto;">
780 <h4><a id="blue-primary"></a>-blue-primary <em class="arg">x</em>,<em class="arg">y</em></h4>
783 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the blue chromaticity primary point.</td><td style='text-align:right;'></td></tr></table>
785 <div style="margin: auto;">
786 <h4><a id="blue-shift"></a>-blue-shift <em class="arg">factor</em></h4>
789 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a scene at nighttime in the moonlight. Start with a factor of 1.5</td><td style='text-align:right;'></td></tr></table>
791 <div style="margin: auto;">
793 <div style="margin: auto;">
794 <h4><a id="blur"></a>-blur <em class="arg">radius</em><br />-blur <em class="arg">radius</em>x<em class="arg">sigma</em></h4>
797 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reduce image noise and reduce detail levels.</td><td style='text-align:right;'></td></tr></table>
799 <p>Convolve the image with a Gaussian or normal distribution using the given
800 <em class="arg" >Sigma</em> value. The formula is:</p>
802 <div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/>
805 <p>The <em class="arg" >Sigma</em> value is the important argument, and
806 determines the actual amount of blurring that will take place. </p>
808 <p>The <em class="arg" >Radius</em> is only used to determine the size of the
809 array which will hold the calculated Gaussian distribution. It should be an
810 integer. If not given, or set to zero, IM will calculate the largest possible
811 radius that will provide meaningful results for the Gaussian distribution.
814 <p>The larger the <em class="arg" >Radius</em> the slower the
815 operation is. However too small a <em class="arg" >Radius</em>, and sever
816 aliasing effects may result. As a guideline, <em class="arg" >Radius</em>
817 should be at least twice the <em class="arg" >Sigma</em> value, though three
818 times will produce a more accurate result. </p>
820 <p>This option differs from <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a> simply
821 by taking advantage of the separability properties of the distribution. Here
822 we apply a single-dimensional Gaussian matrix in the horizontal direction,
823 then repeat the process in the vertical direction.</p>
825 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
826 pixels which are outside the image proper are blurred into the final result.
830 <div style="margin: auto;">
831 <h4>-blur <em class="arg">Width</em>[x<em class="arg">Height</em>[+<em class="arg">Angle</em>]]</h4>
834 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Variably blur and image according to the overlay mapping.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
836 <p>Each pixel in the overlaid region is replaced with an Elliptical Weighted
837 Average (EWA) of the source image, scaled according to the grayscale
840 <p>The ellipse is weighted with sigma set to the given <em class="arg"
841 >Width</em> and <em class="arg" >Height</em>. The <em class="arg" >Height</em>
842 defaults to the <em class="arg" >Width</em> for a normal circular Gaussian
843 weighting. The <em class="arg" >Angle</em> will rotate the ellipse from
844 horizontal clock-wise. </p>
846 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
847 pixels which are outside the image proper are blurred into the final result.
851 <div style="margin: auto;">
852 <h4><a id="border"></a>-border <em class="arg">geometry</em></h4>
855 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Surround the image with a border of color. </td><td style='text-align:right;'></td></tr></table>
857 <p>Set the width and height using the <em class="arg">size</em> portion of the
858 <em class="arg">geometry</em> 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
861 <p>Set the border color by preceding with the <a
862 href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
864 <p>The <a href="command-line-options.html#border">-border</a> operation is affected by the current <a
865 href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
866 '<kbd>Over</kbd>' composition method. It generates a image of the appropriate
867 size colors by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> before
868 overlaying the original image in the center of this net image. This means that
869 with the default compose method of '<kbd>Over</kbd>' any transparent parts may
870 be replaced by the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
871 <p>See also the <a href="command-line-options.html#frame">-frame</a> option, which has more
874 <div style="margin: auto;">
875 <h4><a id="bordercolor"></a>-bordercolor <em class="arg">color</em></h4>
878 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the border color.</td><td style='text-align:right;'></td></tr></table>
880 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
882 <p>The default border color is <kbd>#DFDFDF</kbd>, <span style="background-color: #dfdfdf;">this shade of gray</span>.</p>
884 <div style="margin: auto;">
885 <h4><a id="borderwidth"></a>-borderwidth <em class="arg">geometry</em> </h4>
888 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the border width.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
890 <div style="margin: auto;">
891 <h4><a id="brightness-contrast"></a>-brightness-contrast <em class="arg">brightness</em><br />-brightness-contrast <em class="arg">brightness</em>{x<em class="arg">contrast</em>}{<em class="arg">%</em>}}</h4>
894 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adjust the brightness and/or contrast of the image.</td><td style='text-align:right;'></td></tr></table>
896 <p>Brightness and Contrast values apply changes to the input image. They are
897 not absolute settings. A brightness or contrast value of zero means no change.
898 The range of values is -100 to +100 on each. Positive values increase the
899 brightness or contrast and negative values decrease the brightness or contrast.
900 To control only contrast, set the brightness=0. To control only brightness,
901 set contrast=0 or just leave it off.</p>
903 <p>You may also use <a href="command-line-options.html#fill">-channel</a> to control which channels to
904 apply the brightness and/or contrast change. The default is to apply the same
905 transformation to all channels.</p>
907 <p>Brightness and Contrast arguments are converted to offset and slope of a
908 linear transform and applied
909 using <a href="command-line-options.html#fill">-function polynomial "slope,offset"</a>.</p>
911 <p>The slope varies from 0 at contrast=-100 to almost vertical at
912 contrast=+100. For brightness=0 and contrast=-100, the result are totally
913 midgray. For brightness=0 and contrast=+100, the result will approach but
914 not quite reach a threshold at midgray; that is the linear transformation
915 is a very steep vertical line at mid gray.</p>
917 <p>Negative slopes, i.e. negating the image, are not possible with this
918 function. All achievable slopes are zero or positive.</p>
920 <p>The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5
921 at brightness=+100. Thus, when contrast=0 and brightness=100, the result is
922 totally white. Similarly, when contrast=0 and brightness=-100, the result is
925 <p>As the range of values for the arguments are -100 to +100, adding the '%'
926 symbol is no different than leaving it off.</p>
928 <div style="margin: auto;">
929 <h4><a id="cache"></a>-cache <em class="arg">threshold</em></h4>
932 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>(This option has been replaced by the <a href='command-line-options.html#limit'>-limit</a> option.)</td><td style='text-align:right;'></td></tr></table>
934 <div style="margin: auto;">
935 <h4><a id="caption"></a>-caption <em class="arg">string</em></h4>
938 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Assign a caption to an image.</td><td style='text-align:right;'></td></tr></table>
940 <p>This option sets the caption meta-data of an image read in after this
941 option has been given. To modify a caption of images already in memory use
942 "<kbd><a href="command-line-options.html#set">-set</a> caption</kbd>". </p>
944 <p>The caption can contain special format characters listed in the <a
945 href="escape.html">Format and
946 Print Image Properties</a>. These attributes are expanded when the caption
947 is finally assigned to the individual images. </p>
949 <p>If the first character of <em class="arg">string</em> is <em
950 class="arg">@</em>, the image caption is read from a file titled by the
951 remaining characters in the string. Comments read in from a file are literal;
952 no embedded formatting characters are recognized.</p>
954 <p>Caption meta-data is not visible on the image itself. To do that use the
955 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
961 -caption "%m:%f %wx%h" bird.miff
964 <p>produces an image caption of <kbd>MIFF:bird.miff 512x480</kbd> (assuming
965 that the image <kbd>bird.miff</kbd> has a width of 512 and a height of
969 <div style="margin: auto;">
970 <h4><a id="cdl"></a>-cdl <em class="arg">filename</em></h4>
973 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color correct with a color decision list.</td><td style='text-align:right;'></td></tr></table>
975 <p>Here is an example color correction collection:</p>
978 <?xml version="1.0" encoding="UTF-8"?>
979 <ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2">
980 <ColorCorrection id="cc06668">
982 <Slope> 0.9 1.2 0.5 </Slope>
983 <Offset> 0.4 -0.5 0.6 </Offset>
984 <Power> 1.0 0.8 1.5 </Power>
987 <Saturation> 0.85 </Saturation>
989 </ColorCorrection>
990 </ColorCorrectionCollection>
993 <div style="margin: auto;">
994 <h4><a id="channel"></a>-channel <em class="arg">type</em></h4>
997 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify those image color channels to which subsequent operators are limited.</td><td style='text-align:right;'></td></tr></table>
999 <p>Choose from: <kbd>Red</kbd>, <kbd>Green</kbd>, <kbd>Blue</kbd>,
1000 <kbd>Alpha</kbd>, <kbd>Cyan</kbd>, <kbd>Magenta</kbd>, <kbd>Yellow</kbd>,
1001 <kbd>Black</kbd>, <kbd>Opacity</kbd>, <kbd>Index</kbd>, <kbd>RGB</kbd>,
1002 <kbd>RGBA</kbd>, <kbd>CMYK</kbd>, or <kbd>CMYKA</kbd>.</p>
1004 <p>The channels above can also be specified as a comma-separated list or can be
1005 abbreviated as a concatenation of the letters '<kbd>R</kbd>', '<kbd>G</kbd>',
1006 '<kbd>B</kbd>', '<kbd>A</kbd>', '<kbd>O</kbd>', '<kbd>C</kbd>',
1007 '<kbd>M</kbd>', '<kbd>Y</kbd>', '<kbd>K</kbd>'.
1009 For example, to only select the <kbd>Red</kbd> and <kbd>Blue</kbd> channels
1010 you can either use </p>
1014 <p>or you can use the short hand form</p>
1019 <p>All the channels that are present in an image can be specified using the
1020 special channel type <kbd>All</kbd>. Not all operators are 'channel capable',
1021 but generally any operators that are generally 'grey-scale' image operators,
1022 will understand this setting. See individual operator documentation. </p>
1026 <p>On top of the normal channel selection an extra flag can be specified,
1027 '<kbd>Sync</kbd>'. This is turned on by default and if set means that
1028 operators that understand this flag should perform: cross-channel
1029 synchronization of the channels. If not specified, then most grey-scale
1030 operators will apply their image processing operations to each individual
1031 channel (as specified by the rest of the <a href="command-line-options.html#channel">-channel</a>
1032 setting) completely independently from each other. </p>
1034 <p>For example for operators such as <a href="command-line-options.html#auto-level">-auto-level</a> and
1035 <a href="command-line-options.html#auto-gamma">-auto-gamma</a> the color channels are modified
1036 together in exactly the same way so that colors will remain in-sync. Without
1037 it being set, then each channel is modified separately and
1038 independently, which may produce color distortion. </p>
1040 <p>The <a href="command-line-options.html#morphology">-morphology</a> '<kbd>Convolve</kbd>' method
1041 and the <a href="command-line-options.html#compose">-compose</a> mathematical methods, also understands
1042 the '<kbd>Sync</kbd>' flag to modify the behaviour of pixel colors according
1043 to the alpha channel (if present). That is to say it will modify the image
1044 processing with the understanding that fully-transparent colors should not
1045 contribute to the final result. </p>
1047 <p>Basically, by default, operators work with color channels in synchronous, and
1048 treats transparency as special, unless the <a href="command-line-options.html#channel">-channel</a>
1049 setting is modified so as to remove the effect of the '<kbd>Sync</kbd>' flag.
1050 How each operator does this depends on that operators current implementation.
1051 Not all operators understands this flag at this time, but that is changing.
1054 <p>To print a complete list of channel types, use <a href="command-line-options.html#list">-list
1059 <p>By default, ImageMagick sets <a href="command-line-options.html#channel">-channel</a> to the value
1060 '<kbd>RGBK,sync</kbd>', which specifies that operators act on all color
1061 channels except the transparency channel, and that all the color channels are
1062 to be modified in exactly the same way, with an understanding of transparency
1063 (depending on the operation being applied). The 'plus' form <a
1064 href="command-line-options.html#channel" >+channel</a> will reset the value back to this default. </p>
1066 <p>Options that are affected by the <a href="command-line-options.html#channel" >-channel</a> setting
1067 include the following.
1069 <a href="command-line-options.html#auto-gamma">-auto-gamma</a>,
1070 <a href="command-line-options.html#auto-level">-auto-level</a>,
1071 <a href="command-line-options.html#black-threshold">-black-threshold</a>,
1072 <a href="command-line-options.html#blur">-blur</a>,
1073 <a href="command-line-options.html#clamp">-clamp</a>,
1074 <a href="command-line-options.html#clut">-clut</a>,
1075 <a href="command-line-options.html#combine">-combine</a>,
1076 <a href="command-line-options.html#composite">-composite</a> (Mathematical compose methods only),
1077 <a href="command-line-options.html#convolve">-convolve</a>,
1078 <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a>,
1079 <a href="command-line-options.html#evaluate">-evaluate</a>,
1080 <a href="command-line-options.html#function">-function</a>,
1081 <a href="command-line-options.html#fx">-fx</a>,
1082 <a href="command-line-options.html#gaussian-blur">-gaussian-blur</a>,
1083 <a href="command-line-options.html#hald-clut">-hald-clut</a>,
1084 <a href="command-line-options.html#motion-blur">-motion-blur</a>,
1085 <a href="command-line-options.html#morphology">-morphology</a>,
1086 <a href="command-line-options.html#negate">-negate</a>,
1087 <a href="command-line-options.html#normalize">-normalize</a>,
1088 <a href="command-line-options.html#ordered-dither">-ordered-dither</a>,
1089 <a href="command-line-options.html#radial-blur">-radial-blur</a>,
1090 <a href="command-line-options.html#random-threshold">-random-threshold</a>,
1091 <a href="command-line-options.html#separate">-separate</a>,
1092 <a href="command-line-options.html#threshold">-threshold</a>, and
1093 <a href="command-line-options.html#white-threshold">-white-threshold</a>.
1096 <p>Warning, some operators behave differently when the <a href="command-line-options.html#channel"
1097 >+channel</a> default setting is in effect, verses ANY user defined <a
1098 href="command-line-options.html#channel" >-channel</a> setting (including the equivalent of the
1099 default). These operators have yet to be made to understand the newer 'Sync'
1102 <p>For example <a href="command-line-options.html#threshold">-threshold</a> will by default gray-scale
1103 the image before thresholding, if no <a href="command-line-options.html#channel" >-channel</a> setting
1104 has been defined. This is not 'Sync flag controlled, yet. </p>
1106 <p>Also some operators such as <a href="command-line-options.html#blur">-blur</a>, <a
1107 href="command-line-options.html#gaussian-blur">-gaussian-blur</a>, will modify their handling of the
1108 color channels if the '<kbd>alpha</kbd>' channel is also enabled by <a
1109 href="command-line-options.html#channel" >-channel</a>. Generally this done to ensure that
1110 fully-transparent colors are treated as being fully-transparent, and thus any
1111 underlying 'hidden' color has no effect on the final results. Typically
1112 resulting in 'halo' effects. The newer <a href="command-line-options.html#morphology">-morphology</a>
1113 convolution equivalents however does have a understanding of the 'Sync' flag
1114 and will thus handle transparency correctly by default. </p>
1116 <p>As a alpha channel is optional within images, some operators will read the
1117 color channels of an image as a greyscale alpha mask, when the image has no
1118 alpha channel present, and the <a href="command-line-options.html#channel" >-channel</a> setting tells
1119 the operator to apply the operation using alpha channels. The <a
1120 href="command-line-options.html#clut">-clut</a> operator is a good example of this. </p>
1124 <div style="margin: auto;">
1125 <h4><a id="charcoal"></a>-charcoal <em class="arg">factor</em></h4>
1128 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Simulate a charcoal drawing.</td><td style='text-align:right;'></td></tr></table>
1130 <div style="margin: auto;">
1131 <h4><a id="chop"></a>-chop <em class="arg">geometry</em></h4>
1134 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Remove pixels from the interior of an image.</td><td style='text-align:right;'></td></tr></table>
1136 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <em class="arg">width</em>
1137 and <em class="arg">height</em> given in the of the <em class="arg">size</em>
1138 portion of the <em class="arg">geometry</em> argument give the number of
1139 columns and rows to remove. The <em class="arg">offset</em> portion of
1140 the <em class="arg">geometry</em> argument is influenced by
1141 a <a href="command-line-options.html#gravity">-gravity</a> setting, if present.</p>
1143 <p>The <a href="command-line-options.html#chop">-chop</a> option removes entire rows and columns,
1144 and moves the remaining corner blocks leftward and upward to close the gaps.</p>
1146 <p>While it can remove internal rows and columns of pixels, it is more
1147 typically used with as <a href="command-line-options.html#gravity">-gravity</a> setting and zero
1148 offsets so as to remove a single edge from an image. Compare this to <a
1149 href="command-line-options.html#shave" >-shave</a> which removes equal numbers of pixels from oppisite
1150 sides of the image. </p>
1152 <p>Using <a href="command-line-options.html#chop">-chop</a> effectively undoes the results of a <a
1153 href="command-line-options.html#splice">-splice</a> that was given the same <em
1154 class="arg">geometry</em> and <a href="command-line-options.html#gravity">-gravity</a> settings. </p>
1156 <div style="margin: auto;">
1157 <h4><a id="clamp"></a>-clamp</h4>
1160 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Restrict image colors from 0 to the quantum depth.</td><td style='text-align:right;'></td></tr></table>
1163 <div style="margin: auto;">
1164 <h4><a id="clip"></a>-clip</h4>
1167 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply the clipping path if one is present.</td><td style='text-align:right;'></td></tr></table>
1169 <p>If a clipping path is present, it is applied to subsequent operations.</p>
1171 <p>For example, in the command</p>
1173 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -clip -negate cockatoo.tif negated.tif</span></p>
1174 <p>only the pixels within the clipping path are negated.</p>
1176 <p>The <a href="command-line-options.html#clip">-clip</a> feature requires the XML library. If the XML
1177 library is not present, the option is ignored.</p>
1179 <div style="margin: auto;">
1180 <h4><a id="clip-mask"></a>-clip-mask</h4>
1183 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Clip the image as defined by this mask.</td><td style='text-align:right;'></td></tr></table>
1185 <p>Use the given image as a 'do-not-modify' mask of the current images in the
1186 current image sequence. Assuming the clipmask is a greyscale image the same
1187 size at the one already in memory, any areas that is white will not be
1188 modified by any of the 'image processing operators' that follow, until the
1189 mask is removed. Pixels in the black areas of the clip mask will be modified
1192 <p>In some ways this is similar to (though not the same) as defining
1193 a rectangular <a href="command-line-options.html#region" >-region</a>, or using the negative of the
1194 mask (thrid) image in a three image <a href="command-line-options.html#composite" >-composite</a>,
1198 <div style="margin: auto;">
1199 <h4><a id="clip-path"></a>-clip-path <em class="arg">id</em></h4>
1202 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Clip along a named path from the 8BIM profile.</td><td style='text-align:right;'></td></tr></table>
1204 <p>This is almost identical to <a href="command-line-options.html#clip">-clip</a>. </p>
1207 <div style="margin: auto;">
1208 <h4><a id="clone"></a>-clone <em class="arg">index(s)</em></h4>
1211 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make a clone of an image (or images).</td><td style='text-align:right;'></td></tr></table>
1213 <p>Inside parenthesis (where the operator is normally used) it will make a
1214 clone of the images from the last 'pushed' image sequence, and adds them to
1215 the end of the current image sequence. Outside parenthesis
1216 (not recommended) it clones the images from the current image sequence. </p>
1218 <p>Specify the image by its index in the sequence. The first image is index
1219 0. Negative indexes are relative to the end of the sequence; for
1220 example, <kbd>−1</kbd>
1221 represents the last image of the sequence. Specify a range of images with a
1222 dash (e.g. <kbd>0−4</kbd>). Separate multiple indexes with commas but no
1223 spaces (e.g. <kbd>0,2,5</kbd>). A value of '<kbd>0−−1</kbd> will
1224 effectively clone all the images. </p>
1226 <p>The <a href="command-line-options.html#clone">+clone</a> will simply make a copy of the last image
1227 in the image sequence, and is thus equivalent to using a argument of
1228 '<kbd>−1</kbd>'. </p>
1230 <div style="margin: auto;">
1231 <h4><a id="clut"></a>-clut</h4>
1234 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Replace the channel values in the first image using each
1235 corresponding channel in the second image as a <b>c</b>olor
1236 <b>l</b>ook<b>u</b>p <b>t</b>able.</td><td style='text-align:right;'></td></tr></table>
1238 <p>The second (LUT) image is ordinarily a gradient image containing the
1239 histogram mapping of how each channel should be modified. Typically it is a
1240 either a single row or column image of replacement color values. If larger
1241 than a single row or column, values are taken from a diagonal line from
1242 top-left to bottom-right corners.</p>
1244 <p>The lookup is further controlled by the <a
1245 href="command-line-options.html#interpolate">-interpolate</a> setting, which is especially handy for an
1246 LUT which is not the full length needed by the ImageMagick installed Quality
1247 (Q) level. Good settings for this are the '<kbd>bilinear</kbd>' and
1248 '<kbd>bicubic</kbd>' interpolation settings, which give smooth color
1249 gradients, and the '<kbd>integer</kbd>' setting for a direct, unsmoothed
1250 lookup of color values. </p>
1252 <p>This operator is especially suited to replacing a grayscale image with a
1253 specific color gradient from the CLUT image. </p>
1255 <p>Only the channel values defined by the <a href="command-line-options.html#channel">-channel</a>
1256 setting will have their values replaced. In particular, since the default <a
1257 href="command-line-options.html#channel">-channel</a> setting is <kbd>RGB</kbd>, this means that
1258 transparency (alpha/matte channel) is not affected, unless the <a
1259 href="command-line-options.html#channel">-channel</a> setting is modified. When the alpha channel is
1260 set, it is treated by the <a href="command-line-options.html#clut" >-clut</a> operator in the same way
1261 as the other channels, implying that alpha/matte values are replaced using the
1262 alpha/matte values of the original image. </p>
1264 <p>If either the image being modified, or the lookup image, contains no
1265 transparency (i.e. <a href="command-line-options.html#alpha" >-alpha</a> is turned 'off') but the <a
1266 href="command-line-options.html#channel">-channel</a> setting includes alpha replacement, then it is
1267 assumed that image represents a gray-scale gradient which is used for the
1268 replacement alpha values. That is you can use a gray-scale CLUT image to
1269 adjust a existing images alpha channel, or you can color a gray-scale image
1270 using colors form CLUT containing the desired colors, including transparency.
1273 <p>See also <a href="command-line-options.html#hald-clut" >-hald-clut</a> which replaces colors
1274 according to the lookup of the full color RGB value from a 2D representation
1275 of a 3D color cube. </p>
1278 <div style="margin: auto;">
1279 <h4><a id="coalesce"></a>-coalesce</h4>
1282 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation.</td><td style='text-align:right;'></td></tr></table>
1284 <p>Overlay each image in an image sequence according to
1285 its <a href="command-line-options.html#dispose">-dispose</a> meta-data, to reproduce the look of
1286 an animation at each point in the animation sequence. All images should be
1287 the same size, and are assigned appropriate GIF disposal settings for the
1288 animation to continue working as expected as a GIF animation. Such frames
1289 are more easily viewed and processed than the highly optimized GIF overlay
1292 <p>The animation can be re-optimized after processing using
1293 the <a href="command-line-options.html#layers">-layers</a> method '<kbd>optimize</kbd>', although
1294 there is no guarantee that the restored GIF animation optimization is
1295 better than the original. </p>
1298 <div style="margin: auto;">
1299 <h4><a id="colorize"></a>-colorize <em class="arg">value</em></h4>
1302 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Colorize the image by an amount specified by <em class="arg">value</em> using the color specified by the most recent <a href="command-line-options.html#fill" >-fill</a> setting.</td><td style='text-align:right;'></td></tr></table>
1304 <p>Specify the amount of colorization as a percentage. Separate colorization
1305 values can be applied to the red, green, and blue channels of the image with
1306 a comma-delimited list of colorization
1307 values (e.g., <kbd>-colorize 0,0,50</kbd>).</p>
1309 <div style="margin: auto;">
1310 <h4><a id="colormap"></a>-colormap <em class="arg">type</em></h4>
1313 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Define the colormap type.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
1315 <p>The <em class="arg">type</em> can be <kbd>shared</kbd> or <kbd>private</kbd>.</p>
1317 <p>This option only applies when the default X server visual
1318 is <kbd>PseudoColor</kbd> or <kbd>GrayScale</kbd>. Refer
1319 to <a href="command-line-options.html#visual">-visual</a> for more details. By default,
1320 a shared colormap is allocated. The image shares colors with
1321 other X clients. Some image colors could be approximated,
1322 therefore your image may look very different than intended.
1323 If <kbd>private</kbd> is chosen, the image colors appear exactly
1324 as they are defined. However, other clients may go <em>technicolor</em>
1325 when the image colormap is installed.</p>
1327 <div style="margin: auto;">
1328 <h4><a id="colors"></a>-colors <em class="arg">value</em></h4>
1331 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the preferred number of colors in the image.</td><td style='text-align:right;'></td></tr></table>
1333 <p>The actual number of colors in the image may be less than your request,
1334 but never more. Note that this a color reduction option. Images with fewer
1335 unique colors than specified by <em class="arg">value</em> will have any
1336 duplicate or unused colors removed. The ordering of an existing color
1337 palette may be altered. When converting an image from color to grayscale,
1338 it is more efficient to convert the image to the gray colorspace before
1339 reducing the number of colors. Refer to
1340 the <a href="quantize.html">
1341 color reduction algorithm</a> for more details.</p>
1343 <div style="margin: auto;">
1344 <h4><a id="color-matrix"></a>-color-matrix <em class="arg">matrix</em></h4>
1347 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply color correction to the image.</td><td style='text-align:right;'></td></tr></table>
1349 <p>This option permits saturation changes, hue rotation, luminance to alpha,
1350 and various other effects. Although variable-sized transformation matrices
1351 can be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6
1352 for CMYKA (or RGBA with offsets). The matrix is similar to those used by
1353 Adobe Flash except offsets are in column 6 rather than 5 (in support of
1354 CMYKA images) and offsets are normalized (divide Flash offset by 255).</p>
1356 <p>As an example, to add contrast to an image with offsets, try this command:</p>
1359 convert kittens.jpg -color-matrix \
1360 " 1.5 0.0 0.0 0.0, 0.0, -0.157 \
1361 0.0 1.5 0.0 0.0, 0.0, -0.157 \
1362 0.0 0.0 1.5 0.0, 0.0, -0.157 \
1363 0.0 0.0 0.0 1.0, 0.0, 0.0 \
1364 0.0 0.0 0.0 0.0, 1.0, 0.0 \
1365 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
1367 <div style="margin: auto;">
1368 <h4><a id="colorspace"></a>-colorspace <em class="arg">value</em></h4>
1371 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the image colorspace.</td><td style='text-align:right;'></td></tr></table>
1378 OHTA Rec601Luma Rec601YCbCr Rec709Luma
1379 Rec709YCbCr RGB sRGB Transparent
1384 <p>To print a complete list of colorspaces, use <a href="command-line-options.html#list">-list
1387 <p>For a more accurate color conversion to or from the RGB, CMYK, or grayscale
1388 colorspaces, use the <a href="command-line-options.html#profile">-profile</a> option.</p>
1391 <caption>Conversion Of RGB To Other Color Spaces</caption>
1392 <tr><th align="left" valign="middle">CMY</th></tr>
1393 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>−R</td></tr>
1394 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>−G</td></tr>
1395 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>−B</td></tr>
1396 <tr><th align="left" valign="middle">CMYK — starts with CMY from above</th></tr>
1397 <tr><td align="left" valign="middle">K=min(C,Y,M)</td></tr>
1398 <tr><td align="left" valign="middle">C=<em class="QR">QuantumRange</em>*(C−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1399 <tr><td align="left" valign="middle">M=<em class="QR">QuantumRange</em>*(M−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1400 <tr><td align="left" valign="middle">Y=<em class="QR">QuantumRange</em>*(Y−K)/(<em class="QR">QuantumRange</em>−K)</td></tr>
1402 <tr><th align="left" valign="middle">Gray</th></tr>
1403 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr>
1405 <tr><th align="left" valign="middle">HSB — Hue, Saturation, Brightness; like a cone peak downward</th></tr>
1406 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1407 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr>
1408 <tr><td align="left" valign="middle">B=distance along axis from bottom upward; B=max(R,G,B); <em>intensity-like</em></td></tr>
1410 <tr><th align="left" valign="middle">HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom</th></tr>
1411 <tr><td align="left" valign="middle">H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green</td></tr>
1412 <tr><td align="left" valign="middle">S=distance from axis outward</td></tr>
1413 <tr><td align="left" valign="middle">L=distance along axis from bottom upward; L=0.5*max(R,G,B) + 0.5*min(R,G,B); <em>intensity-like</em></td></tr>
1415 <tr><th align="left" valign="middle">HWB — Hue, Whiteness, Blackness</th></tr>
1416 <tr><td align="left" valign="middle">Hue (complicated equation)</td></tr>
1417 <tr><td align="left" valign="middle">Whiteness (complicated equation)</td></tr>
1418 <tr><td align="left" valign="middle">Blackness (complicated equation)</td></tr>
1420 <tr><th align="left" valign="middle">LAB</th></tr>
1421 <tr><td align="left" valign="middle">L (complicated equation relating X,Y,Z)</td></tr>
1422 <tr><td align="left" valign="middle">A (complicated equation relating X,Y,Z)</td></tr>
1423 <tr><td align="left" valign="middle">B (complicated equation relating X,Y,Z)</td></tr>
1425 <tr><th align="left" valign="middle">LOG</th></tr>
1426 <tr><td align="left" valign="middle">I1 (complicated equation involving logarithm of R)</td></tr>
1427 <tr><td align="left" valign="middle">I2 (complicated equation involving logarithm of G)</td></tr>
1428 <tr><td align="left" valign="middle">I3 (complicated equation involving logarithm of B)</td></tr>
1430 <tr><th align="left" valign="middle">OHTA — approximates principal components transformation</th></tr>
1431 <tr><td align="left" valign="middle">I1=0.33333*R+0.33334*G+0.33333*B; <em>intensity-like</em></td></tr>
1432 <tr><td align="left" valign="middle">I2=(0.50000*R+0.00000*G−0.50000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1433 <tr><td align="left" valign="middle">I3=(−0.25000*R+0.50000*G−0.25000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1435 <tr><th align="left" valign="middle">Rec601Luma</th></tr>
1436 <tr><td align="left" valign="middle">Gray = 0.29900*R+0.58700*G+0.11400*B</td></tr>
1438 <tr><th align="left" valign="middle">Rec601YCbCr</th></tr>
1439 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr>
1440 <tr><td align="left" valign="middle">Cb=(−0.168736*R-0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1441 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1443 <tr><th align="left" valign="middle">Rec709Luma</th></tr>
1444 <tr><td align="left" valign="middle">Gray=0.21260*R+0.71520*G+0.07220*B</td></tr>
1446 <tr><th align="left" valign="middle">Rec709YCbCr</th></tr>
1447 <tr><td align="left" valign="middle">Y=0.212600*R+0.715200*G+0.072200*B; <em>intensity-like</em></td></tr>
1448 <tr><td align="left" valign="middle">Cb=(−0.114572*R−0.385428*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1449 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.454153*G−0.045847*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1451 <tr><th align="left" valign="middle">sRGB</th></tr>
1452 <tr><td align="left" valign="middle">if R ≤ .04045 then Rs=R/12.92 else Rs=((R+.055)/1.055)^2.4</td></tr>
1453 <tr><td align="left" valign="middle">if G ≤ .04045 then Gs=B/12.92 else Gs=((G+.055)/1.055)^2.4</td></tr>
1454 <tr><td align="left" valign="middle">if B ≤ .04045 then Bs=B/12.92 else Bs=((B+.055)/1.055)^2.4</td></tr>
1456 <tr><th align="left" valign="middle">XYZ</th></tr>
1457 <tr><td align="left" valign="middle">X=0.4124240*R+0.3575790*G+0.1804640*B</td></tr>
1458 <tr><td align="left" valign="middle">Y=0.2126560*R+0.7151580*G+0.0721856*B</td></tr>
1459 <tr><td align="left" valign="middle">Z=0.0193324*R+0.1191930*G+0.9504440*B</td></tr>
1461 <tr><th align="left" valign="middle">YCC</th></tr>
1462 <tr><td align="left" valign="middle">Y=(0.29900*R+0.58700*G+0.11400*B) (with complicated scaling); <em>intensity-like</em></td></tr>
1463 <tr><td align="left" valign="middle">C1=(−0.29900*R−0.58700*G+0.88600*B) (with complicated scaling)</td></tr>
1464 <tr><td align="left" valign="middle">C2=(0.70100*R−0.58700*G−0.11400*B) (with complicated scaling)</td></tr>
1466 <tr><th align="left" valign="middle">YCbCr</th></tr>
1467 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr>
1468 <tr><td align="left" valign="middle">Cb=(−0.168736*R−0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1469 <tr><td align="left" valign="middle">Cr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1471 <tr><th align="left" valign="middle">YIQ</th></tr>
1472 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr>
1473 <tr><td align="left" valign="middle">I=(0.59600*R−0.27400*G−0.32200*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1474 <tr><td align="left" valign="middle">Q=(0.21100*R−0.52300*G+0.31200*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1476 <tr><th align="left" valign="middle">YPbPr</th></tr>
1477 <tr><td align="left" valign="middle">Y=0.299000*R+0.587000*G+0.114000*B; <em>intensity-like</em></td></tr>
1478 <tr><td align="left" valign="middle">Pb=(−0.168736*R−0.331264*G+0.500000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1479 <tr><td align="left" valign="middle">Pr=(0.500000*R−0.418688*G−0.081312*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1481 <tr><th align="left" valign="middle">YUV</th></tr>
1482 <tr><td align="left" valign="middle">Y=0.29900*R+0.58700*G+0.11400*B; <em>intensity-like</em></td></tr>
1483 <tr><td align="left" valign="middle">U=(−0.14740*R−0.28950*G+0.43690*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1484 <tr><td align="left" valign="middle">V=(0.61500*R−0.51500*G−0.10000*B)*(<em class="QR">QuantumRange</em>+1)/2</td></tr>
1487 <div style="margin: auto;">
1488 <h4><a id="combine"></a>-combine</h4>
1491 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Combine one or more images into a single image.</td><td style='text-align:right;'></td></tr></table>
1493 <p>The channels (previously set by <a href="command-line-options.html#channel">-channel</a>) of the
1494 combined image are taken from the grayscale values of each image in the
1495 sequence, in order. For the default -channel setting of <kbd>RGB</kbd>, this
1496 means the first image is assigned to the <kbd>Red</kbd> channel, the second
1497 to the <kbd>Green</kbd> channel, the third to the <kbd>Blue</kbd>.</p>
1499 <p>This option can be thought of as the inverse to <a
1500 href="command-line-options.html#separate">-separate</a>, so long as the channel settings are the same.
1501 Thus, in the following example, the final image should be a copy of the
1504 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert original.png -channel RGB -separate sepimage.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \ <br/> -combine imagecopy.png</span></p>
1505 <div style="margin: auto;">
1506 <h4><a id="comment"></a>-comment <em class="arg">string</em></h4>
1509 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Embed a comment in an image.</td><td style='text-align:right;'></td></tr></table>
1511 <p>This option sets the comment meta-data of an image read in after this
1512 option has been given. To modify a comment of images already in memory use
1513 "<kbd><a href="command-line-options.html#set">-set</a> comment</kbd>". </p>
1515 <p>The comment can contain special format characters listed in the <a
1516 href="escape.html">Format and
1517 Print Image Properties</a>. These attributes are expanded when the comment
1518 is finally assigned to the individual images. </p>
1520 <p>If the first character of <em class="arg">string</em> is <em
1521 class="arg">@</em>, the image comment is read from a file titled by the
1522 remaining characters in the string. Comments read in from a file are literal;
1523 no embedded formatting characters are recognized.</p>
1525 <p>Comment meta-data are not visible on the image itself. To do that use the
1526 <a href="command-line-options.html#annotate">-annotate</a> or <a href="command-line-options.html#draw">-draw</a> options
1532 -comment "%m:%f %wx%h" bird.miff
1535 <p>produces an image comment of <kbd>MIFF:bird.miff 512x480</kbd> (assuming
1536 that the image <kbd>bird.miff</kbd> has a width of 512 and a height of
1539 <div style="margin: auto;">
1540 <h4><a id="compose"></a>-compose <em class="arg">operator</em></h4>
1543 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the type of image composition.</td><td style='text-align:right;'></td></tr></table>
1545 <p>See <a href="compose.html">Alpha Compositing</a> for
1546 a detailed discussion of alpha compositing.</p>
1548 <p>This setting effects image processing operators that merge two (or more)
1549 images together in some way. This includes the operators,
1550 <a href="command-line-options.html#composite">-composite</a>,
1551 <a href="command-line-options.html#layers">-layers</a> composite,
1552 <a href="command-line-options.html#flatten">-flatten</a>,
1553 <a href="command-line-options.html#mosaic">-mosaic</a>,
1554 <a href="command-line-options.html#layers">-layers</a> merge,
1555 <a href="command-line-options.html#border">-border</a>,
1556 <a href="command-line-options.html#frame">-frame</a>,
1557 and <a href="command-line-options.html#extent">-extent</a>. </p>
1559 <p>It is also one of the primary options for the "<kbd>composite</kbd>"
1563 <div style="margin: auto;">
1564 <h4><a id="composite"></a>-composite</h4>
1567 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Perform alpha composition on two images and an optional mask</td><td style='text-align:right;'></td></tr></table>
1569 <p>Take the first image 'destination' and overlay the second 'source' image
1570 according to the current <a href="command-line-options.html#compose">-compose</a> setting. The location
1571 of the 'source' or 'overlay' image is controlled according to <a
1572 href="command-line-options.html#geometry" >-geometry</a>, and <a href="command-line-options.html#geometry" >-geometry</a>
1575 <p>If a third image is given this is treated as a gray-scale 'mask' image
1576 relative to the first 'destination' image. This mask will limit what parts of
1577 the destination can be modified by the image composition. However for the
1578 '<kbd>displace</kbd>' compose method, the mask is used to provide a separate
1579 Y-displacement image instead. </p>
1581 <p>If a <a href="command-line-options.html#compose">-compose</a> method requires extra numerical
1582 arguments or flags these can be provided by setting the <a
1583 href="command-line-options.html#set">-set</a> '<kbd class="arg">option:compose:args</kbd>'
1584 appropriately for the compose method. </p>
1586 <p>Some <a href="command-line-options.html#compose">-compose</a> methods can modify the 'destination'
1587 image outside the overlay area. You can disable this by setting the special <a
1588 href="command-line-options.html#set">-set</a> '<kbd class="arg">option:compose:outside-overlay</kbd>'
1589 to '<kbd>false</kbd>'. </p>
1592 <div style="margin: auto;">
1593 <h4><a id="compress"></a>-compress <em class="arg">type</em></h4>
1596 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use pixel compression specified by <em class="arg">type</em> when writing the image.</td><td style='text-align:right;'></td></tr></table>
1598 <p>Choices are: <kbd class="arg">None</kbd>, <kbd class="arg">BZip</kbd>, <kbd
1599 class="arg">Fax</kbd>, <kbd class="arg">Group4</kbd>, <kbd
1600 class="arg">JPEG</kbd>, <kbd class="arg">JPEG2000</kbd>, <kbd
1601 class="arg">Lossless</kbd>, <kbd class="arg">LZW</kbd>, <kbd
1602 class="arg">RLE</kbd> or <kbd class="arg">Zip</kbd>.</p>
1604 <p>To print a complete list of compression types, use <a href="command-line-options.html#list">-list
1607 <p>Specify <a href="command-line-options.html#compress">+compress</a> to store the binary image in an
1608 uncompressed format. The default is the compression type of the specified
1611 <p>If <kbd>LZW</kbd> compression is specified but LZW compression has not been
1612 enabled, the image data is written in an uncompressed LZW format that can be
1613 read by LZW decoders. This may result in larger-than-expected GIF files.</p>
1615 <p><kbd>Lossless</kbd> refers to lossless JPEG, which is only available if the
1616 JPEG library has been patched to support it. Use of lossless JPEG is generally
1617 not recommended.</p>
1620 When writing an ICO file, you may request that the images be encoded in
1621 PNG format, by specifying <kbd>Zip</kbd> compression.</p>
1624 When writing a JNG file, specify <kbd>Zip</kbd> compression to request that
1625 the alpha channel be encoded in PNG "IDAT" format, or <kbd>JPEG</kbd>
1626 to request that it be encoded in JPG "JDAA" format.</p>
1628 <p>Use the <a href="command-line-options.html#quality">-quality</a> option to set the compression level
1629 to be used by JPEG, PNG, MIFF, and MPEG encoders.
1630 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to set the
1631 sampling factor to be used by JPEG, MPEG, and YUV encoders for down-sampling
1632 the chroma channels.</p>
1634 <div style="margin: auto;">
1635 <h4><a id="contrast"></a>-contrast</h4>
1638 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Enhance or reduce the image contrast.</td><td style='text-align:right;'></td></tr></table>
1640 <p>This option enhances the intensity differences between the lighter and
1641 darker elements of the image. Use <a href="command-line-options.html#contrast">-contrast</a> to enhance
1642 the image or <a href="command-line-options.html#contrast">+contrast</a> to reduce the image
1645 <p>For a more pronounced effect you can repeat the option:</p>
1647 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -contrast -contrast rose_c2.png</span></p>
1648 <div style="margin: auto;">
1649 <h4><a id="contrast-stretch"></a>-contrast-stretch <em class="arg">black-point</em><br />-contrast-stretch <em class="arg">black-point</em>{x<em class="arg">white-point</em>}{<em class="arg">%</em>}}</h4>
1652 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Increase the contrast in an image by <em>stretching</em> the range of intensity values.</td><td style='text-align:right;'></td></tr></table>
1654 <p>While performing the stretch, black-out at most <em
1655 class="arg" >black-point</em> pixels and white-out at most <em
1656 class="arg" >white-point</em> pixels. Or, if percent is used, black-out at most
1657 <em class="arg" >black-point %</em> pixels and white-out at most <em
1658 class="arg" >white-point %</em> pixels.</p>
1660 <p>Prior to ImageMagick 6.4.7-0, <a href="command-line-options.html#contrast-stretch"
1661 >-contrast-stretch</a> will black-out at most <em class="arg"
1662 >black-point</em> pixels and white-out at most <em class="arg" >total pixels
1663 minus white-point</em> pixels. Or, if percent is used, black-out at most <em
1664 class="arg">black-point %</em> pixels and white-out at most <em class="arg"
1665 >100% minus white-point %</em> pixels.</p>
1667 <p>Note that <kbd>-contrast-stretch 0</kbd> will modify the image such that
1668 the image's min and max values are stretched to 0 and <em class="QR"
1669 >QuantumRange</em>, respectively, without any loss of data due to burn-out or
1670 clipping at either end. This is not the same as <a href="command-line-options.html#normalize"
1671 >-normalize</a>, which is equivalent to <kbd>-contrast-stretch 0.15x0.05%</kbd> (or
1672 prior to ImageMagick 6.4.7-0, <kbd>-contrast-stretch 2%x99%</kbd>).</p>
1674 <p>Internally operator works by creating a histogram bin, and then uses that
1675 bin to modify the image. As such some colors may be merged together when they
1676 originally fell into the same 'bin'. </p>
1678 <p>All the channels are normalized in concert by the came amount so as to
1679 preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
1680 setting is in use. Specifying any other <a href="command-line-options.html#channel" >-channel</a>
1681 setting will normalize the RGB channels independently.</p>
1683 <p>See also <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
1684 normalization of mathematical images. </p>
1686 <p>This operator is under review for re-development. </p>
1689 <div style="margin: auto;">
1690 <h4><a id="convolve"></a>-convolve <em class="arg">kernel</em></h4>
1693 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Convolve an image with a user-supplied convolution kernel.</td><td style='text-align:right;'></td></tr></table>
1695 <p>The <em class="arg">kernel</em> is a matrix specified as
1696 a comma-separated list of integers (with no spaces), ordered left-to right,
1697 starting with the top row. Presently, only odd-dimensioned kernels are
1698 supported, and therefore the number of entries in the specified <em
1699 class="arg">kernel</em> must be 3<sup>2</sup>=9, 5<sup>2</sup>=25,
1700 7<sup>2</sup>=49, etc. </p>
1702 <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
1703 positive and negative results are relative to a user-specified bias value.
1704 This is important for non-HDRI compilations of ImageMagick when dealing with
1705 convolutions that contain negative as well as positive values. This is
1706 especially the case with convolutions involving high pass filters or edge
1707 detection. Without an output bias, the negative values is clipped at zero.
1710 <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
1711 negative results without clipping to the color value range (0..QuantumRange).
1712 See the discussion on HDRI implementations of ImageMagick on the page <a
1713 href="high-dynamic-range.html">High
1714 Dynamic-Range Images</a>. For more about HDRI go the ImageMagick <a
1715 href="http://www.imagemagick.org/Usage/basics/#hdri">Usage</a> pages or this
1716 <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">Wikipedia</a>
1720 <div style="margin: auto;">
1721 <h4><a id="crop"></a>-crop <em class="arg">geometry</em></h4>
1724 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Cut out one or more rectangular regions of the image.</td><td style='text-align:right;'></td></tr></table>
1726 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
1728 <p>The <em class="arg">width</em> and <em class="arg">height</em> of the <em
1729 class="arg">geometry</em> argument give the size of the image that remains
1730 after cropping, and <em class="arg">x</em> and <em class="arg">y</em> in the
1731 <em class="arg">offset</em> (if present) gives the location of the top left
1732 corner of the cropped image with respect to the original image. To specify the
1733 amount to be removed, use <a href="command-line-options.html#shave">-shave</a> instead.</p>
1735 <p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are
1736 present, a single image is generated, consisting of the pixels from the
1737 cropping region. The offsets specify the location of the upper left corner of
1738 the cropping region measured downward and rightward with respect to the upper
1739 left corner of the image. If the <a href="command-line-options.html#gravity">-gravity</a> option is
1740 present with <kbd>NorthEast</kbd>, <kbd>East</kbd>, or <kbd>SouthEast</kbd>
1741 gravity, it gives the distance leftward from the right edge of the image to
1742 the right edge of the cropping region. Similarly, if the <a
1743 href="command-line-options.html#gravity">-gravity</a> option is present with <kbd>SouthWest</kbd>,
1744 <kbd>South</kbd>, or <kbd>SouthEast</kbd> gravity, the distance is measured
1745 upward between the bottom edges.</p>
1747 <p>If the <em class="arg">x</em> and <em class="arg">y</em> offsets are
1748 omitted, a set of tiles of the specified geometry, covering the entire input
1749 image, is generated. The rightmost tiles and the bottom tiles are smaller if
1750 the specified geometry extends beyond the dimensions of the input image.</p>
1752 <p>By adding a exclamation character flag to the geometry argument, the
1753 cropped images virtual canvas page size and offset is set as if the
1754 geometry argument was a viewport or window. This means the canvas page size
1755 is set to exactly the same size you specified, the image offset set
1756 relative top left corner of the region cropped. </p>
1758 <p>If the cropped image 'missed' the actual image on its virtual canvas, a
1759 special single pixel transparent 'missed' image is returned, and a 'crop
1760 missed' warning given. </p>
1762 <p>It might be necessary to <a href="command-line-options.html#repage" >+repage</a> the image prior to
1763 cropping the image to ensure the crop coordinate frame is relocated to the
1764 upper-left corner of the visible image.
1766 Similarly you may want to use <a href="command-line-options.html#repage" >+repage</a> after cropping to
1767 remove the page offset that will be left behind. This is especially true when
1768 you are going to write to an image format such as PNG that supports an image
1771 <div style="margin: auto;">
1772 <h4><a id="cycle"></a>-cycle <em class="arg">amount</em></h4>
1775 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>displace image colormap by amount.</td><td style='text-align:right;'></td></tr></table>
1777 <p><em class="arg">Amount</em> defines the number of positions each
1778 colormap entry is shifted.</p>
1781 <div style="margin: auto;">
1782 <h4><a id="debug"></a>-debug <em class="arg">events</em></h4>
1785 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>enable debug printout.</td><td style='text-align:right;'></td></tr></table>
1787 <p>The <kbd>events</kbd> parameter specifies which events are to be logged. It
1788 can be either <kbd>None</kbd>, <kbd>All</kbd>, <kbd>Trace</kbd>, or
1789 a comma-separated list consisting of one or more of the following domains:
1790 <kbd>Accelerate</kbd>, <kbd>Annotate</kbd>, <kbd>Blob</kbd>, <kbd>Cache</kbd>,
1791 <kbd>Coder</kbd>, <kbd>Configure</kbd>, <kbd>Deprecate</kbd>,
1792 <kbd>Exception</kbd>, <kbd>Locale</kbd>, <kbd>Render</kbd>,
1793 <kbd>Resource</kbd>, <kbd>Security</kbd>, <kbd>TemporaryFile</kbd>,
1794 <kbd>Transform</kbd>, <kbd>X11</kbd>, or <kbd>User</kbd>. </p>
1797 <p>For example, to log cache and blob events, use.</p>
1799 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -debug "Cache,Blob" rose: rose.png</span></p>
1800 <p>The <kbd>User</kbd> domain is normally empty, but developers can log user
1801 events in their private copy of ImageMagick.</p>
1803 <p>To print the complete list of debug methods, use <a href="command-line-options.html#list">-list
1806 <p>Use the <a href="command-line-options.html#log">-log</a> option to specify the format for debugging
1809 <p>Use <a href="command-line-options.html#debug">+debug</a> to turn off all logging.</p>
1811 <p>Debugging may also be set using the <kbd>MAGICK_DEBUG</kbd> <a href="resources.html#environment"
1812 >environment variable</a>. The allowed values for the <kbd>MAGICK_DEBUG</kbd>
1813 environment variable are the same as for the <a href="command-line-options.html#debug">-debug</a>
1817 <div style="margin: auto;">
1818 <h4><a id="decipher"></a>-decipher <em class="arg">filename</em></h4>
1821 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Decipher and restore pixels that were previously transformed by
1822 <a href="command-line-options.html#encipher">-encipher</a>.</td><td style='text-align:right;'></td></tr></table>
1824 <p>Get the passphrase from the file specified by <em
1825 class="arg">filename</em>.</p>
1827 <p>For more information, see the webpage, <a
1828 href="../www/cipher.html">ImageMagick: Encipher or
1829 Decipher an Image</a>.</p>
1832 <div style="margin: auto;">
1833 <h4><a id="deconstruct"></a>-deconstruct</h4>
1836 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>find areas that has changed between images </td><td style='text-align:right;'></td></tr></table>
1838 <p>Given a sequence of images all the same size, such as produced by <a
1839 href="command-line-options.html#coalesce">-coalesce</a>, replace the second and later images, with
1840 a smaller image of just the area that changed relative to the previous image.
1843 <p>The resulting sequence of images can be used to optimize an animation
1844 sequence, though will not work correctly for GIF animations when parts of the
1845 animation can go from opaque to transparent. </p>
1847 <p>This option is actually equivalent to the <a href="command-line-options.html#layers">-layers</a>
1848 method '<kbd>compare-any</kbd>'. </p>
1851 <div style="margin: auto;">
1852 <h4><a id="define"></a>-define <em class="arg">key</em>{<em class="arg">=value</em>}<em class="arg">...</em></h4>
1855 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>add specific global settings generally used to control
1856 coders and image processing operations.</td><td style='text-align:right;'></td></tr></table>
1858 <p>This option creates one or more definitions for coders and decoders to use
1859 while reading and writing image data. Definitions are generally used to
1860 control image file format coder modules, and image processing operations,
1861 beyond what is provided by normal means. Defined settings are listed in <a
1862 href="command-line-options.html#verbose" >-verbose</a> information ("<kbd>info:</kbd>" output format)
1863 as "Artifacts". </p>
1865 <p>If <em class="arg">value</em> is missing for a definition, an empty-valued
1866 definition of a flag is created with that name. This used to control on/off
1867 options. Use <a href="command-line-options.html#define">+define key</a> to remove definitions
1868 previously created. Use <a href="command-line-options.html#define">+define "*"</a> to remove all
1869 existing definitions.</p>
1871 <p>The same 'artifact' settings can also be defined using the <a
1872 href="command-line-options.html#set" >-set "option:<em class="arg">key</em>" "<em class="arg"
1873 >value</em>"</a> option, which also allows the use of <a href="escape.html" >Format and Print Image
1874 Properties</a> in the defined value. </p>
1876 <p>The <em>option</em> and <em>key</em> are case-independent (they are
1877 converted to lowercase for use within the decoders) while the <em>value</em>
1878 is case-dependent.</p>
1880 <p>Such settings are global in scope, and effect all images and operations. </p>
1882 <p>The following definitions are just some of the artifacts that are
1887 <dt>compose:args=<em class="arg">arguments</em></dt>
1888 <dd>Sets certain compose argument values when using convert ... -compose ...
1889 -composite. See <a href="compose.html"
1890 >Image Composition</a></dd>
1892 <dt>distort:scale=<em class="arg">value</em></dt>
1893 <dd>Sets the output scaling factor for use with <a href="command-line-options.html#distort"
1896 <dt>distort:viewport=WxH+X+Y</dt>
1897 <dd>Sets the viewport for use with <a href="command-line-options.html#distort">-distort</a></dd>
1899 <dt>dcm:display-range=reset</dt>
1900 <dd>Set the display range to the minimum and maximum pixel values for the
1901 DCM image format.</dd>
1903 <dt>dot:layout-engine=<em class="arg">value</em></dt>
1904 <dd>Set the specify the layout engine for the DOT image format (e.g.
1905 <kbd>neato</kbd>).</dd>
1907 <dt>jpeg:extent=<em class="arg">value</em></dt>
1908 <dd>Restrict the maximum JPEG file size, for example <kbd>-define
1909 jpeg:extent=400kb</kbd>.</dd>
1911 <dt>jpeg:size=<em class="arg">geometry</em></dt>
1912 <dd>Set the size hint of a JPEG image, for example, -define jpeg:size=128x128.
1913 It is most useful for increasing performance and reducing the memory
1914 requirements when reducing the size of a large JPEG image.</dd>
1916 <dt>jp2:rate=<em class="arg">value</em></dt>
1917 <dd>Specify the compression factor to use while writing JPEG-2000 files. The
1918 compression factor is the reciprocal of the compression ratio. The valid
1919 range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined,
1920 this value overrides the -quality setting. A quality setting of 75
1921 results in a rate value of 0.06641.</dd>
1923 <dt>mng:need-cacheoff</dt>
1924 <dd>turn playback caching off for streaming MNG.</dd>
1926 <dt>png:bit-depth=<em class="arg">value</em></dt>
1927 <dt>png:color-type=<em class="arg">value</em></dt>
1928 <dd>desired bit-depth and color-type for PNG output. You can force the PNG
1929 encoder to use a different bit-depth and color-type than it would have
1930 normally selected, but only if this does not cause any loss of image
1931 quality. Any attempt to reduce image quality is treated as an error and no
1932 PNG file is written. E.g., if you have a 1-bit black-and-white image, you
1933 can use these "defines" to cause it to be written as an 8-bit grayscale,
1934 indexed, or even a 64-bit RGBA. But if you have a 16-million color image,
1935 you cannot force it to be written as a grayscale or indexed PNG. If you
1936 wish to do this, you must use the appropriate <a href="command-line-options.html#depth">-depth</a>,
1937 <a href="command-line-options.html#colors">-colors</a>, or <a href="command-line-options.html#type">-type</a> directives to
1938 reduce the image quality prior to using the PNG encoder. Note that in
1939 indexed PNG files, "bit-depth" refers to the number of bits per index,
1940 which can be 1, 2, 4, or 8. In such files, the color samples always have
1943 <dt>png:compression-filter=<em class="arg">value</em></dt>
1944 <dd> valid values are 0 through 7. 0-4 are the corresponding PNG filters,
1945 5 means adaptive filtering except for images with a colormap, 6 means
1946 adaptive filtering for all images, 7 means MNG "loco" compression.</dd>
1948 <dt>png:compression-level=<em class="arg">value</em></dt>
1949 <dd> valid values are 0 through 9, with 0 providing the least but fastest
1950 compression and 9 usually providing the best and always the slowest.</dd>
1952 <dt>png:compression-strategy=<em class="arg">value</em></dt>
1953 <dd> valid values are 0 through 4, meaning default, filtered, huffman_only,
1954 rle, and fixed ZLIB compression strategy. If you are using an old zlib
1955 that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2),
1956 values 3 and 4, respectively, will use the zlib default strategy
1959 <dt>png:format=<em class="arg">value</em></dt>
1960 <dd> valid values are <em class="arg">png8</em>, <em class="arg">png24</em>,
1961 and <em class="arg">png32</em>. This property can be useful for specifying
1962 the specific PNG format to be used, when the usual method of prepending the
1963 format name to the output filename is inconvenient, such as when writing
1964 a PNG-encoded ICO file.</dd>
1966 <dt>png:exclude-chunk=<em class="arg">value</em></dt>
1967 <dt>png:include-chunk=<em class="arg">value</em></dt>
1968 <dd>ancillary chunks to be excluded from or included in PNG output.
1970 <p>The<em class="arg">value</em> can be the name of a PNG chunk-type such
1971 as <em class="arg">bKGD</em>, a comma-separated list of chunk-types,
1972 or the word <em class="arg">all</em> or
1973 the word <em class="arg">none</em>. There must be no spaces in the
1974 list. Although PNG chunk-names are case-dependent, you can use
1975 all lowercase names if you prefer.</p>
1977 <p>The "include-chunk" and "exclude-chunk" lists only affect the behavior
1978 of the PNG encoder and have no effect on the PNG decoder.</p>
1980 <p>As a special case, if the <kbd>sRGB</kbd> chunk is excluded and
1981 the <kbd>gAMA</kbd> chunk is included, the <kbd>gAMA</kbd> chunk will
1982 only be written if gamma is not 1/2.2, since most decoders assume
1983 sRGB and gamma=1/2.2 when no colorspace information is included in
1984 the PNG file. Because the list is processed from left to right, you
1985 can achieve this with a single define:</p>
1988 -define png:include-chunk=none,gAMA
1991 <p>As a special case, if the <kbd>sRGB</kbd> chunk is not excluded and
1992 the PNG encoder recognizes that the image contains the sRGB ICC profile,
1993 the PNG encoder will write the <kbd>sRGB</kbd> chunk instead of the entire
1994 3144-byte ICC profile. To force the PNG encoder to write the sRGB
1995 profile as an <kbd>iCCP</kbd> chunk in the output PNG instead of the
1996 <kbd>sRGB</kbd> chunk, exclude the <kbd>sRGB</kbd> chunk.</p>
1998 <p>The critical PNG chunks <kbd>IHDR</kbd>, <kbd>PLTE</kbd>,
1999 <kbd>IDAT</kbd>, and <kbd>IEND</kbd> cannot be excluded. Any such
2000 entries appearing in the list will be ignored.</p>
2002 <p>If the ancillary PNG <kbd>tRNS</kbd> chunk is excluded and the
2003 image has transparency, the PNG colortype is forced to be 4 or 6
2004 (GRAY_ALPHA or RGBA). If the image is not transparent, then the
2005 <kbd>tRNS</kbd> chunk isn't written anyhow, and there is no effect
2006 on the PNG colortype of the output image.</p>
2008 <p>The <a href="command-line-options.html#strip">-strip</a> option does the equivalent of the
2009 following for PNG output:</p>
2012 -define png:include-chunk=none,trns,gama
2015 <p>The default behavior is to include all known PNG ancillary chunks
2016 plus ImageMagick's private <kbd>vpAg</kbd> ("virtual page") chunk,
2017 and to exclude all PNG chunks that are unknown to ImageMagick,
2018 regardless of their PNG "copy-safe" status as described in the
2019 PNG specification.</p>
2021 <p>Any chunk names that are not known to ImageMagick are ignored
2022 if they appear in either the "include-chunk" or "exclude-chunk" list.
2023 The ancillary chunks currently known to ImageMagick are
2024 <kbd>bKGD</kbd>, <kbd>cHRM</kbd>, <kbd>gAMA</kbd>, <kbd>iCCP</kbd>,
2025 <kbd>oFFs</kbd>, <kbd>pHYs</kbd>, <kbd>sRGB</kbd>, <kbd>tEXt</kbd>,
2026 <kbd>tRNS</kbd>, <kbd>vpAg</kbd>, and <kbd>zTXt</kbd>.</p>
2028 <p>You can also put <kbd>date</kbd> in the list to include or exclude
2029 the "Date:create" and "Date:modify" text chunks that ImageMagick normally
2030 inserts in the output PNG.</p>
2034 <dt>png:preserve-colormap</dt>
2035 <dd>Use the existing image->colormap. Normally the PNG encoder will
2036 try to optimize the palette, eliminating unused entries and putting
2037 the transparent colors first. If this flag is set, that behavior
2040 <dt>ps:imagemask</dt>
2041 <dd>If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create
2042 Postscript files that render bilevel images with the Postscript imagemask
2043 operator instead of the image operator.</dd>
2045 <dt>quantum:format=<em class="arg">type</em></dt>
2046 <dd>Set the type to <kbd>floating-point</kbd> to specify a floating-point
2047 format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode
2048 to preserve negative values. If <a href="command-line-options.html#depth">-depth</a> 16 is
2049 included, the result is a single precision floating point format.
2050 If <a href="command-line-options.html#depth">-depth</a> 32 is included, the result is
2051 double precision floating point format.</dd>
2053 <dt>showkernel=1</em></dt>
2054 <dd>Outputs (to 'standard error') all the information about a generated <a
2055 href="command-line-options.html#morphology" >-morphology</a> kernel.</dd>
2057 <dt>tiff:quantum:polarity=min-is-black
2059 tiff:quantum:polarity=min-is-white</dt>
2060 <dd>Toggles the photometric interpretation</dd>
2062 <dt>tiff:rows-per-strip=<em class="arg">value</em></dt>
2063 <dd>Sets the number of rows per strip</dd>
2065 <dt>tiff:tile-geometry=<em class="arg">WxH</em></dt>
2066 <dd>Sets the tile size for pyramid tiffs. Requires the suffix PTIF: before the
2072 <p>For example, to create a postscript file that will render only the black
2073 pixels of a bilevel image, use:</p>
2075 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert bilevel.tif -define ps:imagemask eps3:stencil.ps</span></p>
2076 <p>Set attributes of the image registry by prefixing the value with
2077 <kbd>registry:</kbd>. For example, to set a temporary path to put work files,
2081 -define registry:temporary-path=/data/tmp
2086 <div style="margin: auto;">
2087 <h4><a id="delay"></a>-delay <em class="arg">ticks</em> <br />-delay <em class="arg">ticks</em>x<em class="arg">ticks-per-second</em> {<em class="arg"><</em>} {<em class="arg">></em>}</h4>
2090 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>display the next image after pausing.</td><td style='text-align:right;'></td></tr></table>
2092 <p>This option is useful for regulating the animation of image sequences
2093 <em>ticks/ticks-per-second</em> seconds must expire before the display of the
2094 next image. The default is no delay between each showing of the image
2095 sequence. The default ticks-per-second is 100.</p>
2097 <p>Use <kbd>></kbd> to change the image delay <em>only</em> if its current
2098 value exceeds the given delay. <kbd><</kbd> changes the image delay
2099 <em>only</em> if current value is less than the given delay. For example, if
2100 you specify <kbd>30></kbd> and the image delay is 20, the image delay does
2101 not change. However, if the image delay is 40 or 50, the delay it is changed
2102 to 30. Enclose the given delay in quotation marks to prevent the
2103 <kbd><</kbd> or <kbd>></kbd> from being interpreted by your shell as
2104 a file redirection.</p>
2107 <div style="margin: auto;">
2108 <h4><a id="delete"></a>-delete <em class="arg">indexes</em></h4>
2111 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>delete the images specified by index, from the image sequence.</td><td style='text-align:right;'></td></tr></table>
2113 <p>Specify the image by its index in the sequence. The first image is index
2114 0. Negative indexes are relative to the end of the sequence, for example, -1
2115 represents the last image of the sequence. Specify a range of images with
2116 a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use
2117 <kbd>+delete</kbd> to delete the last image in the current image sequence.</p>
2120 <div style="margin: auto;">
2121 <h4><a id="density"></a>-density <em class="arg">width</em><br />-density <em class="arg">width</em>x<em class="arg">height</em></h4>
2124 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the horizontal and vertical resolution of an image for
2125 rendering to devices.</td><td style='text-align:right;'></td></tr></table>
2127 <p>This option specifies the image resolution to store while encoding a raster
2128 image or the canvas resolution while rendering (reading) vector formats such
2129 as Postscript, PDF, WMF, and SVG into a raster image. Image resolution
2130 provides the unit of measure to apply when rendering to an output device or
2131 raster image. The default unit of measure is in dots per inch (DPI). The <a
2132 href="command-line-options.html#units">-units</a> option may be used to select dots per centimeter
2135 <p>The default resolution is 72 dots per inch, which is equivalent to one
2136 point per pixel (Macintosh and Postscript standard). Computer screens are
2137 normally 72 or 96 dots per inch, while printers typically support 150, 300,
2138 600, or 1200 dots per inch. To determine the resolution of your display, use
2139 a ruler to measure the width of your screen in inches, and divide by the
2140 number of horizontal pixels (1024 on a 1024x768 display).</p>
2142 <p>If the file format supports it, this option may be used to update the
2143 stored image resolution. Note that Photoshop stores and obtains image
2144 resolution from a proprietary embedded profile. If this profile is not
2145 stripped from the image, then Photoshop will continue to treat the image using
2146 its former resolution, ignoring the image resolution specified in the standard
2149 <p>The <a href="command-line-options.html#density">-density</a> option sets an <em>attribute</em> and
2150 does not alter the underlying raster image. It may be used to adjust the
2151 rendered size for desktop publishing purposes by adjusting the scale applied
2152 to the pixels. To resize the image so that it is the same size at a different
2153 resolution, use the <a href="command-line-options.html#resample">-resample</a> option.</p>
2155 <div style="margin: auto;">
2156 <h4><a id="depth"></a>-depth <em class="arg">value</em></h4>
2159 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>depth of the image.</td><td style='text-align:right;'></td></tr></table>
2161 <p>This the number of bits in a color sample within a pixel. Use this option
2162 to specify the depth of raw images whose depth is unknown such as GRAY, RGB,
2163 or CMYK, or to change the depth of any image after it has been read.</p>
2165 <div style="margin: auto;">
2166 <h4><a id="descend"></a>-descend</h4>
2169 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>obtain image by descending window hierarchy.</td><td style='text-align:right;'></td></tr></table>
2171 <div style="margin: auto;">
2172 <h4><a id="deskew"></a>-deskew <em class="arg">threshold</em></h4>
2175 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>straighten an image. A threshold of 40% works for most images.</td><td style='text-align:right;'></td></tr></table>
2177 <p>Use <a href="command-line-options.html#set">-set</a> <kbd>option:deskew:auto-crop
2178 <em>width</em></kbd> to auto crop the image. The set argument is the pixel
2179 width of the image background (e.g 40).</p>
2181 <div style="margin: auto;">
2182 <h4><a id="despeckle"></a>-despeckle</h4>
2185 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce the speckles within an image.</td><td style='text-align:right;'></td></tr></table>
2187 <div style="margin: auto;">
2188 <h4><a id="direction"></a>-direction <em class="arg">type</em></h4>
2191 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>render text right-to-left or left-to-right.</td><td style='text-align:right;'></td></tr></table>
2193 <div style="margin: auto;">
2194 <h4><a id="displace"></a>-displace <em class="arg">horizontal-scale</em><br />-displace <em class="arg">horizontal-scale</em>x<em class="arg">vertical-scale</em></h4>
2197 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>shift image pixels as defined by a displacement map.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
2199 <p>With this option, the 'overlay' image, and optionally the 'mask' image,
2200 is used as a displacement map, which is used to displace the lookup of
2201 what part of the 'background' image is seen at each point of the overlaid
2202 area. Much like the displacement map is a 'lens' that redirects light shining
2203 through it so as to present a distorted view the original 'background' image
2206 <p>Any perfect grey areas of the displacement map produce a zero
2207 displacement of the image. Black areas produce the given maximum negative
2208 displacement of the lookup point, while white produce a maximum positive
2209 displacement of the lookup. </p>
2211 <p>Note that it is the lookup of the 'background' that is displaced, not a
2212 displacement of the image itself. As such an area of the displacement map
2213 containing 'white' will have the lookup point 'shifted' by a positive amount,
2214 and thus generating a copy of the destination image to the right/downward from
2215 the correct position. That is the image will look like it may have been
2216 'shifted' in a negative left/upward direction. Understanding this is a very
2217 important in understanding how displacement maps work. </p>
2219 <p>The given arguments define the maximum amount of displacement in pixels
2220 that a particular map can produce. If the displacement scale is large enough
2221 it is also possible to lookup parts of the 'background' image that lie well
2222 outside the bounds of the displacement map itself. That is you could very
2223 easily copy a section of the original image from outside the overlay area
2224 into the overlay area. </p>
2226 <p>The '%' flag makes the displacement scale relative to the size of the
2227 overlay image (100% = half width/height of image). Using '!' switches
2228 percentage arguments to refer to the destination image size instead.
2229 these flags were added as of IM v6.5.3-5.</p>
2231 <p>Normally a single grayscale displacement map is provided, which with the
2232 given scaling values will determine a single direction (vector) in which
2233 displacements can occur (positively or negatively). However, if you also
2234 specify a third image which is normally used as a <em class="arg">mask</em>,
2235 the <em class="arg">composite image</em> is used for horizontal X
2236 displacement, while the <em class="arg">mask image</em> is used for vertical Y
2237 displacement. This allows you to define completely different displacement
2238 values for the X and Y directions, and allowing you to lookup any point within
2239 the <em class="arg">scale</em> bounds. In other words each pixel can lookup
2240 any other nearby pixel, producing complex 2 dimensional displacements, rather
2241 than a simple 1 dimensional vector displacements. </p>
2243 <p>Alternatively rather than supplying two separate images, as of IM v6.4.4-0,
2244 you can use the 'red' channel of the overlay image to specify the horizontal
2245 or X displacement, and the 'green' channel for the vertical or Y displacement.
2248 <p>As of IM v6.5.3-5 any alpha channel in the overlay image is used as a
2249 mask the transparency of the destination image. However areas outside the
2250 overlaid areas will not be effected. </p>
2253 <div style="margin: auto;">
2254 <h4><a id="display"></a>-display <em class="arg">host:display[.screen]</em></h4>
2257 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specifies the X server to contact.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
2259 <p>This option is used with convert for obtaining image or font from this
2260 X server. See <em class="arg">X(1)</em>.</p>
2262 <div style="margin: auto;">
2263 <h4><a id="dispose"></a>-dispose <em class="arg">method</em></h4>
2266 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>define the GIF disposal image setting for images that are being created or read in. </td><td style='text-align:right;'></td></tr></table>
2268 <p>The layer disposal method defines the way each the displayed image is to be
2269 modified after the current 'frame' of an animation has finished being
2270 displayed (after its 'delay' period), but before the next frame on an
2271 animation is to be overlaid onto the display. </p>
2273 <p>Here are the valid methods:</p>
2276 Undefined 0 No disposal specified (equivalent to '<kbd>none</kbd>').
2277 None 1 Do not dispose, just overlay next frame image.
2278 Background 2 Clear the frame area with the background color.
2279 Previous 3 Clear to the image prior to this frames overlay.
2282 <p>You can also use the numbers given above, which is what the GIF format
2283 uses internally to represent the above settings. </p>
2285 <p>To print a complete list of dispose methods, use <a href="command-line-options.html#list">-list dispose</a>.</p>
2287 <p>Use <a href="command-line-options.html#dispose" >+dispose</a>, turn off the setting and prevent
2288 resetting the layer disposal methods of images being read in. </p>
2290 <p>Use <a href="command-line-options.html#set">-set</a> '<kbd>dispose</kbd>' method to set the image
2291 disposal method for images already in memory.</p>
2293 <div style="margin: auto;">
2294 <h4><a id="dissimilarity-threshold"></a>-dissimilarity-threshold <em class="arg">value</em></h4>
2297 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>maximum RMSE for subimage match (default 0.2).</td><td style='text-align:right;'>[<a href="compare.html">compare</a>]</td></tr></table>
2300 <div style="margin: auto;">
2301 <h4><a id="dissolve"></a>-dissolve <em class="arg">src_percent</em>[x<em class="arg">dst_percent</em>]</h4>
2304 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>dissolve an image into another by the given percent.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
2306 <p>The opacity of the composite image is multiplied by the given percent, then
2307 it is composited 'over' the main image. If <em class="arg">src_percent</em>
2308 is greater than 100, start dissolving the main image so it becomes
2309 transparent at a value of '<kbd class="arg">200</kbd>'. If both percentages
2310 are given, each image are dissolved to the percentages given. </p>
2312 <p>Note that dissolve percentages do not add, two opaque images dissolved
2313 '50,50', produce a 75% transparency. For a 50% + 50% blending of the two
2314 images, you would need to use dissolve values of '50,100'. </p>
2316 <div style="margin: auto;">
2317 <h4><a id="distort"></a>-distort <em class="arg">method arguments</em></h4>
2320 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>distort an image, using the given <em class="arg">method</em> and its required <em class="arg">arguments</em>.</td><td style='text-align:right;'></td></tr></table>
2322 <p>The <em class="arg">arguments</em> is a single string containing a list
2323 of floating point numbers separated by commas or spaces. The number of
2324 and meaning of the floating point values depends on the distortion <em
2325 class="arg">method</em> being used. </p>
2327 <p>Choose from these distortion types:</p>
2331 <th align="left" style="width: 8%">Method</th>
2332 <th align="left">Description</th>
2336 <td valign="top"><kbd>ScaleRotateTranslate</kbd>
2337 <br/>or <kbd>SRT</kbd></td>
2339 Distort image by first scaling and rotating about a given 'center',
2340 before translating that 'center' to the new location, in that order. It
2341 is an alternative method of specifying a '<kbd>Affine</kbd>' type of
2342 distortion, but without shearing effects. It also provides a good way
2343 of rotating and displacing a smaller image for tiling onto a larger
2344 background (IE 2-dimensional animations). <br/>
2346 The number of arguments determine the specific meaning of each
2347 argument for the scales, rotation, and translation operations. <br/>
2349 <table style="margin-left:auto; margin-right:auto;">
2350 <tr><td># </td><td>arguments meaning</td></tr>
2351 <tr><td>1:</td><td><em>Angle_of_Rotation</em></td></tr>
2352 <tr><td>2:</td><td><em>Scale Angle</em></td></tr>
2353 <tr><td>3:</td><td><em>X,Y Angle</em></td></tr>
2354 <tr><td>4:</td><td><em>X,Y Scale Angle</em></td></tr>
2356 <td><em>X,Y ScaleX,ScaleY Angle</em></td></tr>
2358 <td><em>X,Y Scale Angle NewX,NewY</em></td></tr>
2360 <td><em>X,Y ScaleX,ScaleY Angle
2361 NewX,NewY</em></td></tr>
2364 This is actually an alternative way of specifying a 2 dimensional linear
2365 '<kbd>Affine</kbd>' or '<kbd>AffineProjection</kbd>' distortion. </td> </tr>
2368 <td valign="top"><kbd>Affine</kbd></td>
2370 Distort the image linearly by moving a list of at least 3 or more sets
2371 of control points (as defined below). Ideally 3 sets or 12 floating
2372 point values are given allowing the image to be linearly scaled,
2373 rotated, sheared, and translated, according to those three points. See
2374 also the related '<kbd>AffineProjection</kbd>' and '<kbd>SRT</kbd>'
2377 More than 3 sets given control point pairs (12 numbers) is least
2378 squares fitted to best match a linear affine distortion. If only 2
2379 control point pairs (8 numbers) are given a two point image translation
2380 rotation and scaling is performed, without any possible shearing,
2381 flipping or changes in aspect ratio to the resulting image. If only one
2382 control point pair is provides the image is only translated, (which may
2383 be a floating point non-integer translation). <br/>
2385 This distortion does not include any form of perspective distortion.
2391 <td valign="top"><kbd>AffineProjection</kbd></td>
2393 Linearly distort an image using the given Affine Matrix of 6
2394 pre-calculated coefficients forming a set of Affine Equations to map
2395 the source image to the destination image.
2397 <div style="text-align: center"><em>
2398 s<sub>x</sub>, r<sub>x</sub>,
2399 r<sub>y</sub>, s<sub>y</sub>,
2400 t<sub>x</sub>, t<sub>y</sub>
2403 See <a href="command-line-options.html#affine" >-affine</a> setting for more detail, and
2404 meanings of these coefficients. <br/>
2406 The distortions '<kbd>Affine</kbd>' and '<kbd>SRT</kbd>' provide
2407 alternative methods of defining this distortion, with ImageMagick doing
2408 the calculations needed to generate the required coefficients. You can
2409 see the internally generated coefficients, by using a <a
2410 href="command-line-options.html#verbose" >-verbose</a> setting with those other variants. </td>
2415 <td valign="top"><kbd>BilinearForward</kbd><br/>
2416 <kbd>BilinearReverse</kbd></td>
2418 Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or
2419 16 values (see below). Not that lines may not appear straight after
2420 distortion, though the distance between coordinates will remain
2423 The '<kbd>BilinearForward</kbd>' is used to map rectangles to any
2424 quadrilateral, while the '<kbd>BilinearReverse</kbd>' form maps any
2425 quadrilateral to a rectangle, while preserving the straight line edges
2428 Note that '<kbd>BilinearForward</kbd>' can generate invalid pixels
2429 which will be colored using the <a href="command-line-options.html#mattecolor" >-mattecolor</a>
2430 color setting. Also if the quadrilateral becomes 'flipped' the image
2431 may disappear. <br/>
2433 There are future plans to produce a true Bilinear distortion that will
2434 attempt to map any quadrilateral to any other quadrilateral, while
2435 preserving edges (and edge distance ratios).
2441 <td valign="top"><kbd>Perspective</kbd></td>
2443 Perspective distort the images, using a list of 4 or more sets of
2444 control points (as defined below). More that 4 sets (16 numbers) of
2445 control points provide least squares fitting for more accurate
2446 distortions (for the purposes of image registration and panorama
2447 effects). Less than 4 sets will fall back to a '<kbd>Affine</kbd>'
2448 linear distortion. <br/>
2450 Perspective Distorted images ensures that straight lines remain
2451 straight, but the scale of the distorted image will vary. The horizon
2452 is anti-aliased, and the 'sky' color may be set using the
2453 <a href="command-line-options.html#mattecolor" >-mattecolor</a> setting. </td>
2457 <td valign="top"><kbd>PerspectiveProjection</kbd> </td>
2459 Do a '<kbd>Perspective</kbd>' distortion biased on a set of 8
2460 pre-calculated coefficients. You can get these coefficients by looking
2461 at the <a href="command-line-options.html#verbose" >-verbose</a> output of a
2462 '<kbd>Perspective</kbd>' distortion, or by calculating them yourself.
2463 If the last two perspective scaling coefficients are zero, the
2464 remaining 6 represents a transposed 'Affine Matrix'. </td>
2469 <td valign="top"><kbd>Arc</kbd></td>
2471 Arc the image (variation of polar mapping) over the angle given around
2473 <table width="90%" style = "margin-left: auto; margin-right: auto;">
2474 <tr valign="top"><td>Argument</td>
2475 <td>Meaning</td></tr>
2476 <tr valign="top"><td><em>arc_angle</em></td>
2477 <td>The angle over which to arc the image side-to-side</td></tr>
2478 <tr valign="top"><td><em>rotate_angle</em></td>
2479 <td>Angle to rotate resulting image from vertical center</td></tr>
2480 <tr valign="top"><td><em>top_radius</em></td>
2481 <td>Set top edge of source image at this radius</td></tr>
2482 <tr valign="top"><td><em>bottom_radius</em> </td>
2483 <td>Set bottom edge to this radius (radial scaling)</td></tr>
2486 The resulting image is always resized to best fit the resulting image,
2487 (as if using <a href="command-line-options.html#distort" >+distort</a>) while attempting to
2488 preserve scale and aspect ratio of the original image as much as
2489 possible with the arguments given by the user. All four arguments will
2490 be needed to change the overall aspect ratio of an 'Arc'ed image. <br/>
2492 This a variation of a polar distortion designed to try to preserve the
2493 aspect ratio of the image rather than direct Cartesian to Polar
2498 <td valign="top"><kbd>Polar</kbd></td>
2500 Like '<kbd>Arc</kbd>' but do a complete Cartesian to Polar mapping of
2501 the image. that is the height of the input image is mapped to the
2502 radius limits, while the width is wrapped around between the
2505 Arguments: <em>Rmax,Rmin CenterX,CenterY, start,end_angle</em> <br/>
2507 All arguments are optional. With <em>Rmin</em> defaulting to zero, the
2508 center to the center of the image, and the angles going from -180 (top)
2509 to +180 (top). If <em>Rmax</em> is given the special value of
2510 '<code>0</code>', the the distance from the center to the nearest edge
2511 is used for the radius of the output image, which will ensure the whole
2512 image is visible (though scaled smaller). However a special value of
2513 '<code>-1</code>' will use the distance from the center to the furthest
2514 corner, This may 'clip' the corners from the input rectangular image,
2515 but will generate the exact reverse of a '<kbd>DePolar</kbd>' with
2516 the same arguments. <br/>
2518 If the plus form of distort (<a href="command-line-options.html#distort" >+distort</a>) is used
2519 output image center will default to <code>0,0</code> of the virtual
2520 canvas, and the image size adjusted to ensure the whole input image is
2521 made visible in the output image on the virtual canvas. </td>
2526 <td valign="top"><kbd>DePolar</kbd></td>
2528 Uses the same arguments and meanings as a '<kbd>Polar</kbd>' distortion
2529 but generates the reverse Polar to Cartesian distortion. <br/>
2531 The special <em>Rmax</em> setting of '<code>0</code>' may however clip
2532 the corners of the input image. However using the special
2533 <em>Rmax</em> setting of '<code>-1</code>' (maximum center to corner
2534 distance) will ensure the whole distorted image is preserved in the
2535 generated result, so that the same argument to '<kbd>Polar</kbd>' will
2536 reverse the distortion re-producing the original.
2538 Note that as this distortion requires the area resampling of a circular
2539 arc, which can not be handled by the builtin EWA resampling function.
2540 As such the normal EWA filters are turned off. It is recommended some
2541 form of 'super-sampling' image processing technique be used to produce
2542 a high quality result. </td>
2547 <td valign="top"><kbd>Barrel</kbd></td>
2549 Given the four coefficients (A,B,C,D) as defined by <a
2550 href="http://wiki.panotools.org/Lens_correction_model" >Helmut
2551 Dersch</a>, perform a barrel or pin-cushion distortion appropriate to
2552 correct radial lens distortions. That is in photographs, make straight
2553 lines straight again. <br/>
2555 Arguments: <em>A B C</em> [ <em>D</em> [
2556 <em>X</em> , <em>Y</em> ] ] <br/>
2557 or <em>A<sub>x</sub> B<sub>x</sub> C<sub>x</sub> D<sub>x</sub>
2558 A<sub>y</sub> B<sub>y</sub> C<sub>y</sub> D<sub>y</sub></em>
2559 [ <em>X</em> , <em>Y</em> ] <br/>
2560 So that it forms the function <br/>
2561 Rsrc = r * ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> +
2562 <em>C</em>*r + <em>D</em> )<br/>
2564 Where <em>X</em>,<em>Y</em> is the optional center of the distortion
2565 (defaulting to the center of the image). <br/>
2566 The second form is typically used to distort images, rather than
2567 correct lens distortions. <br/>
2573 <td valign="top"><kbd>BarrelInverse</kbd></td>
2575 This is very similar to '<kbd>Barrel</kbd>' with the same set of
2576 arguments, and argument handling. However it uses the inverse
2577 of the radial polynomial,
2578 so that it forms the function <br/>
2579 Rsrc = r / ( <em>A</em>*r<sup>3</sup> + <em>B</em>*r<sup>2</sup> +
2580 <em>C</em>*r + <em>D</em> )<br/>
2581 Note that this is not the reverse of the '<kbd>Barrel</kbd>'
2582 distortion, just a different barrel-like radial distortion method.
2588 <td valign="top"><kbd>Shepards</kbd></td>
2590 Distort the given list control points (any number) using an Inverse
2591 Squared Distance Interpolation Method (<a
2592 href="http://en.wikipedia.org/wiki/Shepard%27s_method" >Shepards
2593 Method</a>). The control points in effect do 'localized' displacement
2594 of the image around the given control point (preserving the look and
2595 the rotation of the area near the control points. For best results
2596 extra control points should be added to 'lock' the positions of the
2597 corners, edges and other unchanging parts of the image, to prevent
2598 their movement. <br/>
2600 The distortion has been likened to 'taffy pulling' using nails, or
2601 pins' stuck in a block of 'jelly' which is then moved to the new
2602 position, distorting the surface of the jelly. <br/>
2604 Internally it is equivalent to generating a displacement map (see <a
2605 href="command-line-options.html#displace" >-displace</a>) for source image color look-up using
2606 the <a href="command-line-options.html#sparse-color" >-sparse-color</a> method of the same name.
2613 <p>To print a complete list of distortion methods, use <a href="command-line-options.html#list">-list
2616 <p>Many of the above distortion methods such as '<kbd>Affine</kbd>',
2617 '<kbd>Perspective</kbd>', and '<kbd>Shepards</kbd>' use a list control points
2618 defining how these points in the given image should be distorted in the
2619 destination image. Each set of four floating point values represent a source
2620 image coordinate, followed immediately by the destination image coordinate.
2621 This produces a list of values such as...</p>
2622 <div style="text-align: center"><em>
2623 U<sub>1</sub>,V<sub>1</sub> X<sub>1</sub>,Y<sub>1</sub>
2624 U<sub>2</sub>,V<sub>2</sub> X<sub>2</sub>,Y<sub>2</sub>
2625 U<sub>3</sub>,V<sub>3</sub> X<sub>3</sub>,Y<sub>3</sub>
2627 U<sub>n</sub>,V<sub>n</sub> X<sub>n</sub>,Y<sub>n</sub>
2629 <p>where <em>U,V</em> on the source image is mapped to <em>X,Y</em> on the
2630 destination image. </p>
2632 <p>For example, to warp an image using '<kbd>perspective</kbd>' distortion,
2633 needs a list of at least 4 sets of coordinates, or 16 numbers. Here is the
2634 perspective distortion of the built-in "rose:" image. Note how spaces were
2635 used to group the 4 sets of coordinate pairs, to make it easier to read and
2638 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>
2639 convert rose: -virtual-pixel black \<br/>
2640 -distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \<br/>
2641 rose_3d_rotated.gif</span></p>
2642 <p>If more that the required number of coordinate pairs are given for
2643 a distortion, the distortion method is 'least squares' fitted to produce the
2644 best result for all the coordinate pairs given. If less than the ideal number
2645 of points are given, the distort will generally fall back to a simpler form of
2646 distortion that can handles the smaller number of coordinates (usually a linear
2647 '<kbd>Affine</kbd>' distortion). </p>
2649 <p>By using more coordinates you can make use of image registration tool to
2650 find matching coordinate pairs in overlapping images, so as to improve the
2651 'fit' of the distortion. Of course a bad coordinate pair can also make the
2652 'fit' worse. Caution is always advised. </p>
2654 <p>Colors are acquired from the source image according to the <a
2655 href="command-line-options.html#interpolate" >-interpolate</a> color lookup setting, when the image is
2656 magnified. However if the viewed image is minified (image becomes smaller),
2657 a special area resampling function (added ImageMagick v6.3.5-9), is used to
2658 produce a higher quality image. For example you can use
2659 a '<kbd>perspective</kbd>' distortion to view a infinitely tiled 'plane' all
2660 the way to the horizon. </p>
2662 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>
2663 convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \<br/>
2664 -distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \<br/>
2665 checks_tiled.jpg</span></p>
2666 <p>Note that a infinitely tiled perspective images involving the horizon can
2667 be very slow to generate due to the use of the high quality 'area resampling'
2668 function (added ImageMagick v6.3.5-9). You can turn off 'area resampling'
2669 using a <a href="command-line-options.html#filter" >-filter</a> setting of '<kbd>point</kbd>'
2670 (recommended if you plan to use super-sampling instead). </p>
2672 <p>If an image generates <i>invalid pixels</i>, such as the 'sky' in the last
2673 '<kbd>perspective</kbd>' distortion example, <a href="command-line-options.html#distort" >-distort</a>
2674 will use the current <a href="command-line-options.html#mattecolor" >-mattecolor</a> setting for these
2675 pixels. If you do not what these pixels to be visible, set the color to match
2676 the rest of the ground. </p>
2678 <p>The output image size will by default be the same as the input image. This
2679 means that if the part of the distorted image falls outside the viewed area of
2680 the 'distorted space', those parts is clipped and lost. However if you use
2681 the plus form of the operator (<a href="command-line-options.html#distort" >+distort</a>) the operator
2682 will attempt (if possible) to show the whole of the distorted image, while
2683 retaining a correct 'virtual canvas' offset, for image layering. This offset
2684 may need to be removed using <a href="command-line-options.html#repage" >+repage</a>, to remove if it
2687 <p>You can alternatively specify a special "<kbd><a href="command-line-options.html#set" >-set</a>
2688 option:distort:viewport {geometry_string}</kbd>" setting which will specify
2689 the size and the offset of the generated 'viewport' image of the distorted
2692 <p>Adding a "<kbd><a href="command-line-options.html#set" >-set</a> option:distort:scale
2693 {scale_factor}</kbd>" will scale the output image (viewport or otherwise) by
2694 that factor without changing the viewed contents of the distorted image. This
2695 can be used either for 'super-sampling' the image for a higher quality result,
2696 or for panning and zooming around the image (with appropriate viewport
2697 changes, or post-distort cropping and resizing). </p>
2699 <p>Setting <a href="command-line-options.html#verbose" >-verbose</a> setting, will cause <a
2700 href="command-line-options.html#distort" >-distort</a> to attempt to output the internal coefficients,
2701 and the <a href="command-line-options.html#fx" >-fx</a> equivalent to the distortion, for expert study,
2702 and debugging purposes. This many not be available for all distorts. </p>
2704 <p>Affine rotations and shears (such as '<kbd>SRT</kbd>' distortion), tend to
2705 produce a cleaner result that the equivalent <a href="command-line-options.html#rotate" >-rotate</a>
2706 and/or <a href="command-line-options.html#shear" >-shear</a> operation, with more control of due to the
2707 above settings. It is algorithmically slower however, though that may not be
2708 the case in ImageMagick's implementation. </p>
2711 <div style="margin: auto;">
2712 <h4><a id="dither"></a>-dither <em class="arg">method</em></h4>
2715 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a Riemersma or Floyd-Steinberg error diffusion dither to
2716 images when general color reduction is applied via an option, or automagically
2717 when saving to specific formats. This enabled by default. </td><td style='text-align:right;'></td></tr></table>
2719 <p>Dithering places two or more colors in neighboring pixels so that to the
2720 eye a closer approximation of the images original color is reproduced. This
2721 reduces the number of colors needed to reproduce the image but at the cost of
2722 a lower level pattern of colors. Error diffusion dithers can use any set of
2723 colors (generated or user defined) to an image. </p>
2725 <p>Dithering is turned on by default, to turn it off use the plus form of the
2726 setting, <a href="command-line-options.html#dither">+dither</a>. This will also also render PostScript
2727 without text or graphic aliasing. Disabling dithering often (but not always)
2728 leads to faster process, a smaller number of colors, but more cartoon like
2729 image coloring. Generally resulting in 'color banding' effects in areas with
2730 color gradients. </p>
2732 <p>The color reduction operators <a href="command-line-options.html#colors">-colors</a>, <a
2733 href="command-line-options.html#monochrome">-monochrome</a>, <a href="command-line-options.html#remap ">-remap</a>, and <a
2734 href="command-line-options.html#posterize">-posterize</a>, apply dithering to images using the reduced
2735 color set they created. These operators are also used as part of automatic
2736 color reduction when saving images to formats with limited color support, such
2737 as <kbd>GIF:</kbd>, <kbd>XBM:</kbd>, and others, so dithering may also be used
2738 in these cases. </p>
2740 <p>Alternatively you can use <a href="command-line-options.html#random-threshold">-random-threshold</a>
2741 to generate purely random dither. Or use <a
2742 href="command-line-options.html#ordered-dither">-ordered-dither</a> to apply threshold mapped dither
2743 patterns, using uniform color maps, rather than specific color maps. </p>
2746 <div style="margin: auto;">
2747 <h4><a id="draw"></a>-draw <em class="arg">string</em></h4>
2750 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Annotate an image with one or more graphic primitives.</td><td style='text-align:right;'></td></tr></table>
2752 <p>Use this option to annotate or decorate an image with one or more graphic
2753 primitives. The primitives include shapes, text, transformations, and pixel
2756 <p>The shape primitives:</p>
2761 rectangle x0,y0 x1,y1
2762 roundRectangle x0,y0 x1,y1 wc,hc
2763 arc x0,y0 x1,y1 a0,a1
2764 ellipse x0,y0 rx,ry a0,a1
2766 polyline x0,y0 ... xn,yn
2767 polygon x0,y0 ... xn,yn
2768 bezier x0,y0 ... xn,yn
2769 path path specification
2770 image operator x0,y0 w,h filename
2773 <p>The text primitive:</p>
2778 <p>The text gravity primitive:</p>
2781 gravity NorthWest, North, NorthEast, West, Center,
2782 East, SouthWest, South, or SouthEast
2785 <p>The text gravity primitive only affects the placement of text and does not
2786 interact with the other primitives. It is equivalent to using the <a
2787 href="command-line-options.html#gravity">-gravity</a> command-line option, except that it is limited in
2788 scope to the <a href="command-line-options.html#draw">-draw</a> option in which it appears.</p>
2790 <p>The transformation primitives:</p>
2800 <p>The pixel operation primitives:</p>
2807 <p>The shape primitives are drawn in the color specified by the preceding <a
2808 href="command-line-options.html#fill">-fill</a> setting. For unfilled shapes, use <a
2809 href="command-line-options.html#fill">-fill none</a>. You can optionally control the stroke (the
2810 "outline" of a shape) with the <a href="command-line-options.html#stroke">-stroke</a> and <a
2811 href="command-line-options.html#strokewidth">-strokewidth</a> settings.</p>
2813 <p>A <kbd>point</kbd> primitive is specified by a single <em>point</em> in the
2814 pixel plane, that is, by an ordered pair of integer coordinates,
2815 <em>x</em>,<em>y</em>. (As it involves only a single pixel, a <kbd>point</kbd>
2816 primitive is not affected by <a href="command-line-options.html#stroke">-stroke</a> or <a
2817 href="command-line-options.html#strokewidth">-strokewidth</a>.)</p>
2819 <p>A <kbd>line</kbd> primitive requires a start point and end point.</p>
2821 <p>A <kbd>rectangle</kbd> primitive is specified by the pair of points at the
2822 upper left and lower right corners.</p>
2824 <p>A <kbd>roundRectangle</kbd> primitive takes the same corner points as
2825 a <kbd>rectangle</kbd> followed by the width and height of the rounded corners
2828 <p>The <kbd>circle</kbd> primitive makes a disk (filled) or circle (unfilled).
2829 Give the center and any point on the perimeter (boundary).</p>
2831 <p>The <kbd>arc</kbd> primitive is used to inscribe an elliptical segment in
2832 to a given rectangle. An <kbd>arc</kbd> requires the two corners used for
2833 <kbd>rectangle</kbd> (see above) followed by the start and end angles of the
2834 arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end
2835 points produced are then joined with a line segment and the resulting segment
2836 of an ellipse is filled.</p>
2838 <p>Use <kbd>ellipse</kbd> to draw a partial (or whole) ellipse. Give the
2839 center point, the horizontal and vertical "radii" (the <em>semi-axes</em> of
2840 the ellipse) and start and end angles in degrees (e.g. 100,100 100,150
2843 <p>The <kbd>polyline</kbd> and <kbd>polygon</kbd> primitives require three or
2844 more points to define their perimeters. A <kbd>polyline</kbd> is simply
2845 a <kbd>polygon</kbd> in which the final point is not stroked to the start
2846 point. When unfilled, this is a <em>polygonal line</em>. If the <a
2847 href="command-line-options.html#stroke">-stroke</a> setting is <kbd>none</kbd> (the default), then
2848 a <kbd>polyline</kbd> is identical to a <kbd>polygon</kbd>. </p>
2850 <p>A <em>coordinate</em> is a pair of integers separated by a space or
2851 optional comma. </p>
2853 <p>As an example, to define a circle centered at 100,100 that extends to
2857 -draw 'circle 100,100 150,150'
2860 <p>The <kbd>Bezier</kbd> primitive creates a spline curve and requires three
2861 or points to define its shape. The first and last points are the
2862 <em>knots</em> and these points are attained by the curve, while any
2863 intermediate coordinates are <em>control points</em>. If two control points
2864 are specified, the line between each end knot and its sequentially respective
2865 control point determines the tangent direction of the curve at that end. If
2866 one control point is specified, the lines from the end knots to the one
2867 control point determines the tangent directions of the curve at each end. If
2868 more than two control points are specified, then the additional control points
2869 act in combination to determine the intermediate shape of the curve. In order
2870 to draw complex curves, it is highly recommended either to use the
2871 <kbd>path</kbd> primitive or to draw multiple four-point bezier segments with
2872 the start and end knots of each successive segment repeated. For example:</p>
2875 -draw 'bezier 20,50 45,100 45,0 70,50'
2878 -draw 'bezier 70,50 95,100 95,0 120,50'
2882 <p>A <kbd>path</kbd> represents an outline of an object, defined in terms of
2883 moveto (set a new current point), lineto (draw a straight line), curveto (draw
2884 a Bezier curve), arc (elliptical or circular arc) and closepath (close the
2885 current shape by drawing a line to the last moveto) elements. Compound paths
2886 (i.e., a path with subpaths, each consisting of a single moveto followed by
2887 one or more line or curve operations) are possible to allow effects such as
2888 <em>donut holes</em> in objects. (See <a
2889 href="http://www.w3.org/TR/SVG/paths.html">Paths</a>.)</p>
2891 <p>Use <kbd>image</kbd> to composite an image with another image. Follow the
2892 image keyword with the composite operator, image location, image size, and
2896 -draw 'image SrcOver 100,100 225,225 image.jpg'
2899 <p>You can use 0,0 for the image size, which means to use the actual
2900 dimensions found in the image header. Otherwise, it is scaled to the given
2901 dimensions. See <a href="compose.html">Alpha Compositing</a> for
2902 a detailed discussion of alpha composition methods that are available. </p>
2904 The "special augmented compose operators" such as "dissolve" that require
2905 arguments cannot be used at present with the <kbd>-draw image</kbd> option.
2908 <p>Use <kbd>text</kbd> to annotate an image with text. Follow the text
2909 coordinates with a string. If the string has embedded spaces, enclose it in
2910 single or double quotes.</p>
2912 <p>For example, the following annotates the image with <kbd>Works like
2913 magick!</kbd> for an image titled <kbd>bird.miff</kbd>. </p>
2916 -draw "text 100,100 'Works like magick!' "
2919 <p>See the <a href="command-line-options.html#annotate">-annotate</a> option for another convenient way
2920 to annotate an image with text.</p>
2922 <p>The <kbd>rotate</kbd> primitive rotates subsequent shape primitives and
2923 text primitives about the origin of the main image. If the <a
2924 href="command-line-options.html#region">-region</a> option precedes the <a href="command-line-options.html#draw">-draw</a>
2925 option, the origin for transformations is the upper left corner of the
2928 <p>The <kbd>translate</kbd> primitive translates subsequent shape and text
2931 <p>The <kbd>scale</kbd> primitive scales them.</p>
2933 <p>The <kbd>skewX</kbd> and <kbd>skewY</kbd> primitives skew them with respect
2934 to the origin of the main image or the region.</p>
2936 <p>The transformations modify the current affine matrix, which is initialized
2937 from the initial affine matrix defined by the <a href="command-line-options.html#affine">-affine</a>
2938 option. Transformations are cumulative within the <a href="command-line-options.html#draw">-draw</a>
2939 option. The initial affine matrix is not affected; that matrix is only changed
2940 by the appearance of another <a href="command-line-options.html#affine">-affine</a> option. If another
2941 <a href="command-line-options.html#draw">-draw</a> option appears, the current affine matrix is
2942 reinitialized from the initial affine matrix.</p>
2944 <p>Use the <kbd>color</kbd> primitive to change the color of a pixel to the
2945 fill color (see <a href="command-line-options.html#fill">-fill</a>). Follow the pixel coordinate with
2956 <p>Consider the target pixel as that specified by your coordinate. The
2957 <kbd>point</kbd> method recolors the target pixel. The <kbd>replace</kbd>
2958 method recolors any pixel that matches the color of the target pixel.
2959 <kbd>Floodfill</kbd> recolors any pixel that matches the color of the target
2960 pixel and is a neighbor, whereas <kbd>filltoborder</kbd> recolors any neighbor
2961 pixel that is not the border color. Finally, <kbd>reset</kbd> recolors all
2964 <p>Use <kbd>matte</kbd> to the change the pixel matte value to transparent.
2965 Follow the pixel coordinate with a method (see the <kbd>color</kbd> primitive
2966 for a description of methods). The <kbd>point</kbd> method changes the matte
2967 value of the target pixel. The <kbd>replace</kbd> method changes the matte
2968 value of any pixel that matches the color of the target pixel.
2969 <kbd>Floodfill</kbd> changes the matte value of any pixel that matches the
2970 color of the target pixel and is a neighbor, whereas <kbd>filltoborder</kbd>
2971 changes the matte value of any neighbor pixel that is not the border color (<a
2972 href="command-line-options.html#bordercolor">-bordercolor</a>). Finally <kbd>reset</kbd> changes the
2973 matte value of all pixels.</p>
2975 <p>You can set the primitive color, font, and font bounding box color with <a
2976 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>
2977 respectively. Options are processed in command line order so be sure to use
2978 these options <em>before</em> the <a href="command-line-options.html#draw">-draw</a> option.</p>
2980 <p>Strings that begin with a number must be quoted (e.g. use '1.png' rather
2983 <p>Drawing primitives conform to the <a href="magick-vector-graphics.html" >Magick
2984 Vector Graphics</a> format.</p>
2987 <div style="margin: auto;">
2988 <h4><a id="duplicate"></a>-duplicate <em class="arg">count,indexes</em></h4>
2991 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>duplicate an image one or more times.</td><td style='text-align:right;'></td></tr></table>
2993 <p>Specify the count and the image to duplicate by its index in the sequence.
2994 The first image is index 0. Negative indexes are relative to the end of the
2995 sequence, for example, -1 represents the last image of the sequence. Specify
2996 a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g.
2997 0,2). Use <kbd>+duplicate</kbd> to duplicate the last image in the current
3000 <div style="margin: auto;">
3001 <h4><a id="edge"></a>-edge <em class="arg">radius</em></h4>
3004 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>detect edges within an image.</td><td style='text-align:right;'></td></tr></table>
3006 <div style="margin: auto;">
3007 <h4><a id="emboss"></a>-emboss <em class="arg">radius</em></h4>
3010 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>emboss an image.</td><td style='text-align:right;'></td></tr></table>
3012 <div style="margin: auto;">
3013 <h4><a id="encipher"></a>-encipher <em class="arg">filename</em></h4>
3016 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Encipher pixels for later deciphering by <a href="command-line-options.html#decipher">-decipher</a>.</td><td style='text-align:right;'></td></tr></table>
3018 <p>Get the passphrase from the file specified by <em class="arg"
3021 <p>For more information, see the webpage, <a
3022 href="../www/cipher.html">ImageMagick: Encipher or
3023 Decipher an Image</a>.</p>
3027 <div style="margin: auto;">
3028 <h4><a id="encoding"></a>-encoding <em class="arg">type</em></h4>
3031 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the text encoding.</td><td style='text-align:right;'></td></tr></table>
3033 <p>Choose from <kbd>AdobeCustom</kbd>, <kbd>AdobeExpert</kbd>,
3034 <kbd>AdobeStandard</kbd>, <kbd>AppleRoman</kbd>, <kbd>BIG5</kbd>,
3035 <kbd>GB2312</kbd>, <kbd>Latin 2</kbd>, <kbd>None</kbd>, <kbd>SJIScode</kbd>,
3036 <kbd>Symbol</kbd>, <kbd>Unicode</kbd>, <kbd>Wansung</kbd>.</p>
3038 <div style="margin: auto;">
3039 <h4><a id="endian"></a>-endian <em class="arg">type</em></h4>
3042 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify endianness (<kbd>MSB</kbd> or <kbd>LSB</kbd>) of the image.</td><td style='text-align:right;'></td></tr></table>
3044 <p>To print a complete list of endian types, use the <a href="command-line-options.html#list">-list endian</a> option.</p>
3046 <p>Use <a href="command-line-options.html#endian">+endian</a> to revert to unspecified endianness.</p>
3049 <div style="margin: auto;">
3050 <h4><a id="enhance"></a>-enhance</h4>
3053 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a digital filter to enhance a noisy image.</td><td style='text-align:right;'></td></tr></table>
3056 <div style="margin: auto;">
3057 <h4><a id="equalize"></a>-equalize</h4>
3060 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform histogram equalization on the image channel-by-channel.</td><td style='text-align:right;'></td></tr></table>
3062 <p>To perform histogram equalization on all channels in concert, transform the
3063 image into some other color space, such as HSL, OHTA, YIQ or YUV, then
3064 equalize the appropriate intensity-like channel, then convert back to RGB.</p>
3066 <p>For example using HSL, we have: ... <kbd>-colorspace HSL -channel lightness
3067 -equalize -colorspace RGB</kbd> ...</p>
3069 <p>For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal
3070 components transformation that puts most of the information in the first
3071 channel. Here we have ... <kbd>-colorspace OHTA -channel red -equalize
3072 -colorspace RGB</kbd> ...</p>
3074 <div style="margin: auto;">
3075 <h4><a id="evaluate"></a>-evaluate <em class="arg">operator value</em></h4>
3078 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Alter channel pixels by evaluating an arithmetic, relational, or logical expression.</td><td style='text-align:right;'></td></tr></table>
3080 <p>(See the <a href="command-line-options.html#function" >-function</a> operator for some
3081 multi-parameter functions. See the <a href="command-line-options.html#fx" >-fx</a> operator if more
3082 elaborate calculations are needed.)</p>
3084 <p>The behaviors of each <em class="arg">operator</em> are summarized in the
3085 following list. For brevity, the numerical value of a "pixel" referred to
3086 below is the value of the corresponding channel of that pixel, while
3087 a "normalized pixel" is that number divided by the maximum
3088 (installation-dependent) value <em class="QR">QuantumRange</em>. (If
3089 normalized pixels are used, they are restored, following the other
3090 calculations, to the full range by multiplying by <em
3091 class="QR">QuantumRange</em>.)</p>
3098 <th><em class="arg">operator</em></th>
3099 <th>Summary (see further below for details)</th>
3104 <tr><td>Abs </td> <td>Add <em class="arg">value</em> to pixels and return absolute value. </td></tr>
3105 <tr><td>Add </td> <td>Add <em class="arg">value</em> to pixels. </td></tr>
3106 <tr><td>AddModulus </td> <td>Add <em class="arg">value</em> to pixels modulo <em class="QR">QuantumRange</em>.</td></tr>
3107 <tr><td>And </td> <td>Binary AND of pixels with <em class="arg">value</em>.</td></tr>
3108 <tr><td>Cos, Cosine </td> <td>Apply cosine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr>
3109 <tr><td>Divide </td> <td>Divide pixels by <em class="arg">value</em>.</td></tr>
3110 <tr><td>Exp </td> <td>base-e exponential function</td></tr>
3111 <tr><td>Exponential </td> <td>base-e exponential function</td></tr>
3112 <tr><td>LeftShift </td> <td>Shift the pixel values left by <em class="arg">value</em> bits (i.e., multiply pixels by 2<sup><em class="arg">value</em></sup>).</td></tr>
3113 <tr><td>Log </td> <td>Apply scaled logarithm to normalized pixels.</td></tr>
3114 <tr><td>Max </td> <td>Clip pixels at lower bound <em class="arg">value</em>.</td></tr>
3115 <tr><td>Mean </td> <td>Add the <em class="arg">value</em> and divide by 2.</td></tr>
3116 <tr><td>Median </td> <td>Choose the median value from an image sequence.</td></tr>
3117 <tr><td>Min </td> <td>Clip pixels at upper bound <em class="arg">value</em>.</td></tr>
3118 <tr><td>Multiply </td> <td>Multiply pixels by <em class="arg">value</em>.</td></tr>
3119 <tr><td>Or </td> <td>Binary OR of pixels with <em class="arg">value</em>.</td></tr>
3120 <tr><td>Pow </td> <td>Raise normalized pixels to the power <em class="arg">value</em>.</td></tr>
3121 <tr><td>RightShift </td> <td>Shift the pixel values right by <em class="arg">value</em> bits (i.e., divide pixels by 2<sup><em class="arg">value</em></sup>).</td></tr>
3122 <tr><td>Set </td> <td>Set pixel equal to <em class="arg">value</em>.</td></tr>
3123 <tr><td>Sin, Sine </td> <td>Apply sine to pixels with frequency <em class="arg">value</em> with 50% bias added.</td></tr>
3124 <tr><td>Subtract </td> <td>Subtract <em class="arg">value</em> from pixels.</td></tr>
3125 <tr><td>Xor </td> <td>Binary XOR of pixels with <em class="arg">value.</em></td></tr>
3127 <tr><td> </td></tr>
3129 <tr><td>Gaussian-noise</td></tr>
3130 <tr><td>Impulse-noise</td></tr>
3131 <tr><td>Laplacian-noise</td></tr>
3132 <tr><td>Multiplicative-noise</td> <td>(These are equivalent to the corresponding <a href="command-line-options.html#noise" >-noise</a> operators.)</td></tr>
3133 <tr><td>PoissonNoise</td></tr>
3134 <tr><td>Uniform-noise</td></tr>
3136 <tr><td> </td></tr>
3138 <tr><td>Threshold </td> <td>Threshold pixels larger than <em class="arg">value</em>.</td></tr>
3139 <tr><td>ThresholdBlack </td> <td>Threshold pixels to zero values equal to or below <em class="arg">value</em>.</td></tr>
3140 <tr><td>ThresholdWhite </td> <td>Threshold pixels to maximum values above <em class="arg">value</em>. </td></tr>
3144 <p>The specified functions are applied only to each previously set <a
3145 href="command-line-options.html#channel" >-channel</a> in the image. If necessary, the results of the
3146 calculations are truncated (clipped) to fit in the interval [0, <em
3147 class="QR">QuantumRange</em>]. The transparency channel of the image is
3148 represented as a 'alpha' values (0 = fully transparent), so, for example, a
3149 <kbd>Divide</kbd> by 2 of the alpha channel will make the image
3150 semi-transparent. Append the percent symbol '<kbd>%</kbd>' to specify a value
3151 as a percentage of the <em class="QR">QuantumRange</em>.</p>
3153 <p>To print a complete list of <a href="command-line-options.html#evaluate">-evaluate</a> operators, use
3154 <a href="command-line-options.html#list">-list evaluate</a>.</p>
3156 <p>The results of the <kbd>Add</kbd>, <kbd>Subtract</kbd> and
3157 <kbd>Multiply</kbd> methods can also be achieved using either the <a
3158 href="command-line-options.html#level" >-level</a> or the <a href="command-line-options.html#level" >+level</a> operator, with
3159 appropriate argument, to linearly modify the overall range of color values.
3160 Please note, however, that <a href="command-line-options.html#level" >-level</a> treats transparency as
3161 'matte' values (0 = opaque), while <a href="command-line-options.html#level" >-evaluate</a> works with
3164 <p><kbd>AddModulus</kbd> has been added as of ImageMagick 6.4.8-4 and provides
3165 addition modulo the <em class="QR">QuantumRange</em>. It is therefore
3166 equivalent to <kbd>Add</kbd> unless the resulting pixel value is outside the
3167 interval [0, <em class="QR">QuantumRange</em>]. </p>
3169 <p><kbd>Exp or Exponential</kbd> has been added as of ImageMagick 6.6.5-1 and
3170 works on normalized pixel values. The <em class="arg">value</em> used with
3171 <kbd>Exp</kbd> should be negative so as to produce a decaying exponential
3172 function. Non-negative values will always produce results larger unity and
3173 thus outside the interval [0, <em class="QR">QuantumRange</em>]. The
3174 formula is expressed below. </p>
3176 <div style="text-align:center;">
3177 exp(<em class="arg">value</em> × <b><em>u</em></b>)
3180 <p> If the input image is squared, for example, using <a href="command-line-options.html#-function"
3181 >-function polynomial "2 0 0"</a>, then a decaying Gaussian function will be
3184 <p><kbd>Log</kbd> has been added as of ImageMagick 6.4.2-1 and works on
3185 normalized pixel values. This a <em>scaled</em> log function. The <em
3186 class="arg">value</em> used with <kbd>Log</kbd> provides a <em>scaling
3187 factor</em> that adjusts the curvature in the graph of the log function. The
3188 formula applied to a normalized value <b><em>u</em></b> is below. </p>
3190 <div style="text-align:center;">
3191 log(<em class="arg">value</em> × <b><em>u</em></b> + 1) / log(<em class="arg">value</em> + 1)
3194 <p><kbd>Pow</kbd> has been added as of ImageMagick 6.4.1-9, and works on
3195 normalized pixel values. Note that <kbd>Pow</kbd> is related to the <a
3196 href="command-line-options.html#gamma" >-gamma</a> operator. For example, <b>-gamma 2</b> is equivalent
3197 to <b>-evaluate pow 0.5</b>, i.e., a 'square root' function. The value used
3198 with <a href="command-line-options.html#gamma" >-gamma</a> is simply the reciprocal of the value used
3199 with <kbd>Pow</kbd>.</p>
3201 <p><kbd>Cosine</kbd> and <kbd>Sine</kbd> was added as of IM v6.4.8-8 and
3202 converts the image values into a value according to a (co)sine wave function.
3203 The synonyms <kbd>Cos</kbd> and <kbd>Sin</kbd> may also be used. The output
3204 is biased 50% and normalized by 50% so as to fit in the respective color value
3205 range. The <em class="arg">value</em> scaling of the <em>period</em> of the
3206 function (its frequency), and thus determines the number of 'waves' that will
3207 be generated over the input color range. For example, if the <em
3208 class="arg">value</em> is 1, the effective period is simply the <em
3209 class="QR">QuantumRange</em>; but if the <em class="arg">value</em> is 2,
3210 then the effective period is the <em>half</em> the <em
3211 class="QR">QuantumRange</em>.</p>
3213 <div style="text-align:center;">
3214 0.5 + 0.5 × cos(2 π <b><em>u</em></b> × <em class="arg">value</em>).
3217 <p>See also the <a href="command-line-options.html#function" >-function</a> operator, which is a
3218 multi-value version of evaluate. </p>
3220 <div style="margin: auto;">
3221 <h4><a id="evaluate-sequence"></a>-evaluate-sequence <em class="arg">operator</em></h4>
3224 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Alter channel pixels by evaluating an arithmetic, relational, or
3225 logical expression over a sequence of images.</td><td style='text-align:right;'></td></tr></table>
3227 <p>To print a complete list of <a
3228 href="command-line-options.html#evaluate-sequence">-evaluate-sequence</a> operators, use <a
3229 href="command-line-options.html#list">-list evaluate</a>.</p>
3231 <div style="margin: auto;">
3232 <h4><a id="extent"></a>-extent <em class="arg">geometry</em></h4>
3235 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the image size and offset.</td><td style='text-align:right;'></td></tr></table>
3237 <p>If the image is enlarged, unfilled areas are set to the background color.
3238 To position the image, use offsets in the <em class="arg">geometry</em>
3239 specification or precede with a <a href="command-line-options.html#gravity">-gravity</a> setting. To
3240 specify how to compose the image with the background, use <a href="command-line-options.html#compose"
3243 <p>This command reduces or expands a JPEG image to fit on an 800x600
3244 display. If the aspect ratio of the input image isn't exactly 4:3, then the
3245 image is centered on an 800x600 black canvas: </p>
3247 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert input.jpg -resize 800x600 -background black -compose Copy \ <br /> -gravity center -extent 800x600 -quality 92 output.jpg</span></p>
3250 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3252 <div style="margin: auto;">
3253 <h4><a id="extract"></a>-extract <em class="arg">geometry</em></h4>
3256 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Extract the specified area from image.</td><td style='text-align:right;'></td></tr></table>
3258 <p>This option is most useful for extracting a subregion of a very large raw
3259 image. Note that these two commands are equivalent:</p>
3261 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \ <br/> image.rgb image.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \ <br/> image.rgb image.png</span></p><p>If you omit the offsets, as in</p>
3263 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 -extract 640x480 \ <br/> image.rgb image.png</span></p>
3264 <p>the image is <em>resized</em> to the specified dimensions instead,
3267 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png</span></p>
3268 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
3270 <div style="margin: auto;">
3271 <h4><a id="family"></a>-family <em class="arg">fontFamily</em></h4>
3274 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font family for text.</td><td style='text-align:right;'></td></tr></table>
3276 <p>This setting suggests a font family that ImageMagick should try to use for
3277 rendering text. If the family can be found it is used; if not, a default font
3278 (e.g., "Arial") or a family known to be similar is substituted (e.g.,
3279 "Courier" might be used if "System" is requested but not found). </p>
3281 <p>For other settings that affect fonts, see the options <a
3282 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
3283 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3285 <div style="margin: auto;">
3286 <h4><a id="features"></a>-features <em class="arg">distance</em></h4>
3289 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>display features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance.</td><td style='text-align:right;'></td></tr></table>
3291 <div style="margin: auto;">
3292 <h4><a id="fft"></a>-fft</h4>
3295 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implements the forward discrete Fourier transform (DFT).</td><td style='text-align:right;'></td></tr></table>
3297 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
3298 users in ImageMagick 6.6.0-9). It transforms an image from the normal
3299 (spatial) domain to the frequency domain. In the frequency domain, an image is
3300 represented as a superposition of complex sinusoidal waves of varying
3301 amplitudes. The image x and y coordinates are the possible frequencies along
3302 the x and y directions, respectively, and the pixel intensity values are
3303 complex numbers that correspond to the sinusoidal wave amplitudes. See for
3304 example, <a href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier
3305 Transform</a>, <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier
3306 Transform</a> and <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier
3309 <p>A single image name is provided as output for this option. However, the
3310 output result will have two components. It is either a two-frame image or two
3311 separate images, depending upon whether the image format specified supports
3312 multi-frame images. The reason that we get a dual output result is because the
3313 frequency domain represents an image using complex numbers, which cannot be
3314 visualized directly. Therefore, the complex values are automagically separated
3315 into a two-component image representation. The first component is the
3316 magnitude of the complex number and the second is the phase of the complex
3317 number. See for example, <a
3318 href="http://en.wikipedia.org/wiki/Complex_numbers">Complex Numbers</a>.</p>
3320 <p>The magnitude and phase component images must be specified using image
3321 formats that do not limit the color or compress the image. Thus, MIFF, TIF,
3322 PFM, EXR and PNG are the recommended image formats to use. All of these
3323 formats, except PNG support multi-frame images. So for example,</p>
3325 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -fft fft_image.miff</span></p>
3326 <p>generates a magnitude image as <kbd>fft_image.miff[0]</kbd> and a phase
3327 image as <kbd>fft_image.miff[1]</kbd>. Similarly,</p>
3329 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -fft fft_image.png</span></p>
3330 <p>generates a magnitude image as <kbd>fft_image-0.png</kbd> and a phase image
3331 as <kbd>fft_image-1.png</kbd>. If you prefer this representation, then you can
3332 force any of the other formats to produce two output images by including <a
3333 href="command-line-options.html#adjoin">+adjoin</a> following -fft in the command line.</p>
3335 <p>The input image can be any size, but if not square and even-dimensioned, it
3336 is padded automagically to the larger of the width or height of the input
3337 image and to an even number of pixels. The padding will occur at the bottom
3338 and/or right sides of the input image. The resulting output magnitude and
3339 phase images is square at this size. The kind of padding relies on the <a
3340 href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting.</p>
3342 <p>Both output components will have dynamic ranges that fit within
3343 [0, <em class="QR">QuantumRange</em>], so that HDRI need not be enabled.
3344 Phase values nominally range from 0 to 2*π, but is scaled to span the full
3345 dynamic range. (The first few releases had non-HDRI scaled but HDRI not
3346 scaled). The magnitude image is not scaled and thus generally will contain
3347 very small values. As such, the image normally will appear totally black. In
3348 order to view any detail, the magnitude image typically is enhanced with a log
3349 function into what is usually called the spectrum. A log function is used to
3350 enhance the darker values more in comparison to the lighter values. This can
3351 be done, for example, as follows:</p>
3353 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert fft_image.miff[0] -contrast-stretch 0 \ <br />
3354 -evaluate log 1000 fft_image_spectrum.png</span></p>
3355 <p>where either <a href="command-line-options.html#contrast-stretch">-contrast-stretch</a> 0 or <a
3356 href="command-line-options.html#auto-level">-auto-level</a> is used to scale the image to full dynamic
3357 range, first. The argument to the <a href="command-line-options.html#evaluate">-evaluate</a> log
3358 typically is specified between 100 and 10,000, depending upon the amount of
3359 detail that one wants to bring out in the spectrum. Larger values produce more
3360 visible detail. Too much detail, however, may hide the important features.</p>
3362 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
3363 use <a href="command-line-options.html#fft">-fft</a>.</p>
3365 <p>Use <a href="command-line-options.html#fft">+fft</a> to produce two output images that are the real
3366 and imaginary components of the complex valued Fourier transform.</p>
3368 <p>However, as the real and imaginary components can contain negative values,
3369 this requires that IM be configured with HDRI enabled. In this case, you must
3370 use either MIFF, TIF, PFM or MPC formats for the real and imaginary component
3371 results, since they are formats that preserve both negative and fractional
3372 values without clipping them or truncating the fractional part. With either
3373 MIFF or TIF, one should add -define quantum:format=32, to allow those image
3374 types to work properly in HDRI mode without clipping.</p>
3376 <p>The real and imaginary component images resulting from <a
3377 href="command-line-options.html#fft">+fft</a> are also square, even dimensioned images due to the same
3378 padding that was discussed above for the magnitude and phase component
3381 <p>See the discussion on HDRI implementations of ImageMagick on the page <a
3382 href="high-dynamic-range.html" >High Dynamic-Range Images</a>. For more
3383 about HDRI go the ImageMagick <a
3384 href="http://www.imagemagick.org/Usage/basics/#hdri" >Usage</a> pages, <a
3385 href="http://www.fmwconcepts.com/imagemagick/fourier_transforms/fourier.html"
3386 >Fred's Fourier Processing With ImageMagick page</a> or this <a
3387 href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging" >Wikipedia</a>
3391 <div style="margin: auto;">
3392 <h4><a id="fill"></a>-fill <em class="arg">color</em></h4>
3395 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color to use when filling a graphic primitive.</td><td style='text-align:right;'></td></tr></table>
3397 <p>This option accepts a color name, a hex color, or a numerical RGB, RGBA,
3398 HSL, HSLA, CMYK, or CMYKA specification. See <a href="color.html" >Color Names</a> for
3399 a description of how to properly specify the color argument.</p>
3401 <p>Enclose the color specification in quotation marks to prevent the "#" or
3402 the parentheses from being interpreted by your shell.</p>
3413 -fill "rgb(255,255,255)"
3416 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
3418 <p>To print a complete list of color names, use the <a href="command-line-options.html#list">-list color</a> option.</p>
3420 <div style="margin: auto;">
3421 <h4><a id="filter"></a>-filter <em class="arg">type</em></h4>
3424 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Use this <em class="arg">type</em> of filter when resizing or
3425 distorting an image.</td><td style='text-align:right;'></td></tr></table>
3427 <p>Use this option to affect the resizing operation of an image during
3428 operations such as <a href="command-line-options.html#resize">-resize</a> and <a href="command-line-options.html#distort"
3429 >-distort</a>. For example you can use a simple resize filter such as:</p>
3434 Triangle Quadratic Mitchell
3437 <p>The <kbd>Bessel</kbd> and <kbd>Sinc</kbd> filter is also provided (as well
3438 as a faster <kbd>SincFast</kbd> equivalent form). However these filters are
3439 generally useless on their own as they are infinite filters that are being
3440 clipped to the filters support size. Their direct use is not recommended
3441 except via expert settings (see below). </p>
3443 <p>Instead these special filter functions are typically windowed by a windowing
3444 function that the <a href="command-line-options.html#filter" >-filter</a> setting defines. That is
3445 using these functions will define a 'Windowed' filter, appropriate to the
3446 operator involved. Windowed filters include: </p>
3449 Lanczos Hamming Parzen
3450 Blackman Kaiser Welsh
3451 Hanning Bartlett Bohman
3454 <p>Also one special self-windowing filter is also provided
3455 <kbd>Lagrange</kbd>, which will automagically re-adjust its function depending
3456 on the current 'support' or 'lobes' expert settings (see below).</p>
3458 <p>If you do not select a filter with this option, the filter defaults to
3459 <kbd>Mitchell</kbd> for a colormapped image, a image with a matte channel, or
3460 if the image is enlarged. Otherwise the filter default to
3461 <kbd>Lanczos</kbd>.</p>
3463 <p>To print a complete list of resize filters, use the <a href="command-line-options.html#list">-list
3464 filter</a> option.</p>
3466 <p>You can modify how the filter behaves as it scales your image through the
3467 use of these expert settings (see also <a href="command-line-options.html#define" >-define</a> and <a
3468 href="command-line-options.html#set" >-set</a>):-</p>
3471 <dt>-define filter:blur=<em>factor</em></dt>
3472 <dd>Scale the X axis of the filter (and its window). Use > 1.0 for
3473 blurry or < 1.0 for sharp. This should only be used with Gaussian and
3474 Gaussian-like filters simple filters, or you may not get the expected
3477 <dt>-define filter:support=<em>radius</em></dt>
3478 <dd>Set the filter support radius. Defines how large the filter should be and
3479 thus directly defines how slow the filtered resampling process is. All
3480 filters have a default 'prefered' support size. Some filters like
3481 <kbd>Lagrange</kbd> and windowed filters adjust themselves depending on
3482 this value. With simple filters this value either does nothing (but slow
3483 the resampling), or will clip the filter function in a detrimental way.
3486 <dt>-define filter:lobes=<em>count</em></dt>
3487 <dd>Set the number of lobes to use for the Sinc/Bessel filter. This an
3488 alternative way of specifying the 'support' range of the filter, that is
3489 designed to be more suited to windowed filters, especially when used for
3490 image distorts.</dd>
3492 <dt>-define filter:sigma=<em>value</em></dt>
3493 <dd>The 'sigma' value used to define the <kbd>Gaussian</kbd> filter. Default
3494 sigma value is '<kbd>0.5</kbd>'. It only effects <kbd>Gaussian</kbd> but
3495 does not shrink (but may enlarge) the filter's 'support'. It can be used
3496 to generate very small blurs but without the filter 'missing' pixels due
3497 to using a small support setting. A larger value of '<kbd>0.707</kbd>'
3498 (a value of '1/sqrt(2)') is another common setting. </dd>
3500 <dt>-define filter:b=<em>b-spline_factor</em></dt>
3501 <dt>-define filter:c=<em>keys_alpha_factor</em></dt>
3502 <dd>Redefine the values used for cubic filters such as <kbd>Cubic</kbd>,
3503 <kbd>Catrom</kbd>, <kbd>Mitchel</kbd>, and <kbd>Hermite</kbd>, as well as
3504 the <kbd>Parzen</kbd> cubic windowing function. If only one of the values
3505 are defined, the other is set so as to generate a 'Cubic-Keys' filter.
3506 The values meaning was defined by a research paper by
3507 Mitchell-Netravali.</dd>
3509 <dt>-define filter:kaiser-beta=<em>value</em></dt>
3510 <dd>The 'alpha' value used to as part of the Kaiser Windowing function.
3511 Default value is '6.5'. It only effects Kaiser windowing function, and
3512 does not effect any other attributes.</dd>
3514 <dd>Before IM v6.7.6-10, this option was known as "filter:alpha", (an
3515 inheritance from the very old "zoom" program). It was changed to bring the
3516 function in line with more modern academic research usage, and better
3517 assign it be more definitive. </dd>
3519 <dt>-define filter:kaiser-alpha=<em>value</em></dt>
3520 <dd>This value when multiplied by 'PI' is equivelent to "kaiser-beta", and
3521 will override that setting. It only effects Kaiser windowing function,
3522 and does not effect any other attributes. </dd>
3524 <dt>-define filter:filter=<em>filter_function</em></dt>
3525 <dd>Use this function directly as the weighting filter. This will allow
3526 you to directly use a windowing function such as <kbd>Blackman</kbd>,
3527 as a resampling filter, rather than as its normal usage as a windowing
3530 <dd>If defined, no windowing function also defined, the window function is set
3531 to <kbd>Box</kbd>). Directly specifying <kbd>Sinc</kbd> or <kbd>Jinc</kbd>
3532 as a filter will also do this. </dd>
3534 <dt>-define filter:window=<em>filter_function</em></dt>
3535 <dd>The IIR (infinite impulse response) filters <kbd>Sinc</kbd> and
3536 <kbd>Jinc</kbd> are windowed (brought down to zero over the defined
3537 support range) with the given filter. This allows you to specify a filter
3538 function to be used as a windowing function for these IIR filters. </dd>
3540 <dd>Many of the defined filters are actually windowing functions for these IIR
3541 filters. A typical choices is <kbd>Box</kbd>, (which effectively turns
3542 off the windowing function). </dd>
3544 <dt>-define filter:verbose=<em>1</em></dt>
3545 <dd>This causes IM to print information on the final internal filter
3546 selection to standard output. This includes a commented header on the
3547 filter settings being used, and data allowing the filter weights to be
3548 easily graphed. </dd>
3550 <dd>Note however that some filters are internally defined in terms of other
3551 filters. The <kbd>Lanczos</kbd> filter for example is defined in terms of
3552 a <kbd>SincFast</kbd> windowed <kbd>SincFast</kbd> filter, while
3553 <kbd>Mitchell</kbd> is defined as a <kbd>Cubic</kbd> filter with specific
3554 'B' and 'C' settings. </dd>
3558 <p>For example, to get a 8 lobe Bessel windowed Bessel filter:</p>
3560 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -filter bessel \<br/>
3561 -set filter:window=bessel -set filter:lobes=8 \<br/>
3562 -resize 150% image.jpg</span></p>
3563 <p>Or a raw un-windowed Sinc filter with 4 lobes:</p>
3565 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -set filter:filter=sinc -set filter:lobes=4 \<br/>
3566 -resize 150% image.jpg</span></p>
3567 <p>To extract the data for a raw windowing function, combine it with
3568 a '<kbd>Box</kbd>' filter. For example the '<kbd>Welsh</kbd> parabolic
3569 windowing function. </p>
3571 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert null: -define filter:filter=Box \<br/>
3572 -define filter:window=Welsh \<br/>
3573 -define filter:support=1.0 \<br/>
3574 -define filter:verbose=1 \<br/>
3575 -resize 2 null: > window_welsh.dat<br/>
3578 plot "window_welsh.dat" with lines</span></p>
3579 <p>Note that the use of expert options is provided for image processing experts
3580 who have studied and understand how resize filters work. Without this
3581 knowledge, and an understanding of the definition of the actual filters
3582 involved, using expert settings are more likely to be detrimental to your image
3586 <div style="margin: auto;">
3587 <h4><a id="flatten"></a>-flatten</h4>
3590 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>This is a simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "flatten".</td><td style='text-align:right;'></td></tr></table>
3593 <div style="margin: auto;">
3594 <h4><a id="flip"></a>-flip</h4>
3597 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>create a <em>mirror image</em>.</td><td style='text-align:right;'></td></tr></table>
3599 <p>reflect the scanlines in the vertical direction. The image will be mirrored
3603 <div style="margin: auto;">
3604 <h4><a id="floodfill"></a>-floodfill {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em> <em class="arg">color</em></h4>
3607 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>floodfill the image with color at the specified offset.</td><td style='text-align:right;'></td></tr></table>
3609 <p>Flood fill starts from the given 'seed point' which is not gravity effected.
3610 Any color that matches within <a href="command-line-options.html#fuzz" >-fuzz</a> color distance of the
3611 given <em class="arg">color</em> argument, connected to that 'seed point'
3612 will be replaced with the current <a href="command-line-options.html#fill" >-fill</a> color. </p>
3614 <p>Note that if the pixel at the 'seed point' does not itself match the given
3615 <em class="arg">color</em> (according to <a href="command-line-options.html#fuzz" >-fuzz</a>), then no
3616 action will be taken. </p>
3618 <p>This operator works more like the <a href="command-line-options.html#opaque" >-opaque</A> option, than
3619 a more general flood fill that reads the matching color directly at the 'seed
3620 point'. For this form of flood fill, look at <a href="command-line-options.html#draw" >-draw</a> and
3621 its 'color floodfill' drawing method. </p>
3624 <div style="margin: auto;">
3625 <h4><a id="flop"></a>-flop</h4>
3628 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>create a <em>mirror image</em>.</td><td style='text-align:right;'></td></tr></table>
3630 <p>Reflect the scanlines in the horizontal direction, just like the image in
3631 a vertical mirror. </p>
3634 <div style="margin: auto;">
3635 <h4><a id="font"></a>-font <em class="arg">name</em></h4>
3638 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the font to use when annotating images with text, or creating labels.</td><td style='text-align:right;'></td></tr></table>
3640 <p>To print a complete list of fonts, use the <a href="command-line-options.html#list">-list font</a>
3641 option (for versions prior to 6.3.6, use 'type' instead of 'font').</p>
3643 <p>In addition to the fonts specified by the above pre-defined list, you can
3644 also specify a font from a specific source. For example <kbd>Arial.ttf</kbd>
3645 is a TrueType font file, <kbd>ps:helvetica</kbd> is PostScript font, and
3646 <kbd>x:fixed</kbd> is X11 font.</p>
3648 <p>For other settings that affect fonts, see the options <a
3649 href="command-line-options.html#family">-family</a>, <a href="command-line-options.html#stretch">-stretch</a>, <a
3650 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
3653 <div style="margin: auto;">
3654 <h4><a id="foreground"></a>-foreground <em class="arg">color</em></h4>
3657 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Define the foreground color for menus.</td><td style='text-align:right;'>[<a href="display.html">display</a>]</td></tr></table>
3659 <p>The color is specified using the format described under the <a
3660 href="command-line-options.html#fill">-fill</a> option.</p>
3662 <p>The default foreground color is black.</p>
3664 <div style="margin: auto;">
3665 <h4><a id="format"></a>-format <em class="arg">type</em></h4>
3668 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the image format type.</td><td style='text-align:right;'></td></tr></table>
3670 <p>When used with the <kbd>mogrify</kbd> utility, this option converts any
3671 image to the image <a href="formats.html">format</a> you specify.
3672 For a list of image format types supported by ImageMagick, use <a
3673 href="command-line-options.html#list">-list format</a>.</p>
3675 <p>By default the file is written to its original name. However, if the
3676 filename extension matches a supported format, the extension is replaced with
3677 the image format type specified with <a href="command-line-options.html#format">-format</a>. For
3678 example, if you specify <em class="arg">tiff</em> as the format type and the
3679 input image filename is <em class="arg">image.gif</em>, the output image
3680 filename becomes <em class="arg">image.tiff</em>.</p>
3682 <div style="margin: auto;">
3683 <h4><a id="format_identify_"></a>-format <em class="arg">string</em></h4>
3686 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>output formatted image characteristics.</td><td style='text-align:right;'>[<a href="identify.html">identify</a>]</td></tr></table>
3688 <p>See <a href="escape.html">Format and Print Image
3689 Properties</a> for an explanation on how to specify the argument to this
3692 <div style="margin: auto;">
3693 <h4><a id="frame"></a>-frame <em class="arg">geometry</em></h4>
3696 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Surround the image with a border or beveled frame.</td><td style='text-align:right;'></td></tr></table>
3698 <p>The color of the border is specified with the <a href="command-line-options.html#mattecolor"
3699 >-mattecolor</a> command line option. </p>
3701 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument. The <em class="arg">size</em> portion of the <em
3702 class="arg">geometry</em> argument indicates the amount of extra width and
3703 height that is added to the dimensions of the image. If no offsets are given
3704 in the <em class="arg">geometry</em> argument, then the border added is
3705 a solid color. Offsets <em>x</em> and <em>y</em>, if present, specify that
3706 the width and height of the border is partitioned to form an outer bevel of
3707 thickness <em>x</em> pixels and an inner bevel of thickness
3708 <em>y</em> pixels. Negative offsets make no sense as frame arguments.
3711 <p>The <a href="command-line-options.html#frame">-frame</a> option is affected by the current <a
3712 href="command-line-options.html#compose">-compose</a> setting and assumes that this is using the default
3713 '<kbd>Over</kbd>' composition method. It generates a image of the appropriate
3714 size with the current <a href="command-line-options.html#bordercolor">-bordercolor</a> setting, and then
3715 draws the frame of four distinct colors close to the current <a
3716 href="command-line-options.html#mattecolor">-mattecolor</a>. The original image is then overlaid onto
3717 center of this image. This means that with the default compose method of
3718 '<kbd>Over</kbd>' any transparent parts may be replaced by the current <a
3719 href="command-line-options.html#bordercolor">-bordercolor</a> setting.</p>
3721 <p>The image composition is not
3722 affected by the <a href="command-line-options.html#gravity">-gravity</a> option.</p>
3725 <div style="margin: auto;">
3726 <h4><a id="frame_import_"></a>-frame</h4>
3729 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>include the X window frame in the imported image.</td><td style='text-align:right;'>[<a href="import.html">import</a>]</td></tr></table>
3731 <div style="margin: auto;">
3732 <h4><a id="function"></a>-function <em class="arg">function</em> <em class="arg">parameters</em></h4>
3735 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a function to channel values.</td><td style='text-align:right;'></td></tr></table>
3737 <p>This operator performs calculations based on the given arguments to modify
3738 each of the color values for each previously set <a
3739 href="command-line-options.html#channel">-channel</a> in the image. See <a
3740 href="command-line-options.html#evaluate">-evaluate</a> for details concerning how the results of the
3741 calculations are handled.</p>
3743 <p>This is can be considered a multi-argument version of the <a
3744 href="command-line-options.html#evaluate">-evaluate</a> operator. (Added in
3745 ImageMagick 6.4.8−8.)</p>
3747 <p>Here, <em class="arg">parameters</em> is a comma-separated list of
3748 numerical values. The number of values varies depending on which <em
3749 class="arg">function</em> is selected. Choose the <em
3750 class="arg">function</em> from:</p>
3759 <p>To print a complete list of <a href="command-line-options.html#function">-function</a> operators,
3760 use <a href="command-line-options.html#list">-list function</a>. Descriptions follow.</p>
3763 <dt><kbd>Polynomial</kbd></dt>
3766 <p>The <kbd>Polynomial</kbd> function takes an arbitrary number of parameters,
3767 these being the coefficients of a polynomial, in decreasing order of degree.
3768 That is, entering</p>
3770 <div style="text-align: center">
3771 -function Polynomial <em>a</em><sub><em>n</em></sub>,<em>a</em><sub><em>n</em>-1</sub>,...<em>a</em><sub>1</sub>,<em>a</em><sub>0</sub>
3774 <p>will invoke a polynomial function given by</p>
3776 <div style="text-align: center">
3777 <em>a</em><sub><em>n</em></sub> <b><em>u</em></b><sup><em>n</em></sup> +
3778 <em>a</em><sub><em>n</em>-1</sub> <b><em>u</em></b><sup><em>n</em>-1</sup> +
3779 ··· <em>a</em><sub>1</sub> <b><em>u</em></b> + <em>a</em><sub>0</sub>,
3782 <p>where <b><em>u</em></b> is pixel's original normalized channel value.</p>
3784 <p>The <kbd>Polynomial</kbd> function can be used in place of <kbd>Set</kbd>
3785 (the <em>constant</em> polynomial) and <kbd>Add</kbd>, <kbd>Divide</kbd>,
3786 <kbd>Multiply</kbd>, and <kbd>Subtract</kbd> (some <em>linear</em>
3787 polynomials) of the <a href="command-line-options.html#evaluate">-evaluate</a> operator. The <a
3788 href="command-line-options.html#level">-level</a> operator also affects channels linearly. Some
3789 correspondences follow.</p>
3796 <td>-evaluate Set <em class="arg">value</em> </td>
3797 <td>-function Polynomial <em class="arg">value</em></td>
3798 <td>(Constant functions; set <em class="arg">value</em>×100% gray when channels are RGB.)</td>
3801 <td>-evaluate Add <em class="arg">value</em> </td>
3802 <td>-function Polynomial 1,<em class="arg">value</em></td>
3805 <td>-evaluate Subtract <em class="arg">value</em> </td>
3806 <td>-function Polynomial 1,−<em class="arg">value</em></td>
3809 <td>-evaluate Multiply <em class="arg">value</em> </td>
3810 <td>-function Polynomial <em class="arg">value</em>,0</td>
3813 <td>+level black% x white%</td>
3814 <td>-function Polynomial A,B</td>
3815 <td>(Reduce contrast. Here, A=(white-black)/100 and B=black/100.)</td>
3819 <p>The <kbd>Polynomial</kbd> function gives great versatility, since
3820 polynomials can be used to fit any continuous curve to any degree of accuracy
3825 <dt><kbd>Sinusoid</kbd></dt>
3827 <p>The <kbd>Sinusoid</kbd> function can be used to vary the channel values
3828 sinusoidally by setting frequency, phase shift, amplitude, and a bias. These
3829 values are given as one to four parameters, as follows,</p>
3831 <div style="text-align: center">
3832 -function <kbd>Sinusoid</kbd> <em class="arg">freq</em>,[<em class="arg">phase</em>,[<em class="arg">amp</em>,[<em class="arg">bias</em>]]]
3835 <p>where <em>phase</em> is in degrees. (The domain [0,1] of the function
3836 corresponds to 0 through <em class="arg">freq</em>×360 degrees.)
3837 The result is that if a pixel's normalized channel value is originally
3838 <b><em>u</em></b>, its resulting normalized value is given by </p>
3840 <div style="text-align: center">
3841 <em class="arg">amp</em> * sin(2*π* (<em class="arg">freq</em> * <b><em>u</em></b> + <em class="arg">phase</em> / 360)) + <em class="arg">bias</em>
3844 <p> For example, the following generates a curve that starts and ends at 0.9
3845 (when <b><em>u</em></b>=0 and 1, resp.), oscillating three times between
3846 .7−.2=.5 and .7+.2=.9. </p>
3849 -function Sinusoid 3,-90,.2,.7
3852 <p>The default values of <em class="arg">amp</em> and <em
3853 class="arg">bias</em> are both .5. The default for <em class="arg">phase</em>
3856 <p>The <kbd>Sinusoid</kbd> function generalizes <kbd>Sin</kbd> and
3857 <kbd>Cos</kbd> of the <a href="command-line-options.html#evaluate">-evaluate</a> operator by allowing
3858 varying amplitude, phase and bias. The correspondence is as follows.</p>
3862 <td>-evaluate Sin <em class="arg">freq</em> </td>
3863 <td>-function Sinusoid <em class="arg">freq</em>,0 </td>
3866 <td>-evaluate Cos <em class="arg">freq</em> </td>
3867 <td>-function Sinusoid <em class="arg">freq</em>,90 </td>
3872 <dt><kbd>ArcSin</kbd></dt>
3874 <p>The <kbd>ArcSin</kbd> function generates the inverse curve of a Sinusoid,
3875 and can be used to generate cylindrical distortion and displacement maps.
3876 The curve can be adjusted relative to both the input values and output range
3879 <p style="text-align: center">
3880 -function <kbd>ArcSin</kbd> <em class="arg">width</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]]
3883 <p>with all values given in terms of normalized color values (0.0 for black,
3884 1.0 for white). Defaulting to values covering the full range from 0.0 to 1.0
3885 for bout input (<em class="arg">width</em>), and output (<em
3886 class="arg">width</em>) values. '<code>1.0,0.5,1.0,0.5</code>' </p>
3888 <p style="text-align: center">
3889 <em class="arg">range</em>/π * asin( 2/<em class="arg">width</em> * ( <b><em>u</em></b> - <em class="arg">center</em> ) ) + <em class="arg">bias</em>
3894 <dt><kbd>ArcTan</kbd></dt>
3896 <p>The <kbd>ArcTan</kbd> function generates a curve that smooth crosses from
3897 limit values at infinities, though a center using the given slope value.
3898 All these values can be adjusted via the arguments.</p>
3900 <p style="text-align: center">
3901 -function <kbd>ArcTan</kbd> <em class="arg">slope</em>,[<em class="arg">center</em>,[<em class="arg">range</em>,[<em class="arg">bias</em>]]]
3904 <p>Defaulting to '<code>1.0,0.5,1.0,0.5</code>'.
3907 <p style="text-align: center">
3908 <em class="arg">range</em>/π * atan( <em class="arg">slope</em>*π * ( <b><em>u</em></b> - <em class="arg">center</em> ) ) + <em class="arg">bias</em>
3916 <div style="margin: auto;">
3917 <h4><a id="fuzz"></a>-fuzz <em class="arg">distance</em>{<em class="arg">%</em>}</h4>
3920 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Colors within this <em class="arg">distance</em> are considered equal.</td><td style='text-align:right;'></td></tr></table>
3922 <p>A number of algorithms search for a target color. By default the color must
3923 be exact. Use this option to match colors that are close to the target color
3924 in RGB space. For example, if you want to automagically trim the edges of an
3925 image with <a href="command-line-options.html#trim">-trim</a> but the image was scanned and the target
3926 background color may differ by a small amount. This option can account for
3927 these differences.</p>
3929 <p>The <em class="arg">distance</em> can be in absolute intensity units or, by
3930 appending <kbd>%</kbd> as a percentage of the maximum possible intensity (255,
3931 65535, or 4294967295).</p>
3934 <div style="margin: auto;">
3935 <h4><a id="fx"></a>-fx <em class="arg">expression</em></h4>
3938 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a mathematical expression to an image or image channels.</td><td style='text-align:right;'></td></tr></table>
3940 <p>If the first character of <em class="arg">expression</em> is <kbd>@</kbd>,
3941 the expression is read from a file titled by the remaining characters in the
3944 <p>See <a href="fx.html">FX,
3945 The Special Effects Image Operator</a> for a detailed discussion of this
3949 <div style="margin: auto;">
3950 <h4><a id="gamma"></a>-gamma <em class="arg">value</em></h4>
3953 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>level of gamma correction.</td><td style='text-align:right;'></td></tr></table>
3955 <p>The same color image displayed on two different workstations may look
3956 different due to differences in the display monitor. Use gamma correction to
3957 adjust for this color difference. Reasonable values extend from
3958 <kbd>0.8</kbd> to <kbd>2.3</kbd>. Gamma less than 1.0 darkens the image and
3959 gamma greater than 1.0 lightens it. Large adjustments to image gamma may
3960 result in the loss of some image information if the pixel quantum size is only
3961 eight bits (quantum range 0 to 255).</p>
3963 <p>Gamma adjusts the image's channel values pixel-by-pixel according to
3964 a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the
3965 normalized or 0 to 1 color value. For example, using a value of gamma=2 is the
3966 same as taking the square root of the image.</p>
3968 <p>You can apply separate gamma values to the red, green, and blue channels of
3969 the image with a gamma value list delimited with commas (e.g.,
3970 <kbd>1.7,2.3,1.2</kbd>).</p>
3972 <p>Use <a href="command-line-options.html#gamma">+gamma <em class="arg">value</em></a> to set the
3973 image gamma level without actually adjusting the image pixels. This option
3974 is useful if the image is of a known gamma but not set as an image attribute
3975 (e.g. PNG images). Write the "file gamma" which is the reciprocal of the
3976 display gamma; e.g., if your image is sRGB and you want to write a PNG gAMA
3978 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert input.png +gamma .45455 output.png</span></p>(0.45455 is 1/2.2)</p>
3980 <p>Note that gamma adjustments are also available via the <a href="command-line-options.html#level">-level</a> operator.</p>
3982 <div style="margin: auto;">
3983 <h4><a id="gaussian-blur"></a>-gaussian-blur <em class="arg">radius</em><br />-gaussian-blur <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">bias</em></h4>
3986 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Blur the image with a Gaussian operator.</td><td style='text-align:right;'></td></tr></table>
3988 <p>Convolve the image with a Gaussian or normal distribution using the given
3989 <em class="arg" >Sigma</em> value. The formula is:</p>
3991 <div class="eqn"><img alt="gaussian distribution" width="243px" height="42px" src="../images/gaussian-blur.png"/>
3994 <p>The <em class="arg" >Sigma</em> value is the important argument, and
3995 determines the actual amount of blurring that will take place. </p>
3997 <p>The <em class="arg" >Radius</em> is only used to determine the size of the
3998 array which will hold the calculated Gaussian distribution. It should be an
3999 integer. If not given, or set to zero, IM will calculate the largest possible
4000 radius that will provide meaningful results for the Gaussian distribution.
4003 <p>The larger the <em class="arg" >Radius</em> the radius the slower the
4004 operation is. However too small a <em class="arg" >Radius</em>, and sever
4005 aliasing effects may result. As a guideline, <em class="arg" >Radius</em>
4006 should be at least twice the <em class="arg" >Sigma</em> value, though three
4007 times will produce a more accurate result. </p>
4009 <p>This differs from the faster <a href="command-line-options.html#blur">-blur</a> operator in that a
4010 full 2-dimensional convolution is used to generate the weighted average of the
4011 neighboring pixels. </p>
4013 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
4014 pixels which are outside the image proper are blurred into the final result.
4018 <div style="margin: auto;">
4019 <h4><a id="geometry"></a>-geometry <em class="arg">geometry</em></h4>
4022 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the preferred size and location of the image.</td><td style='text-align:right;'></td></tr></table>
4024 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4026 <div style="margin: auto;">
4027 <h4><a id="gravity"></a>-gravity <em class="arg">type</em></h4>
4030 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Sets the current gravity suggestion for various other settings and options.</td><td style='text-align:right;'></td></tr></table>
4032 <p>Choices include: <kbd>NorthWest</kbd>, <kbd>North</kbd>,
4033 <kbd>NorthEast</kbd>, <kbd>West</kbd>, <kbd>Center</kbd>, <kbd>East</kbd>,
4034 <kbd>SouthWest</kbd>, <kbd>South</kbd>, <kbd>SouthEast</kbd>. Use <a
4035 href="command-line-options.html#list">-list gravity</a> to get a complete list of <a
4036 href="command-line-options.html#gravity">-gravity</a> settings available in your ImageMagick
4039 <p>The direction you choose specifies where to position text or subimages. For
4040 example, a gravity of <kbd>Center</kbd> forces the text to be centered within
4041 the image. By default, the image gravity is <kbd>NorthWest</kbd>. See <a
4042 href="command-line-options.html#draw">-draw</a> for more details about graphic primitives. Only the
4043 text primitive of <a href="command-line-options.html#draw">-draw</a> is affected by the <a
4044 href="command-line-options.html#gravity">-gravity</a> option.</p>
4046 <p>The <a href="command-line-options.html#gravity">-gravity</a> option is also used in concert with the
4047 <a href="command-line-options.html#geometry">-geometry</a> setting and other settings or options that
4048 take <em class="arg">geometry</em> as an argument, such as the <a
4049 href="command-line-options.html#crop">-crop</a> option. </p>
4051 <p>If a <a href="command-line-options.html#gravity">-gravity</a> setting occurs before another option
4052 or setting having a <em class="arg">geometry</em> argument that specifies an
4053 offset, the offset is usually applied to the point within the image suggested
4054 by the <a href="command-line-options.html#gravity">-gravity</a> argument. Thus, in the following
4055 command, for example, suppose the file <kbd>image.png</kbd> has dimensions
4056 200x100. The offset specified by the argument to <a href="command-line-options.html#region">-region</a>
4057 is (−40,+20). The argument to <a href="command-line-options.html#gravity">-gravity</a> is
4058 <kbd>Center</kbd>, which suggests the midpoint of the image, at the point
4059 (100,50). The offset (−40,20) is applied to that point, giving
4060 (100−40,50+20)=(60,70), so the specified 10x10 region is located at
4061 that point. (In addition, the <a href="command-line-options.html#gravity">-gravity</a> affects the
4062 region itself, which is <em>centered</em> at the pixel
4063 coordinate (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>
4065 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -gravity Center -region 10x10-40+20 \ <br/> -negate output.png</span></p>
4066 <p>When used as an option to <a href="composite.html">composite</a>, <a
4067 href="command-line-options.html#gravity">-gravity</a> gives the direction that the image gravitates
4068 within the composite.</p>
4070 <p>When used as an option to <a href="montage.html">montage</a>, <a
4071 href="command-line-options.html#gravity">-gravity</a> gives the direction that an image gravitates
4072 within a tile. The default gravity is <kbd>Center</kbd> for this purpose.</p>
4075 <div style="margin: auto;">
4076 <h4><a id="green-primary"></a>-green-primary <em class="arg">x,y</em></h4>
4079 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>green chromaticity primary point.</td><td style='text-align:right;'></td></tr></table>
4082 <div style="margin: auto;">
4083 <h4><a id="hald-clut"></a>-hald-clut</h4>
4086 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a Hald color lookup table to the image.</td><td style='text-align:right;'></td></tr></table>
4088 <p>A Hald color lookup table is a 3-dimensional color cube mapped to 2
4089 dimensions. Create it with the <kbd>HALD:</kbd> prefix (e.g. HALD:8). You
4090 can apply any color transformation to the Hald image and then use this option
4091 to apply the transform to the image. </p>
4093 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png hald.png -hald-clut transform.png</span></p>
4094 <p>This option provides a convenient method for you to use Gimp or Photoshop
4095 to make color corrections to the Hald CLUT image and subsequently apply them
4096 to multiple images using an ImageMagick script. </p>
4098 <p>Note that the representation is only of the normal RGB color space and that
4099 the whole color value triplet is used for the interpolated lookup of the
4100 represented Hald color cube image. Because of this the operation is not <a
4101 href="command-line-options.html#channel" >-channel</a> setting effected, nor can it adjust or modify an
4102 images transparency or alpha/matte channel.</p>
4104 <p>See also <a href="command-line-options.html#clut" >-clut</a> which provides color value replacement
4105 of the individual color channels, usually involving a simpler gray-scale
4106 image. E.g: gray-scale to color replacement, or modification by a histogram
4110 <div style="margin: auto;">
4111 <h4><a id="help"></a>-help</h4>
4114 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print usage instructions.</td><td style='text-align:right;'></td></tr></table>
4116 <div style="margin: auto;">
4117 <h4><a id="highlight-color"></a>-highlight-color <em class="arg">color</em></h4>
4120 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>when comparing images, emphasize pixel differences with this color.</td><td style='text-align:right;'></td></tr></table>
4122 <div style="margin: auto;">
4123 <h4><a id="iconGeometry"></a>-iconGeometry <em class="arg">geometry</em></h4>
4126 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the icon geometry.</td><td style='text-align:right;'></td></tr></table>
4128 <p>Offsets, if present in the geometry specification, are handled in the same
4129 manner as the <a href="command-line-options.html#geometry">-geometry</a> option, using X11 style to
4130 handle negative offsets.</p>
4132 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4134 <div style="margin: auto;">
4135 <h4><a id="iconic"></a>-iconic</h4>
4138 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>iconic animation.</td><td style='text-align:right;'></td></tr></table>
4140 <div style="margin: auto;">
4141 <h4><a id="identify"></a>-identify</h4>
4144 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>identify the format and characteristics of the image.</td><td style='text-align:right;'></td></tr></table>
4146 <p>This information is printed: image scene number; image name; image size;
4147 the image class (<em class="arg">DirectClass</em> or <em
4148 class="arg">PseudoClass</em>); the total number of unique colors; and the
4149 number of seconds to read and transform the image. Refer to <a href="miff.html">MIFF</a> for
4150 a description of the image class.</p>
4152 <p>If <a href="command-line-options.html#colors">-colors</a> is also specified, the total unique colors
4153 in the image and color reduction error values are printed. Refer to <a
4154 href="quantize.html">color
4155 reduction algorithm</a> for a description of these values.</p>
4157 <p>If <a href="command-line-options.html#verbose">-verbose</a> precedes this option, copious
4158 amounts of image properties are displayed including image statistics, profiles,
4159 image histogram, and others.</p>
4161 <div style="margin: auto;">
4162 <h4><a id="ift"></a>-ift</h4>
4165 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implements the inverse discrete Fourier transform (DFT).</td><td style='text-align:right;'></td></tr></table>
4167 <p>This option is new as of ImageMagick 6.5.4-3 (and now working for Windows
4168 users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase
4169 images from the frequency domain to a single image in the normal or spatial
4170 domain. See for example, <a
4171 href="http://en.wikipedia.org/wiki/Fourier_transform">Fourier Transform</a>,
4172 <a href="http://en.wikipedia.org/wiki/DFT">Discrete Fourier Transform</a> and
4173 <a href="http://en.wikipedia.org/wiki/FFT">Fast Fourier Transform</a>.</p>
4175 <p>For example, depending upon the image format used to store the result of
4176 the <a href="command-line-options.html#fft">-fft</a>, one would use either</p>
4178 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert fft_image.miff -ift fft_image_ift.png</span></p>
4181 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png</span></p>
4183 <p>The resulting image may need to be cropped due to padding introduced when
4184 the original image, prior to the <a href="command-line-options.html#fft">-fft</a> or <a
4185 href="command-line-options.html#fft">+fft</a>, was not square or even dimensioned. Any padding is at
4186 the right and/or bottom sides of the image.</p>
4188 <p>The <a href="http://www.fftw.org/">FFTW</a> delegate library is required to
4189 use <a href="command-line-options.html#ift">-ift</a>.</p>
4191 <p>Use <a href="command-line-options.html#ift">+ift</a> (with HDRI enabled) to transform a pair of real
4192 and imaginary images from the frequency domain to a single image in the normal
4193 (spatial) domain.</p>
4195 <div style="margin: auto;">
4196 <h4><a id="immutable"></a>-immutable</h4>
4199 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make image immutable.</td><td style='text-align:right;'></td></tr></table>
4201 <div style="margin: auto;">
4202 <h4><a id="implode"></a>-implode <em class="arg">factor</em></h4>
4205 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>implode image pixels about the center.</td><td style='text-align:right;'></td></tr></table>
4207 <div style="margin: auto;">
4208 <h4><a id="insert"></a>-insert <em class="arg">index</em></h4>
4211 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>insert the last image into the image sequence.</td><td style='text-align:right;'></td></tr></table>
4213 <p>This option takes last image in the current image sequence and inserts it
4214 at the given index. If a negative index is used, the insert position is
4215 calculated before the last image is removed from the sequence. As such
4216 <kbd>-insert -1</kbd> will result in no change to the image sequence.</p>
4218 <p>The <kbd>+insert</kbd> option is equivalent to <kbd>-insert -1</kbd>. In
4219 other words, insert the last image, at the end of the current image sequence.
4220 Consequently this has no effect on the image sequence order.</p>
4222 <div style="margin: auto;">
4223 <h4><a id="intent"></a>-intent <em class="arg">type</em></h4>
4226 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>use this type of rendering intent when managing the image color.</td><td style='text-align:right;'></td></tr></table>
4228 <p>Use this option to affect the color management operation of an image (see
4229 <a href="command-line-options.html#profile">-profile</a>). Choose from these intents: <kbd>Absolute,
4230 Perceptual, Relative, Saturation</kbd>.</p>
4232 <p>The default intent is Perceptual for the sRGB colorspace and undefined for the RGB and gray colorspaces.</p>
4234 <p>To print a complete list of rendering intents, use <a href="command-line-options.html#list">-list intent</a>.</p>
4236 <div style="margin: auto;">
4237 <h4><a id="interlace"></a>-interlace <em class="arg">type</em></h4>
4240 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the type of interlacing scheme.</td><td style='text-align:right;'></td></tr></table>
4254 <p>This option is used to specify the type of interlacing scheme for raw image
4255 formats such as <kbd>RGB</kbd> or <kbd>YUV</kbd>.</p>
4257 <p><kbd>None</kbd> means do not interlace (RGBRGBRGBRGBRGBRGB...),</p>
4259 <p><kbd>Line</kbd> uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.</p>
4261 <p><kbd>Plane</kbd> uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).</p>
4263 <p><kbd>Partition</kbd> is like plane except the different planes are saved to
4264 individual files (e.g. image.R, image.G, and image.B).</p>
4266 <p>Use <kbd>Line</kbd> or <kbd>Plane</kbd> to create an <kbd>interlaced
4267 PNG</kbd> or <kbd>GIF</kbd> or <kbd>progressive JPEG</kbd> image.</p>
4269 <p>To print a complete list of interlacing schemes, use <a href="command-line-options.html#list">-list
4272 <div style="margin: auto;">
4273 <h4><a id="interpolate"></a>-interpolate <em class="arg">type</em></h4>
4276 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the pixel color interpolation method to use when looking up a color based on a floating point or real value.</td><td style='text-align:right;'></td></tr></table>
4278 <p>When looking up the color of a pixel using a non-integer floating point
4279 value, you typically fall in between the pixel colors defined by the source
4280 image. This setting determines how the color is determined from the colors of
4281 the pixels surrounding that point. That is how to determine the color of a
4282 point that falls between two, or even four different colored pixels. </p>
4285 integer The color of the top-left pixel (floor function)
4286 nearest-neighbor The nearest pixel to the lookup point (rounded function)
4287 average The average color of the surrounding four pixels
4288 bilinear A double linear interpolation of pixels (the default)
4289 mesh Divide area into two flat triangular interpolations
4290 bicubic Fitted bicubic-spines of surrounding 16 pixels
4291 spline Direct spline curves (colors are blurred)
4292 filter Use resize <a href="command-line-options.html#filter">-filter</a> settings
4295 <p>This most important for distortion operators such as <a href="command-line-options.html#distort"
4296 >-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, <a href="command-line-options.html#transform"
4297 >-transform</a> and <a href="command-line-options.html#fx" >-fx</a>. </p>
4299 <p>To print a complete list of interpolation methods, use <a href="command-line-options.html#list">-list interpolate</a>.</p>
4301 <p>See also <a href="command-line-options.html#virtual-pixel" >-virtual-pixel</a>, for control of the
4302 lookup for positions outside the boundaries of the image. </p>
4305 <div style="margin: auto;">
4306 <h4><a id="interline-spacing"></a>-interline-spacing <em class="arg">value</em></h4>
4309 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two text lines.</td><td style='text-align:right;'></td></tr></table>
4311 <div style="margin: auto;">
4312 <h4><a id="interword-spacing"></a>-interword-spacing <em class="arg">value</em></h4>
4315 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two words.</td><td style='text-align:right;'></td></tr></table>
4317 <div style="margin: auto;">
4318 <h4><a id="kerning"></a>-kerning <em class="arg">value</em></h4>
4321 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the space between two letters.</td><td style='text-align:right;'></td></tr></table>
4323 <div style="margin: auto;">
4324 <h4><a id="label"></a>-label <em class="arg">name</em></h4>
4327 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>assign a label to an image.</td><td style='text-align:right;'></td></tr></table>
4329 <p>Use this option to assign a specific label to the image, as it is read in
4330 or created. You can use the <a href="command-line-options.html#set" >-set</a> operation to re-assign
4331 a the labels of images already read in. Image formats such as TIFF, PNG,
4332 MIFF, supports saving the label information with the image.</p>
4334 <p>When saving an image to a <em class="arg">PostScript</em> file, any label
4335 assigned to an image is used as a header string to print above the postscript
4338 <p>You can include the image filename, type, width, height, or other image
4339 attribute by embedding special format character. See <a href="escape.html">Format and Print Image
4340 Properties</a> for details of the percent escape codes.</p>
4345 -label "%m:%f %wx%h" bird.miff
4348 <p>assigns an image label of <kbd>MIFF:bird.miff 512x480</kbd> to the
4349 "<kbd>bird.miff</kbd>" image and whose width is 512 and height is 480, as it
4350 is read in. If a <a href="command-line-options.html#label">+label</a> option was used instead, any
4351 existing label present in the image would be used. You can remove all labels
4352 from an image by assigning the empty string. </p>
4354 <p>A label is not drawn on the image, but is embedded in the image datastream
4355 via <em>Label</em> tag or similar mechanism. If you want the label to be
4356 visible on the image itself, use the <a href="command-line-options.html#draw">-draw</a> option, or
4357 during the final processing in the creation of a image montage.</p>
4359 <p>If the first character of <em class="arg">string</em> is <em
4360 class="arg">@</em>, the image label is read from a file titled by the
4361 remaining characters in the string. Labels in a file are literal, no embedded
4362 formatting characters are recognized.</p>
4365 <div style="margin: auto;">
4366 <h4><a id="lat"></a>-lat <em class="arg">width</em><br />-lat <em class="arg">width</em>x<em class="arg">height</em>{<em class="arg">+-</em>}<em class="arg">offset</em>{<em class="arg">%</em>}</h4>
4369 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform local adaptive threshold.</td><td style='text-align:right;'></td></tr></table>
4371 <p>Adaptively threshold each pixel based on the value of pixels in a
4372 surrounding window. If the current pixel is lighter than this average plus
4373 the optional <kbd>offset</kbd>, then it is made white, otherwise it is made
4374 black. Small variations in pixel values such as found in scanned documents
4375 can be ignored if offset is positive. A negative offset will make it more
4376 sensitive to those small variations. </p>
4378 <p>This is commonly used to threshold images with an uneven background. It is
4379 based on the assumption that average color of the small window is the
4380 the local background color, from which to separate the foreground color. </p>
4383 <div style="margin: auto;">
4384 <h4><a id="layers"></a>-layers <em class="arg">method</em></h4>
4387 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>handle multiple images forming a set of image layers or animation frames.</td><td style='text-align:right;'></td></tr></table>
4389 <p>Perform various image operation methods to a ordered sequence of images
4390 which may represent either a set of overlaid 'image layers', a GIF disposal
4391 animation, or a fully-'coalesced' animation sequence. </p>
4396 <th align="left" style="width: 8%">Method</th>
4397 <th align="left">Description</th>
4401 <td valign="top">compare-any</td>
4402 <td valign="top">Crop the second and later frames to the smallest rectangle
4403 that contains all the differences between the two images. No GIF <a
4404 href="command-line-options.html#dispose" >-dispose</a> methods are taken into account. </td>
4407 <tr><td></td><td>This exactly the same as the <a href="command-line-options.html#deconstruct"
4408 >-deconstruct</a> operator, and does not preserve animations normal
4409 working, especially when animation used layer disposal methods such as
4410 '<kbd>Previous</kbd>' or '<kbd>Background</kbd>'. </td>
4414 <td valign="top">compare-clear</td>
4415 <td valign="top">As '<kbd>compare-any</kbd>' but crop to the bounds of any
4416 opaque pixels which become transparent in the second frame. That is the
4417 smallest image needed to mask or erase pixels for the next frame. </td>
4421 <td valign="top">compare-overlay</td>
4422 <td valign="top">As '<kbd>compare-any</kbd>' but crop to pixels that add
4423 extra color to the next image, as a result of overlaying color pixels.
4424 That is the smallest single overlaid image to add or change colors. </td>
4427 <tr><td></td><td>This can be used with the <a href="command-line-options.html#compose" >-compose</a> alpha
4428 composition method '<kbd>change-mask</kbd>', to reduce the image to
4429 just the pixels that need to be overlaid. </td>
4433 <td valign="top">coalesce</td>
4434 <td valign="top">Equivalent to a call to the <a href="command-line-options.html#coalesce"
4435 >-coalesce</a> operator. Apply the layer disposal methods set in the
4436 current image sequence to form a fully defined animation sequence, as
4437 it should be displayed. Effectively converting a GIF animation into a
4438 'film strip'-like animation. </td>
4442 <td valign="top">composite</td>
4443 <td valign="top">Alpha Composition of two image lists, separated by a
4444 "<kbd>null:</kbd>" image, with the destination image list first, and
4445 the source images last. An image from each list are composited
4446 together until one list is finished. The separator image and source
4447 image lists are removed. </td>
4452 <td>The <a href="command-line-options.html#geometry" >-geometry</a> offset is adjusted according
4453 to <a href="command-line-options.html#gravity" >-gravity</a> in accordance of the virtual
4454 canvas size of the first image in each list. Unlike a normal <a
4455 href="command-line-options.html#composite" >-composite</a> operation, the canvas offset is also
4456 added to the final composite positioning of each image. </td> </tr>
4459 <td>If one of the image lists only contains one image, that image is
4460 applied to all the images in the other image list, regardless of which
4461 list it is. In this case it is the image meta-data of the list which
4467 <td valign="top">dispose</td>
4468 <td valign="top">This like '<kbd>coalesce</kbd>' but shows the look of
4469 the animation after the layer disposal method has been applied, before
4470 the next sub-frame image is overlaid. That is the 'dispose' image that
4471 results from the application of the GIF <a href="command-line-options.html#dispose"
4472 >-dispose</a> method. This allows you to check what
4473 is going wrong with a particular animation you may be developing.
4478 <td valign="top">flatten</td>
4479 <td valign="top">Create a canvas the size of the first images virtual
4480 canvas using the current <a href="command-line-options.html#background" >-background</a> color,
4481 and <a href="command-line-options.html#compose" >-compose</a> each image in turn onto that
4482 canvas. Images falling outside that canvas is clipped. Final
4483 image will have a zero virtual canvas offset. </td>
4487 <td>This usually used as one of the final 'image layering' operations
4488 overlaying all the prepared image layers into a final image. </td>
4492 <td>For a single image this method can also be used to fillout a virtual
4493 canvas with real pixels, or to underlay an opaque color to remove
4494 transparency from an image.</td>
4499 <td valign="top">merge</td>
4500 <td valign="top">As 'flatten' method but merging all the given image
4501 layers to create a new layer image just large enough to hold all the
4502 image without clipping or extra space. The new images virtual offset
4503 will preserve the position of the new layer, even if this offset is
4504 negative. The virtual canvas size of the first image is preserved.
4508 <tr><td></td><td>Caution is advised when handling image layers with
4509 negative offsets as few image file formats handle them correctly.
4510 Following this operation method with <a href="command-line-options.html#repage" >+repage</a>
4511 will remove the layer offset, and create a image in which all the
4512 overlaid image positions relative to each other is preserved, though
4513 not necessarily exactly where you specified them.
4517 <tr><td></td><td>See also 'trim-bounds' below which is closely related but
4518 without doing the'flatten' to merge the images together. </td>
4522 <td valign="top">mosaic</td>
4523 <td valign="top">As 'flatten' method but expanding the initial canvas size
4524 of the first image in a positive direction only so as to hold all the
4525 image layers. However as a virtual canvas is 'locked' to the origin,
4526 by its own definition, image layers with a negative offsets will still
4527 become clipped by the top and left edges. See 'merge' or 'trim-bounds'
4528 if this could be a problem. </td>
4532 <tr><td></td><td>This method is commonly used to layout individual image
4533 using various offset but without knowing the final canvas size. The
4534 resulting image will, like 'flatten' not have any virtual offset, so
4535 can be saved to any image file format. </td>
4540 <td valign="top">optimize</td>
4541 <td valign="top">Optimize a coalesced animation, into GIF animation using
4542 a number of general techniques. This currently a short cut to
4543 apply both the '<kbd>optimize-frame</kbd>', and
4544 '<kbd>optimize-transparency</kbd>' methods but may be expanded to
4545 include other optimization methods as they are developed. </td>
4549 <td valign="top">optimize-frame</td>
4550 <td valign="top">Optimize a coalesced animation, into GIF animation by
4551 reducing the number of pixels per frame as much as possible by
4552 attempting to pick the best layer disposal method to use, while ensuring
4553 the result will continue to animate properly. </td>
4556 <tr><td></td><td> There is no guarantee that the best optimization is found.
4557 But then no reasonably fast GIF optimization algorithm can do this.
4558 However this does seem to do better than most other GIF frame
4559 optimizers seen. </td>
4563 <td valign="top">optimize-plus</td>
4564 <td valign="top">As '<kbd>optimize-frame</kbd>' but attempt to improve the
4565 overall optimization by adding extra frames to the animation, without
4566 changing the final look or timing of the animation. The frames are
4567 added to attempt to separate the clearing of pixels from the
4568 overlaying of new additional pixels from one animation frame to the
4569 next. If this does not improve the optimization (for the next frame
4570 only), it will fall back to the results of the previous normal
4571 '<kbd>optimize-frame</kbd>' technique. </td>
4574 <tr><td></td><td>There is the possibility that the change in the disposal
4575 style will result in a worsening in the optimization of later frames,
4576 though this is unlikely. In other words there no guarantee that it is
4577 better than the normal '<kbd>optimize-frame</kbd>' technique. For some
4578 animations however you can get a vast improvement in the final
4579 animation size. </td>
4583 <td valign="top">optimize-transparency</td>
4584 <td valign="top">Given a GIF animation, replace any pixel in the sub-frame
4585 overlay images with transparency, if it does not change the resulting
4586 animation by more than the current <a href="command-line-options.html#fuzz" >-fuzz</a> factor.
4590 <tr><td></td><td>This should allow a existing frame optimized GIF animation
4591 to compress into a smaller file size due to larger areas of one
4592 (transparent) color rather than a pattern of multiple colors repeating
4593 the current disposed image of the last frame. </td>
4597 <td valign="top">remove-dups</td>
4598 <td valign="top">Remove (and merge time delays) of duplicate consecutive
4599 images, so as to simplify layer overlays of coalesced animations.
4603 <tr><td></td><td>Usually this a result of using a constant time delay
4604 across the whole animation, or after a larger animation was split into
4605 smaller sub-animations. The duplicate frames could also have been
4606 used as part of some frame optimization methods. </td>
4610 <td valign="top">remove-zero</td>
4611 <td valign="top">Remove any image with a zero time delay, unless ALL the
4612 images have a zero time delay (and is not a proper timed animation, a
4613 warning is then issued). </td>
4616 <tr><td></td><td>In a GIF animation, such images are usually frames which
4617 provide partial intermediary updates between the frames that are
4618 actually displayed to users. These frames are usually added for
4619 improved frame optimization in GIF animations. </td>
4623 <td valign="top">trim-bounds</td>
4624 <td valign="top">Find the bounds of all the images in the current
4625 image sequence, then adjust the offsets so all images are contained on
4626 a minimal positive canvas. None of the image data is modified or
4627 merged, only the individual image virtual canvas size and offset.
4628 All the images is given the same canvas size, and and will have
4629 a positive offset, but will remain in the same position relative to
4630 each other. As a result of the minimal canvas size at least one image
4631 will touch every edge of that canvas. The image data touching those
4632 edges however may be transparent. </td>
4635 <tr><td></td><td>The result is much like if you used 'merge' followed by a
4636 <a href="command-line-options.html#repage" >+repage</a> option, except that all the images
4637 have been kept separate. If 'flatten' is used after using
4638 'trim-bounds' you will get the same result. </td>
4644 <p>To print a complete list of layer types, use <a href="command-line-options.html#list">-list layers</a>.</p>
4646 <p>The operators <a href="command-line-options.html#coalesce" >-coalesce</a>, <a href="command-line-options.html#deconstruct"
4647 >-deconstruct</a>, <a href="command-line-options.html#flatten" >-flatten</a>, and <a href="command-line-options.html#mosaic"
4648 >-mosaic</a> are only aliases for the above methods and may be depreciated in
4649 the future. Also see <a href="command-line-options.html#page" >-page</a>, <a href="command-line-options.html#repage"
4650 >-repage</a> operators, the <a href="command-line-options.html#compose" >-compose</a> setting, and the
4651 GIF <a href="command-line-options.html#dispose" >-dispose</a> and <a href="command-line-options.html#delay" >-delay</a>
4655 <div style="margin: auto;">
4656 <h4><a id="level"></a>-level <em class="arg">black_point</em>{,<em class="arg">white_point</em>}{<em class="arg">%</em>}{,<em class="arg">gamma</em>}</h4>
4659 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>adjust the level of image channels.</td><td style='text-align:right;'></td></tr></table>
4661 <p>Given one, two or three values delimited with commas: black-point,
4662 white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black and
4663 white points range from 0 to <em class="QR">QuantumRange</em>, or from 0 to
4664 100%; if the white point is omitted it is set to (<em
4665 class="QR">QuantumRange</em> - black_point), so as to center contrast changes.
4666 If a <kbd>%</kbd> sign is present anywhere in the string, both black and white
4667 points are percentages of the full color range. Gamma will do a <a
4668 href="command-line-options.html#gamma">-gamma</a> adjustment of the values. If it is omitted, the
4669 default of 1.0 (no gamma correction) is assumed.</p>
4671 <p>In normal usage (<kbd>-level</kbd>) the image values are stretched so that
4672 the given '<kbd>black_point</kbd>' value in the original image is set to zero
4673 (or black), while the given '<kbd>white_point</kbd>' value is set to <em
4674 class="QR">QuantumRange</em> (or white). This provides you with direct
4675 contrast adjustments to the image. The '<kbd>gamma</kbd>' of the resulting
4676 image will then be adjusted. </p>
4678 <p>From ImageMagick v6.4.1-9 using the plus form of the operator
4679 (<kbd>+level</kbd>) or adding the special '!' flag anywhere in the argument
4680 list, will cause the operator to do the reverse of the level adjustment. That
4681 is a zero, or <em class="QR">QuantumRange</em> value (black, and white, resp.)
4682 in the original image, is adjusted to the given level values, allowing you to
4683 de-contrast, or compress the channel values within the image. The
4684 '<kbd>gamma</kbd>' is adjusted before the level adjustment to de-contrast the
4687 <p>Only the channels defined by the current <a href="command-line-options.html#channel">-channel</a>
4688 setting are adjusted (defaults to RGB color channels only), allowing you to
4689 limit the effect of this operator. </p>
4691 <p>Please note that the transparency channel is treated as 'matte'
4692 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
4695 <div style="margin: auto;">
4696 <h4><a id="level-colors"></a>-level-colors {<em
4697 class="arg">black_color</em>}{,}{<em class="arg">white_color</em>}</h4>
4700 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>adjust the level of an image using the provided dash separated colors.</td><td style='text-align:right;'></td></tr></table>
4702 <p>This function is exactly like <a href="command-line-options.html#level">-level</a>, except that the
4703 value value for each color channel is determined by the
4704 '<kbd>black_color</kbd>' and '<kbd>white_color</kbd>' colors given (as
4705 described under the <a href="command-line-options.html#fill">-fill</a> option). </p>
4707 <p>This effectually means the colors provided to <kbd>-level-colors</kbd>
4708 is mapped to become 'black' and 'white' respectively, with all the other
4709 colors linearly adjusted (or clipped) to match that change. Each channel is
4710 adjusted separately using the channel values of the colors specified. </p>
4712 <p>On the other hand the plus form of the operator (<kbd>+level-colors</kbd>)
4713 will map the image color 'black' and 'white' to the given colors
4714 respectively, resulting in a gradient (de-contrasting) tint of the image to
4715 those colors. This can also be used to convert a plain gray-scale image into a
4716 one using the gradient of colors specified. </p>
4718 <p>By supplying a single color with a comma separator either before or after
4719 that color, will just replace the respective 'black' or 'white' point
4720 respectively. But if no comma separator is provided, the given color is
4721 used for both the black and white color points, making the operator either
4722 threshold the images around that color (- form) or set all colors to that
4723 color (+ form). </p>
4726 <div style="margin: auto;">
4727 <h4><a id="limit"></a>-limit <em class="arg">type value</em></h4>
4730 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the pixel cache resource limit.</td><td style='text-align:right;'></td></tr></table>
4732 <p>Choose from: <kbd>area</kbd>, <kbd>disk</kbd>, <kbd>file</kbd>,
4733 <kbd>map</kbd>, <kbd>memory</kbd>, <kbd>threads</kbd>, or <kbd>time</kbd>.</p>
4735 <p>The value for <kbd>file</kbd> is in number of files. The other limits are
4736 in bytes. Define arguments for the memory, map, area, and disk resource limits
4737 with SI prefixes (.e.g 100MB).<p>
4739 <p>By default the limits are 768 files, 2GB of image area, 1.5GiB memory, 8GiB
4740 memory map, and 18.45EB of disk. These limits are adjusted relative to the
4741 available resources on your computer if this information is available. When
4742 any limit is reached, ImageMagick fails in some fashion but attempts to take
4743 compensating actions, if possible. For example, the following limits
4747 -limit memory 32MiB -limit map 64MiB
4750 <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>
4752 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>identify -list resource</span><span class='crtout'></span></p><pre class="text">
4753 File Area Memory Map Disk Thread Time
4754 ------------------------------------------------------------------------------
4755 768 12.404GB 8.6642GiB 23.104GiB 18.446744EB 8 unlimited
4758 <p>Requests for pixel storage to keep intermediate images are satisfied by one
4759 of three resource categories: in-memory pool, memory-mapped files pool, and
4760 disk pool (in that order) depending on the <a href="command-line-options.html#limit">‑limit</a> settings
4761 and whether the system honors a resource request. If the total size of
4762 allocated pixel storage in the given pool reaches the corresponding limit, the
4763 request is passed to the next pool. Additionally, requests that exceed the
4764 <kbd>area</kbd> limit automagically are allocated on disk.</p>
4766 <p>To illustrate how ImageMagick utilizes resource limits, consider a typical
4767 image resource request. First, ImageMagick tries to allocate the pixels in
4768 memory. The request might be denied if the resource request exceeds the
4769 <kbd>memory</kbd> limit or if the system does not honor the request. If
4770 a memory request is not honored, the pixels are allocated to disk and the file
4771 is memory-mapped. However, if the allocation request exceeds the
4772 <kbd>map</kbd> limit, the resource allocation goes to disk. In all cases, if
4773 the resource request exceeds the <kbd>area</kbd> limit, the pixels are
4774 automagically cached to disk. If the disk has a hard limit, the program
4777 <p>In most cases you simply do not need to concern yourself with resource
4778 limits. ImageMagick chooses reasonable defaults and most images do not tax
4779 your computer resources. Where limits do come in handy is when you process
4780 images that are large or on shared systems where ImageMagick can consume all
4781 or most of the available memory. In this case, the ImageMagick workflow slows
4782 other processes or, in extreme cases, brings the system to a halt. Under
4783 these circumstances, setting limits give some assurances that the ImageMagick
4784 workflow will not interfere with other concurrent uses of the computer. For
4785 example, assume you have a web interface that processes images uploaded from
4786 the Internet. To assure ImageMagick does not exceed 10mb of memory you can
4787 simply set the area limit to 10mb:</p>
4793 <p>Now whenever a large image is processed, the pixels are automagically
4794 cached to disk instead of memory. This of course implies that large images
4795 typically process very slowly, simply because pixel processing in memory can
4796 be an order of magnitude faster than on disk. Because your web site users
4797 might inadvertently upload a huge image to process, you should set a disk
4801 -limit area 10mb -limit disk 500mb
4804 <p>Here ImageMagick stops processing if an image requires more than 500MB of disk storage.</p>
4806 <p>In addition to command-line resource limit option, resources can be set
4807 with <a href="resources.html#environment" >environment variables</a>. Set the
4808 environment variables <kbd>MAGICK_AREA_LIMIT</kbd>,
4809 <kbd>MAGICK_DISK_LIMIT</kbd>, <kbd>MAGICK_FILE_LIMIT</kbd>,
4810 <kbd>MAGICK_MEMORY_LIMIT</kbd>, <kbd>MAGICK_MAP_LIMIT</kbd>,
4811 <kbd>MAGICK_THREAD_LIMIT</kbd>, <kbd>MAGICK_TIME_LIMIT</kbd> for limits of
4812 image area, disk space, open files, heap memory, memory map, number of threads
4813 of execution, and maximum elapsed time in seconds respectively.</p>
4815 <p> Inquisitive users can try adding <a href="command-line-options.html#debug">-debug cache</a> to
4816 their commands and then scouring the generated output for references to the
4817 pixel cache, in order to determine how the pixel cache was allocated and how
4818 resources were consumed. Advanced Unix/Linux users can pipe that output
4819 through <kbd>grep memory|open|destroy|disk</kbd> for more readable sifting.
4822 <p>For more about ImageMagick's use of resources, see the section <b>Cache
4823 Storage and Resource Requirements</b> on the <a href="architecture.html#cache
4824 ">Architecture</a> page. </p>
4826 <div style="margin: auto;">
4827 <h4><a id="linear-stretch"></a>-linear-stretch <em class="arg">black-point</em><br />-linear-stretch <em class="arg">black-point</em>{x<em class="arg">white-point</em>}{<em class="arg">%</em>}}</h4>
4830 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Linear with saturation stretch.</td><td style='text-align:right;'></td></tr></table>
4832 <p>This is very similar to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a>,
4833 and uses a 'histogram bin' to determine the range of color values that needs to
4834 be stretched. However it then stretches those colors using the <a
4835 href="command-line-options.html#level" >-level</a> operator.</p>
4837 <p>As such while the initial determination may have 'binning' round off
4838 effects, the image colors are stretched mathematically, rather than using the
4839 histogram bins. This makes the operator more accurate. </p>
4841 <p>note however that a <a href="command-line-options.html#linear-stretch" >-linear-stretch</a> of
4842 '<kbd>0</kbd>' does nothing, while a value of '<kbd>1</kbd>' does a near
4843 perfect stretch of the color range. </p>
4845 <p>See also <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect'
4846 normalization of mathematical images. </p>
4848 <p>This operator is under review for re-development. </p>
4851 <div style="margin: auto;">
4852 <h4><a id="linewidth"></a>-linewidth</h4>
4855 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the line width for subsequent draw operations.</td><td style='text-align:right;'></td></tr></table>
4857 <div style="margin: auto;">
4858 <h4><a id="liquid-rescale"></a>-liquid-rescale <em class="arg">geometry</em></h4>
4861 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>rescale image with seam-carving.</td><td style='text-align:right;'></td></tr></table>
4863 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
4865 <div style="margin: auto;">
4866 <h4><a id="list"></a>-list <em class="arg">type</em></h4>
4869 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Print a list of supported arguments for various options or settings. Choose from these list types:</td><td style='text-align:right;'></td></tr></table>
4872 Align Alpha Boolean Channel
4873 Class ClipPath Coder Color
4874 Colorspace Command Compose Compress
4875 Configure DataType Debug Decoration
4876 Delegate Direction Dispose Distort
4877 Dither Endian Evaluate FillRule
4878 Filter Font Format Function
4879 Gravity ImageList Intent Interlace
4880 Interpolate Kernel Layers LineCap
4881 LineJoin List Locale LogEvent
4882 Log Magic Method Metric
4883 Mime Mode Morphology Module
4884 Noise Orientation Policy PolicyDomain
4885 PolicyRights Preview Primitive QuantumFormat
4886 Resource SparseColor Storage Stretch
4887 Style Threshold Type Units
4888 Validate VirtualPixel
4891 <p>These lists vary depending on your version of ImageMagick. Use "<kbd>-list
4892 list</kbd>" to get a complete listing of all the "<kbd>-list</kbd>" arguments
4895 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>identify -list list</span></p>
4896 <div style="margin: auto;">
4897 <h4><a id="log"></a>-log <em class="arg">string</em></h4>
4900 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify format for debug log.</td><td style='text-align:right;'></td></tr></table>
4902 <p>This option specifies the format for the log printed when the <a
4903 href="command-line-options.html#debug">-debug</a> option is active.</p>
4905 <p>You can display the following components by embedding special format
4925 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -debug coders -log "%u %m:%l %e" in.gif out.png</span></p>
4926 <p>The default behavior is to print all of the components.</p>
4928 <div style="margin: auto;">
4929 <h4><a id="loop"></a>-loop <em class="arg">iterations</em></h4>
4932 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>add Netscape loop extension to your GIF animation.</td><td style='text-align:right;'></td></tr></table>
4934 <p>Set iterations to zero to repeat the animation an infinite number of times,
4935 otherwise the animation repeats itself up to <em class="arg">iterations</em>
4938 <div style="margin: auto;">
4939 <h4><a id="lowlight-color"></a>-lowlight-color <em class="arg">color</em></h4>
4942 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>when comparing images, de-emphasize pixel differences with this color.</td><td style='text-align:right;'></td></tr></table>
4944 <div style="margin: auto;">
4945 <h4><a id="magnify"></a>-magnify <em class="arg">factor</em></h4>
4948 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>magnify the image.</td><td style='text-align:right;'></td></tr></table>
4951 <div style="margin: auto;">
4952 <h4><a id="map"></a>-map <em class="arg">type</em></h4>
4955 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Display image using this <em class="arg">type</em>.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
4957 <p>Choose from these <em class="arg">Standard Colormap</em> types:</p>
4968 <p>The <em class="arg">X server</em> must support the <em class="arg">Standard
4969 Colormap</em> you choose, otherwise an error occurs. Use <kbd>list</kbd> as
4970 the type and <kbd>display</kbd> searches the list of colormap types in
4971 <kbd>top-to-bottom</kbd> order until one is located. See <em
4972 class="arg">xstdcmap(1)</em> for one way of creating Standard Colormaps.</p>
4975 <div style="margin: auto;">
4976 <h4><a id="map_stream_"></a>-map <em class="arg">components</em></h4>
4979 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pixel map.</td><td style='text-align:right;'>[<a href="stream.html">stream</a>]</td></tr></table>
4981 <p>Here are the valid components of a map:</p>
4984 r red pixel component
4985 g green pixel component
4986 b blue pixel component
4987 a alpha pixel component (0 is transparent)
4988 o opacity pixel component (0 is opaque)
4989 i grayscale intensity pixel component
4990 c cyan pixel component
4991 m magenta pixel component
4992 y yellow pixel component
4993 k black pixel component
4994 p pad component (always 0)
4997 <p>You can specify as many of these components as needed in any order (e.g.
4998 bgr). The components can repeat as well (e.g. rgbr).</p>
5001 <div style="margin: auto;">
5002 <h4><a id="mask"></a>-mask
5003 <em class="arg">filename</em></h4>
5006 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Prevent updates to image pixels specified by the mask.</td><td style='text-align:right;'></td></tr></table>
5008 <p>This the same as using a mask used for composite masking operations, with
5009 grayscale values causing blended updates of the image the mask is attached to.
5012 <p>Use <a href="command-line-options.html#mask">+mask</a> to remove the mask from images.</p>
5014 <p>Also see <a href="command-line-options.html#clip-mask">-clip-mask</a> which work in the same way,
5015 but with strict boolean masking. </p>
5017 <div style="margin: auto;">
5018 <h4><a id="mattecolor"></a>-mattecolor <em class="arg">color</em></h4>
5021 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the color to be used with the <a href="command-line-options.html#frame">-frame</a> option.</td><td style='text-align:right;'></td></tr></table>
5023 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
5025 <p>The default matte color is <kbd>#BDBDBD</kbd>, <span
5026 style="background-color: #bdbdbd;">this shade of gray</span>.</p>
5028 <div style="margin: auto;">
5029 <h4><a id="maximum"></a>-maximum</h4>
5032 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>return the maximum intensity of an image sequence.</td><td style='text-align:right;'></td></tr></table>
5034 <p>Select the 'maximum' value from all the surrounding pixels. </p>
5036 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</A> of the same
5039 <div style="margin: auto;">
5040 <h4><a id="median"></a>-median <em class="arg">geometry</em></h4>
5043 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a median filter to the image.</td><td style='text-align:right;'></td></tr></table>
5045 <p>Select the 'middle' value from all the surrounding pixels. </p>
5047 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</A> of the same
5050 <div style="margin: auto;">
5051 <h4><a id="metric"></a>-metric <em class="arg">type</em></h4>
5054 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Output to STDERR a measure of the differences between images according to the <em class="arg">type</em> given metric.</td><td style='text-align:right;'></td></tr></table>
5059 AE absolute error count, number of different pixels (-fuzz effected)
5060 FUZZ mean color distance
5061 MAE mean absolute error (normalized), average channel error distance
5062 MEPP mean error per pixel (normalized mean error, normalized peak error)
5063 MSE mean error squared, average of the channel error squared
5064 NCC normalized cross correlation
5065 PAE peak absolute (normalize peak absolute)
5066 PSNR peak signal to noise ratio
5067 RMSE root mean squared (normalized root mean squared)
5070 <p>Control the '<kbd>AE</kbd>', or absolute count of pixels that are different,
5071 with the <a href="command-line-options.html#fuzz" >-fuzz</a> factor (ignore pixels which
5072 only changed by a small amount). Use '<kbd>PAE</kbd>' to find the
5073 size of the <a href="command-line-options.html#fuzz" >-fuzz</a> factor needed to make all pixels
5074 'similar', while '<kbd>MAE</kbd>' determines the factor needed
5075 for about half the pixels to be similar. </p>
5077 <p>The '<kbd>MEPP</kbd>' metric returns three different metrics
5078 ('<kbd>MAE</kbd>', '<kbd>MAE</kbd>' normalized, and '<kbd>PAE</kbd>'
5079 normalized) from a single comparison run. </p>
5081 <p>To print a complete list of metrics, use the <a href="command-line-options.html#list">-list
5082 metrics</a> option.</p>
5085 <div style="margin: auto;">
5086 <h4><a id="minimum"></a>-minimum</h4>
5089 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>return the minimum intensity of an image sequence.</td><td style='text-align:right;'></td></tr></table>
5091 <p>Select the 'minimal' value from all the surrounding pixels. </p>
5093 <p>This is legacy option from the <a href="command-line-options.html#statistic" >method</A> of the same
5098 <div style="margin: auto;">
5099 <h4><a id="mode"></a>-mode <em class="arg">geometry</em></h4>
5102 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>make each pixel the 'predominant color' of the neighborhood.</td><td style='text-align:right;'>[<a href="convert.html">convert</a>, <a href="mogrify.html">mogrify</a>]</td></tr></table>
5104 <div style="margin: auto;">
5105 <h4>-mode <em class="arg">value</em></h4>
5108 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mode of operation.</td><td style='text-align:right;'>[<a href="montage.html">montage</a>]</td></tr></table>
5110 <p>Choose the <em class="arg">value</em> from these styles: <kbd>Frame,
5111 Unframe, or Concatenate</kbd></p>
5113 <p>Use the <a href="command-line-options.html#list" >-list</a> option with a '<kbd>Mode</kbd>' argument
5114 for a list of <a href="command-line-options.html#mode" >-mode</a> arguments available in your
5115 ImageMagick installation.</p>
5118 <div style="margin: auto;">
5119 <h4><a id="modulate"></a>-modulate <em class="arg">brightness</em>[,<em class="arg">saturation</em>,<em class="arg">hue</em>]</h4>
5122 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Vary the <em class="arg">brightness</em>, <em
5123 class="arg">saturation</em>, and <em class="arg">hue</em> of an image.</td><td style='text-align:right;'></td></tr></table>
5125 <p>The arguments are given as a percentages of variation. A value of 100 means
5126 no change, and any missing values are taken to mean 100.</p>
5128 <p>The <em class="arg">brightness</em> is a multiplier of the overall
5129 brightness of the image, so 0 means pure black, 50 is half as bright, 200 is
5130 twice as bright. To invert its meaning <a href="command-line-options.html#negate">-negate</a> the image
5131 before and after. </p>
5133 <p>The <em class="arg">saturation</em> controls the amount of color in an
5134 image. For example, 0 produce a grayscale image, while a large value such as
5135 200 produce a very colorful, 'cartoonish' color.</p>
5137 <p>The <em class="arg">hue</em> argument causes a "rotation" of the colors
5138 within the image by the amount specified. For example, 50 results in
5139 a counter-clockwise rotation of 90, mapping red shades to purple, and so on.
5140 A value of either 0 or 200 results in a complete 180 degree rotation of the
5141 image. Using a value of 300 is a 360 degree rotation resulting in no change to
5142 the original image. </p>
5144 <p>For example, to increase the color brightness by 20% and decrease the color
5145 saturation by 10% and leave the hue unchanged, use <a
5146 href="command-line-options.html#modulate">-modulate 120,90</a>.</p>
5148 <p>Use <a href="command-line-options.html#set">-set</a> attribute of '<kbd
5149 class="arg">option:modulate:colorspace</kbd>' to specify which colorspace to
5150 modulate. Choose from <kbd>HSB</kbd>, <kbd>HSL</kbd> (the default), or
5151 <kbd>HWB</kbd>. For example,</p>
5153 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png</span></p>
5155 <div style="margin: auto;">
5156 <h4><a id="monitor"></a>-monitor</h4>
5159 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>monitor progress.</td><td style='text-align:right;'></td></tr></table>
5162 <div style="margin: auto;">
5163 <h4><a id="monochrome"></a>-monochrome</h4>
5166 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>transform the image to black and white.</td><td style='text-align:right;'></td></tr></table>
5168 <div style="margin: auto;">
5169 <h4><a id="morph"></a>-morph <em class="arg">frames</em></h4>
5172 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>morphs an image sequence.</td><td style='text-align:right;'></td></tr></table>
5174 <p>Both the image pixels and size are linearly interpolated to give the
5175 appearance of a metamorphosis from one image to the next, over all the images
5176 in the current image list. The added images are the equivalent of a <a
5177 href="command-line-options.html#blend">-blend</a> composition. The <em class="arg">frames</em>
5178 argument determine how many images to interpolate between each image. </p>
5181 <div style="margin: auto;">
5182 <h4><a id="morphology"></a>-morphology</h4>
5183 <h4>-morphology <em class="arg">method</em> <em class="arg">kernel</em></h4>
5186 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>apply a morphology method to the image.</td><td style='text-align:right;'></td></tr></table>
5188 <p>Until I get around to writing an option summary for this, see <a
5189 href="http://www.imagemagick.org/Usage/morphology/" >IM Usage Examples,
5190 Morphology</a>. </p>
5193 <div style="margin: auto;">
5194 <h4><a id="mosaic"></a>-mosaic</h4>
5197 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>an simple alias for the <a href="command-line-options.html#layers" >-layers</a> method "mosaic"</td><td style='text-align:right;'></td></tr></table>
5200 <div style="margin: auto;">
5201 <h4><a id="motion-blur"></a>-motion-blur <em class="arg">radius</em><br />-motion-blur <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">angle</em>+<em class="arg">bias</em></h4>
5204 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate motion blur.</td><td style='text-align:right;'></td></tr></table>
5206 <p>Blur with the given radius, standard deviation (sigma), and angle. The
5207 angle given is the angle toward which the image is blurred. That is the
5208 direction people would consider the object is coming from. </p>
5210 <p>Note that the blur is not uniform distribution, giving the motion a
5211 definite sense of direction of movement. </p>
5213 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5214 pixels which are outside the image proper are blurred into the final result.
5217 <div style="margin: auto;">
5218 <h4><a id="name"></a>-name</h4>
5221 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>name an image.</td><td style='text-align:right;'></td></tr></table>
5222 <div style="margin: auto;">
5223 <h4><a id="negate"></a>-negate</h4>
5226 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>replace each pixel with its complementary color.</td><td style='text-align:right;'></td></tr></table>
5228 <p>The red, green, and blue intensities of an image are negated. White becomes
5229 black, yellow becomes blue, etc. Use <a href="command-line-options.html#negate">+negate</a> to only
5230 negate the grayscale pixels of the image.</p>
5232 <div style="margin: auto;">
5233 <h4><a id="noise"></a>-noise <em class="arg">geometry</em><br/>
5234 +noise <em class="arg">type</em></h4>
5237 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Add or reduce noise in an image.</td><td style='text-align:right;'></td></tr></table>
5239 <p>The principal function of noise peak elimination filter is to smooth the
5240 objects within an image without losing edge information and without creating
5241 undesired structures. The central idea of the algorithm is to replace a pixel
5242 with its next neighbor in value within a pixel window, if this pixel has been
5243 found to be noise. A pixel is defined as noise if and only if this pixel is
5244 a maximum or minimum within the pixel window.</p>
5246 <p>Use <kbd><a href="command-line-options.html#noise">-noise</a> <em class="arg">radius</em></kbd> to
5247 specify the width of the neighborhood when reducing noise. This is equivelent
5248 to using a <kbd><a href="command-line-options.html#statistic" >-statistic</a> NonPeak</kbd> operation,
5249 which should be used in preference.</p>
5251 <p>Use <a href="command-line-options.html#noise">+noise</a> followed by a noise <em
5252 class="arg">type</em> to add noise to an image. Choose from these noise
5265 <p>The amount of noise added can be controled by the <kbd><a
5266 href="command-line-options.html#attunuuate" >-attenuate</a></kbd> setting. If unset the value is
5267 equivelent to 1.0, or a maximum noise addition.</p>
5269 <p>To print a complete list of noises, use the <a href="command-line-options.html#list">-list noise</a> option.</p>
5271 <p>Also see the <a href="command-line-options.html#evaluate">-evaluate</a> noise functions that allows
5272 the use of a controlling value to specify the amount of noise that should be
5273 added to an image. </p>
5276 <div style="margin: auto;">
5277 <h4><a id="normalize"></a>-normalize</h4>
5280 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Increase the contrast in an image by <em>stretching</em> the range of intensity values.</td><td style='text-align:right;'></td></tr></table>
5282 <p>The intensity values are stretched to cover the entire range of possible
5283 values. While doing so, black-out at most <em>2%</em> of the pixels and
5284 white-out at most <em>1%</em> of the pixels.</p>
5286 <p>Note that as of ImageMagick 6.4.7-0, <a href="command-line-options.html#normalize" >-normalize</a>
5287 is equivalent to <a href="command-line-options.html#contrast-stretch" >-contrast-stretch 2%x1%</a>.
5288 (Before this version, it was equivalent to <a href="command-line-options.html#contrast-stretch"
5289 >-contrast-stretch 2%x99%</a>).</p>
5291 <p>All the channels are normalized in concert by the came amount so as to
5292 preserve color integrity, when the default <a href="command-line-options.html#channel" >+channel</a>
5293 setting is in use. Specifying any other <a href="command-line-options.html#channel" >-channel</a>
5294 setting will normalize the RGB channels independently.</p>
5296 <p>See <a href="command-line-options.html#contrast-stretch" >-contrast-stretch</a> for more details.
5297 Also see <a href="command-line-options.html#auto-level" >-auto-level</a> for a 'perfect' normalization
5298 that is better suited to mathematically generated images. </p>
5300 <p>This operator is under review for re-development. </p>
5303 <div style="margin: auto;">
5304 <h4><a id="ordered-dither"></a>-ordered-dither <em class="arg">threshold_map</em>{,<em class="arg">level</em>...}</h4>
5307 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>dither the image using a pre-defined ordered dither <em
5308 class="arg">threshold map</em> specified, and a uniform color map with the
5309 given number of <em class="arg">levels</em> per color channel . </td><td style='text-align:right;'></td></tr></table>
5311 <p>You can choose from these standard threshold maps:</p>
5314 threshold 1x1 Threshold 1x1 (non-dither)
5315 checks 2x1 Checkerboard 2x1 (dither)
5316 o2x2 2x2 Ordered 2x2 (dispersed)
5317 o3x3 3x3 Ordered 3x3 (dispersed)
5318 o4x4 4x4 Ordered 4x4 (dispersed)
5319 o8x8 8x8 Ordered 8x8 (dispersed)
5320 h4x4a 4x1 Halftone 4x4 (angled)
5321 h6x6a 6x1 Halftone 6x6 (angled)
5322 h8x8a 8x1 Halftone 8x8 (angled)
5323 h4x4o Halftone 4x4 (orthogonal)
5324 h6x6o Halftone 6x6 (orthogonal)
5325 h8x8o Halftone 8x8 (orthogonal)
5326 h16x16o Halftone 16x16 (orthogonal)
5327 c5x5b c5x5 Circles 5x5 (black)
5328 c5x5w Circles 5x5 (white)
5329 c6x6b c6x6 Circles 6x6 (black)
5330 c6x6w Circles 6x6 (white)
5331 c7x7b c7x7 Circles 7x7 (black)
5332 c7x7w Circles 7x7 (white)
5335 <p> The <kbd>threshold</kbd> generated a simple 50% threshold of the image.
5336 This could be used with <em class="arg" >level</em> to do the equivalent of <a
5337 href="command-line-options.html#posterize" >-posterize</a> to reduce an image to basic primary colors.
5340 <p>The <kbd>checks</kbd> pattern produces a 3 level checkerboard dither
5341 pattern. That is a grayscale will become a pattern of solid black, solid
5342 white, and mid-tone colors into a checkerboard pattern of black and white.
5345 <p>You can define your own <em class="arg" >threshold map</em> for ordered
5346 dithering and halftoning your images, in either personal or system
5347 <kbd>thresholds.xml</kbd> XML file. See <a href="resources.html" >Resources</A>
5348 for more details of configuration files. </p>
5350 <p>To print a complete list of the thresholds that have been defined, use the
5351 <a href="command-line-options.html#list" >-list threshold</a> option.</p>
5353 <p>Note that at this time the same threshold dithering map is used for all
5354 color channels, no attempt is made to offset or rotate the map for different
5355 channels is made, to create an offset printing effect. Also as the maps are
5356 simple threshold levels, the halftone and circle maps will create incomplete
5357 circles along the edges of a colored area. Also all the effects are purely
5358 on/off boolean effects, without anti-aliasing to make the circles smooth
5359 looking. Large dots can be made to look better with a small amount of blurring
5360 after being created. </p>
5363 <div style="margin: auto;">
5364 <h4><a id="opaque"></a>-opaque <em class="arg">color</em></h4>
5367 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>change this color to the fill color within the image.</td><td style='text-align:right;'></td></tr></table>
5369 <p>The <em class="arg">color</em> argument is defined using the format
5370 described under the <a href="command-line-options.html#fill" >-fill</a> option. The <a href="command-line-options.html#fuzz"
5371 >-fuzz</a> setting can be used to match and replace colors similar to the one
5374 <p>Use <a href="command-line-options.html#opaque">+opaque</a> to paint any pixel that does not match
5375 the target color. </p>
5377 <p>The <a href="command-line-options.html#transparent">-transparent</a> operator is exactly the same
5378 as <a href="command-line-options.html#opaque" >-opaque</a> but replaces the matching color with
5379 transparency rather than the current <a href="command-line-options.html#fill">-fill</a> color setting.
5380 To ensure that it can do this it also ensures that the image has an alpha
5381 channel enabled, as per "<kbd><a href="command-line-options.html#alpha" >-alpha</a> set</kbd>", for
5382 the new transparent colors, and does not require you to modify the <a
5383 href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
5386 <div style="margin: auto;">
5387 <h4><a id="orient"></a>-orient <em class="arg">image orientation</em></h4>
5390 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify orientation of a digital camera image.</td><td style='text-align:right;'></td></tr></table>
5392 <p>Choose from these orientations:</p>
5406 <p>To print a complete list of orientations, use the <a href="command-line-options.html#list" >-list
5407 orientation</a> option.</p>
5410 <div style="margin: auto;">
5411 <h4><a id="page"></a>-page <em class="arg">geometry</em><br/>
5412 -page <em class="arg">media</em>[<em class="arg">offset</em>][{<em class="arg">^!<></em>}]<br/>
5417 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the size and location of an image on the larger virtual canvas.</td><td style='text-align:right;'></td></tr></table>
5419 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5421 <p>For convenience you can specify the page size using <em
5422 class="arg">media</em> (see below). Offsets can then be added as with other
5423 <em class="arg">geometry</em> arguments (e.g. <a
5424 href="command-line-options.html#page">-page</a> <kbd>Letter+43+43</kbd>).</p>
5426 <p>Use <em class="arg">media</em> as shorthand to specify the dimensions (<em
5427 class="arg">width</em>x<em class="arg">height</em>) of the <em
5428 class="arg">PostScript</em> page in dots per inch or a TEXT page in pixels.
5429 The choices for a PostScript page are:</p>
5431 <table id="geometryTable" cellpadding="2" cellspacing="0" border="1"
5432 width="50%" style="margin-left: auto; margin-right: auto;">
5435 <th align="center"><em class="arg">media</em></th>
5436 <th align="center"><em class="arg">width</em></th>
5437 <th align="center"><em class="arg">height</em></th>
5441 <tr><td align="left"> 11x17 </td> <td align="right"> 792</td> <td align="right"> 1224</td> </tr>
5442 <tr><td align="left"> Ledger </td> <td align="right"> 1224</td> <td align="right"> 792</td> </tr>
5443 <tr><td align="left"> Legal </td> <td align="right"> 612</td> <td align="right"> 1008</td> </tr>
5444 <tr><td align="left"> Letter </td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
5445 <tr><td align="left"> LetterSmall</td> <td align="right"> 612</td> <td align="right"> 792</td> </tr>
5446 <tr><td align="left"> ArchE </td> <td align="right"> 2592</td> <td align="right"> 3456</td> </tr>
5447 <tr><td align="left"> ArchD </td> <td align="right"> 1728</td> <td align="right"> 2592</td> </tr>
5448 <tr><td align="left"> ArchC </td> <td align="right"> 1296</td> <td align="right"> 1728</td> </tr>
5449 <tr><td align="left"> ArchB </td> <td align="right"> 864</td> <td align="right"> 1296</td> </tr>
5450 <tr><td align="left"> ArchA </td> <td align="right"> 648</td> <td align="right"> 864</td> </tr>
5451 <tr><td align="left"> A0 </td> <td align="right"> 2380</td> <td align="right"> 3368</td> </tr>
5452 <tr><td align="left"> A1 </td> <td align="right"> 1684</td> <td align="right"> 2380</td> </tr>
5453 <tr><td align="left"> A2 </td> <td align="right"> 1190</td> <td align="right"> 1684</td> </tr>
5454 <tr><td align="left"> A3 </td> <td align="right"> 842</td> <td align="right"> 1190</td> </tr>
5455 <tr><td align="left"> A4 </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
5456 <tr><td align="left"> A4Small </td> <td align="right"> 595</td> <td align="right"> 842</td> </tr>
5457 <tr><td align="left"> A5 </td> <td align="right"> 421</td> <td align="right"> 595</td> </tr>
5458 <tr><td align="left"> A6 </td> <td align="right"> 297</td> <td align="right"> 421</td> </tr>
5459 <tr><td align="left"> A7 </td> <td align="right"> 210</td> <td align="right"> 297</td> </tr>
5460 <tr><td align="left"> A8 </td> <td align="right"> 148</td> <td align="right"> 210</td> </tr>
5461 <tr><td align="left"> A9 </td> <td align="right"> 105</td> <td align="right"> 148</td> </tr>
5462 <tr><td align="left"> A10 </td> <td align="right"> 74</td> <td align="right"> 105</td> </tr>
5463 <tr><td align="left"> B0 </td> <td align="right"> 2836</td> <td align="right"> 4008</td> </tr>
5464 <tr><td align="left"> B1 </td> <td align="right"> 2004</td> <td align="right"> 2836</td> </tr>
5465 <tr><td align="left"> B2 </td> <td align="right"> 1418</td> <td align="right"> 2004</td> </tr>
5466 <tr><td align="left"> B3 </td> <td align="right"> 1002</td> <td align="right"> 1418</td> </tr>
5467 <tr><td align="left"> B4 </td> <td align="right"> 709</td> <td align="right"> 1002</td> </tr>
5468 <tr><td align="left"> B5 </td> <td align="right"> 501</td> <td align="right"> 709</td> </tr>
5469 <tr><td align="left"> C0 </td> <td align="right"> 2600</td> <td align="right"> 3677</td> </tr>
5470 <tr><td align="left"> C1 </td> <td align="right"> 1837</td> <td align="right"> 2600</td> </tr>
5471 <tr><td align="left"> C2 </td> <td align="right"> 1298</td> <td align="right"> 1837</td> </tr>
5472 <tr><td align="left"> C3 </td> <td align="right"> 918</td> <td align="right"> 1298</td> </tr>
5473 <tr><td align="left"> C4 </td> <td align="right"> 649</td> <td align="right"> 918</td> </tr>
5474 <tr><td align="left"> C5 </td> <td align="right"> 459</td> <td align="right"> 649</td> </tr>
5475 <tr><td align="left"> C6 </td> <td align="right"> 323</td> <td align="right"> 459</td> </tr>
5476 <tr><td align="left"> Flsa </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
5477 <tr><td align="left"> Flse </td> <td align="right"> 612</td> <td align="right"> 936</td> </tr>
5478 <tr><td align="left"> HalfLetter </td> <td align="right"> 396</td> <td align="right"> 612</td> </tr>
5483 <p>This option is also used to place subimages when writing to a multi-image
5484 format that supports offsets, such as GIF89 and MNG. When used for this
5485 purpose the offsets are always measured from the top left corner of the canvas
5486 and are not affected by the <a href="command-line-options.html#gravity">-gravity</a> option. To
5487 position a GIF or MNG image, use <a href="command-line-options.html#page">-page</a><em
5488 class="arg">{+-}x{+-}y</em> (e.g. -page +100+200). When writing to a MNG
5489 file, a <a href="command-line-options.html#page">-page</a> option appearing ahead of the first image in
5490 the sequence with nonzero width and height defines the width and height values
5491 that are written in the <kbd>MHDR</kbd> chunk. Otherwise, the MNG width and
5492 height are computed from the bounding box that contains all images in the
5493 sequence. When writing a GIF89 file, only the bounding box method is used to
5494 determine its dimensions.</p>
5496 <p>For a PostScript page, the image is sized as in <a
5497 href="command-line-options.html#geometry">-geometry</a> but positioned relative to the <em>lower
5498 left-hand corner</em> of the page by {+-}<kbd>x</kbd><em
5499 class="arg">offset</em>{+-}<kbd>y</kbd> <em class="arg">offset</em>. Use <a
5500 href="command-line-options.html#page">-page 612x792</a>, for example, to center the image within the
5501 page. If the image size exceeds the PostScript page, it is reduced to fit the
5502 page. The default gravity for the <a href="command-line-options.html#page">-page</a> option is <em
5503 class="arg">NorthWest</em>, i.e., positive <kbd>x</kbd> and <kbd>y</kbd> <em
5504 class="arg">offset</em> are measured rightward and downward from the top left
5505 corner of the page, unless the <a href="command-line-options.html#gravity">-gravity</a> option is
5506 present with a value other than <em class="arg">NorthWest</em>.</p>
5508 <p>The default page dimensions for a TEXT image is 612x792.</p>
5510 <p>This option is used in concert with <a href="command-line-options.html#density">-density</a>.</p>
5512 <p>Use <a href="command-line-options.html#page">+page</a> to remove the page settings for an image.</p>
5514 <div style="margin: auto;">
5515 <h4><a id="paint"></a>-paint <em class="arg">radius</em></h4>
5518 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate an oil painting.</td><td style='text-align:right;'></td></tr></table>
5520 <p>Each pixel is replaced by the most frequent color in a circular
5521 neighborhood whose width is specified with <em class="arg">radius</em>.</p>
5523 <div style="margin: auto;">
5524 <h4><a id="path"></a>-path <em class="arg">path</em></h4></div>
5526 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>write images to this path on disk.</td><td style='text-align:right;'></td></tr></table>
5528 <div style="margin: auto;">
5529 <h4><a id="pause_animate_"></a>-pause <em class="arg">seconds</em></h4>
5532 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pause between animation loops.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>]</td></tr></table>
5534 <p>Pause for the specified number of seconds before repeating the animation.</p>
5536 <div style="margin: auto;">
5537 <h4><a id="pause_import_"></a>-pause <em class="arg">seconds</em></h4>
5540 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pause between snapshots.</td><td style='text-align:right;'>[<a href="import.html">import</a>]</td></tr></table>
5542 <p>Pause for the specified number of seconds before taking the next snapshot.</p>
5544 <div style="margin: auto;">
5545 <h4><a id="ping"></a>-ping</h4>
5548 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>efficiently determine image characteristics.</td><td style='text-align:right;'></td></tr></table>
5550 <div style="margin: auto;">
5551 <h4><a id="pointsize"></a>-pointsize <em class="arg">value</em></h4>
5554 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pointsize of the PostScript, OPTION1, or TrueType font.</td><td style='text-align:right;'></td></tr></table>
5556 <div style="margin: auto;">
5557 <h4><a id="polaroid"></a>-polaroid <em class="arg">angle</em></h4>
5560 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a Polaroid picture.</td><td style='text-align:right;'></td></tr></table>
5562 <p>Use <kbd>+polaroid</kbd> to rotate the image at a random angle between -15 and +15 degrees.</p>
5564 <div style="margin: auto;">
5565 <h4><a id="posterize"></a>-posterize <em class="arg">levels</em></h4>
5568 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce the image to a limited number of color levels.</td><td style='text-align:right;'></td></tr></table>
5570 <div style="margin: auto;">
5571 <h4><a id="precision"></a>-precision <em class="arg">value</em></h4>
5574 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the maximum number of significant digits to be printed.</td><td style='text-align:right;'></td></tr></table>
5576 <div style="margin: auto;">
5577 <h4><a id="preview"></a>-preview <em class="arg">type</em></h4>
5580 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>image preview type.</td><td style='text-align:right;'></td></tr></table>
5582 <p>Use this option to affect the preview operation of an image (e.g.
5583 <kbd>convert file.png -preview Gamma Preview:gamma.png</kbd>). Choose from
5587 Rotate Shear Roll Hue
5588 Saturation Brightness Gamma Spiff
5589 Dull Grayscale Quantize Despeckle
5590 ReduceNoise Add Noise Sharpen Blur
5591 Threshold EdgeDetect Spread Shade
5592 Raise Segment Solarize Swirl
5593 Implode Wave OilPaint CharcoalDrawing
5597 <p>To print a complete list of previews, use the <a href="command-line-options.html#list">-list preview</a> option.</p>
5599 <p>The default preview is <kbd>JPEG</kbd>.</p>
5601 <div style="margin: auto;">
5602 <h4><a id="print"></a>-print <em class="arg">string</em></h4>
5605 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>interpret string and print to console.</td><td style='text-align:right;'></td></tr></table>
5607 <div style="margin: auto;">
5608 <h4><a id="process"></a>-process <em class="arg">command</em></h4>
5611 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>process the image with a custom image filter.</td><td style='text-align:right;'></td></tr></table>
5613 <p>The command arguments has the form <kbd>"module arg1 arg2 arg3 ...
5614 argN"</kbd> where <kbd>module</kbd> is the name of the module to invoke (e.g.
5615 "Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to
5616 pass to the process module.</p>
5618 <div style="margin: auto;">
5619 <h4><a id="profile"></a>-profile <em class="arg">filename</em><br/>
5620 +profile <em class="arg">profile_name</em></h4>
5623 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Manage ICM, IPTC, or generic profiles in an image.</td><td style='text-align:right;'></td></tr></table>
5625 <p>Using <a href="command-line-options.html#profile">-profile</a> <em class="arg">filename</em> adds an
5626 ICM (ICC color management), IPTC (newswire information), or a generic profile
5629 <p>Use <a href="command-line-options.html#profile">+profile <em class="arg">profile_name</em></a> to
5630 remove the indicated profile. ImageMagick uses standard filename globbing, so
5631 wildcard expressions may be used to remove more than one profile. Here we
5632 remove all profiles from the image except for the XMP profile: <kbd>+profile
5633 "!xmp,*"</kbd>. </p>
5635 <p>Use <kbd>identify -verbose</kbd> to find out which profiles are in the
5636 image file. Use <a href="command-line-options.html#strip">-strip</a> to remove all profiles (and
5639 <p>To extract a profile, the <a href="command-line-options.html#profile">-profile</a> option is not
5640 used. Instead, simply write the file to an image format such as <em
5641 class="arg">APP1, 8BIM, ICM,</em> or <em class="arg">IPTC</em>.</p>
5643 <p>For example, to extract the Exif data (which is stored in JPEG files in the
5644 <em class="arg">APP1</em> profile), use.</p>
5646 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert cockatoo.jpg profile.exif</span></p>
5647 <p>It is important to note that results may depend on whether or not the
5648 original image already has an included profile. Also, keep in mind that <a
5649 href="command-line-options.html#profile">-profile</a> is an "operator" (as opposed to a "setting") and
5650 therefore a conversion is made each time it is encountered, in order, in the
5651 command-line. For instance, in the following example, if the original image is
5652 CMYK with profile, a CMYK-CMYK-RGB conversion results.</p>
5654 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff</span></p>
5655 <p>Furthermore, since ICC profiles are not necessarily symmetric, extra
5656 conversion steps can yield unwanted results. CMYK profiles are often very
5657 asymmetric since they involve 3−>4 and 4−>3 channel mapping.
5660 <div style="margin: auto;">
5661 <h4><a id="quality"></a>-quality <em class="arg">value</em></h4>
5664 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>JPEG/MIFF/PNG compression level.</td><td style='text-align:right;'></td></tr></table>
5666 <p>For the JPEG and MPEG image formats, quality is 1 (lowest image quality and
5667 highest compression) to 100 (best quality but least effective compression).
5668 The default is to use the estimated quality of your input image if it can
5669 be determined, otherwise 92. When the quality is greater than 90, then the
5670 chroma channels are not downsampled.
5671 Use the <a href="command-line-options.html#sampling-factor">-sampling-factor</a> option to specify the
5672 factors for chroma downsampling.</p>
5674 <p>For the MIFF image format, quality/10 is the zlib compression level, which
5675 is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect
5676 on the image appearance, since the compression is always lossless.</p>
5678 <p>For the JPEG-2000 image format, quality is mapped using a non-linear
5679 equation to the compression ratio required by the Jasper library. This
5680 non-linear equation is intended to loosely approximate the quality provided by
5681 the JPEG v1 format. The default quality value 100, a request for non-lossy
5682 compression. A quality of 75 results in a request for 16:1 compression.</p>
5684 <p>For the MNG and PNG image formats, the quality value sets the zlib
5685 compression level (quality / 10) and filter-type (quality % 10). The default
5686 PNG "quality" is 75, which means compression level 7 with adaptive PNG
5687 filtering, unless the image has a color map, in which case it means
5688 compression level 7 with no PNG filtering.</p>
5690 <p>For compression level 0, the Huffman-only strategy is used, which is
5691 fastest but not necessarily the worst compression.</p>
5693 <p>If filter-type is 4 or less, the specified PNG filter-type is used for
5704 <p>If filter-type is 5, adaptive filtering is used when quality is greater
5705 than 50 and the image does not have a color map, otherwise no filtering is
5708 <p>If filter-type is 6, adaptive filtering
5709 with <em class="arg">minimum-sum-of-absolute-values</em> is used.</p>
5711 <p>Only if the output is MNG, if filter-type is 7, the LOCO color
5712 transformation (intrapixel differencing) and adaptive filtering
5713 with <em class="arg">minimum-sum-of-absolute-values</em> are used.</p>
5715 <p>If the filter-type is 8 the zlib Z_RLE compression strategy is used with
5716 no PNG filtering.</p>
5718 <p>If the filter-type is 9 the zlib Z_RLE compression strategy is used with
5719 adaptive PNG filtering.</p>
5721 <p>The quality setting has no effect on the appearance or signature of PNG
5722 and MNG images, since the compression is always lossless.</p>
5724 <p>Not all combinations of compression level, strategy, and PNG filter type
5725 can be obtained using the -quality option. For more precise control,
5726 you can use the PNG:compression-level=N, PNG:compression-strategy=N, and
5727 PNG:compression-filter=N defines, respectively, instead.
5728 See <a href="command-line-options.html#define">-define</a>. Values from the defines take precedence
5729 over values from the -quality option.</p>
5731 <p>For further information, see
5732 the <a href="http://www.w3.org/pub/WWW/TR">PNG</a> specification.</p>
5734 <div style="margin: auto;">
5735 <h4><a id="quantize"></a>-quantize <em class="arg">colorspace</em></h4>
5738 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>reduce colors using this colorspace.</td><td style='text-align:right;'></td></tr></table>
5740 <p>This setting defines the colorspace used to sort out and reduce the number
5741 of colors needed by an image (for later dithering) by operators such as <a
5742 href="command-line-options.html#colors" >-colors</a>, Note that color reduction also happens
5743 automatically when saving images to color-limited image file formats, such as
5747 <div style="margin: auto;">
5748 <h4><a id="quiet"></a>-quiet</h4>
5751 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>suppress all warning messages. Error messages are still reported.</td><td style='text-align:right;'></td></tr></table>
5753 <div style="margin: auto;">
5754 <h4><a id="radial-blur"></a>-radial-blur <em class="arg">angle</em></h4>
5757 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Blur around the center of the image.</td><td style='text-align:right;'></td></tr></table>
5759 <p>Note that this is actually a rotational blur rather than a radial and as
5760 such actually mis-named. </p>
5762 <p>The <a href="command-line-options.html#virtual-pixel">-virtual-pixel</a> setting will determine how
5763 pixels which are outside the image proper are blurred into the final result.
5767 <div style="margin: auto;">
5768 <h4><a id="raise"></a>-raise <em class="arg">thickness</em></h4>
5771 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Lighten or darken image edges.</td><td style='text-align:right;'></td></tr></table>
5773 <p>This will create a 3-D effect. Use <a href="command-line-options.html#raise">-raise</a> to create
5774 a raised effect, otherwise use <a href="command-line-options.html#raise">+raise</a>. </p>
5776 <p>Unlike the similar <a href="command-line-options.html#frame">-frame</a> option, <a
5777 href="command-line-options.html#raise">-raise</a> does not alter the dimensions of the image.</p>
5779 <div style="margin: auto;">
5780 <h4><a id="random-threshold"></a>-random-threshold <em class="arg">low</em>x<em class="arg">high</em></h4>
5783 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply a random threshold to the image.</td><td style='text-align:right;'></td></tr></table>
5785 <div style="margin: auto;">
5786 <h4><a id="red-primary"></a>-red-primary <em class="arg">x,y</em></h4>
5789 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the red chromaticity primary point.</td><td style='text-align:right;'></td></tr></table>
5791 <div style="margin: auto;">
5792 <h4><a id="regard-warnings"></a>-regard-warnings</h4>
5795 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Pay attention to warning messages.</td><td style='text-align:right;'></td></tr></table>
5797 <div style="margin: auto;">
5798 <h4><a id="remap"></a>-remap <em class="arg">filename</em></h4>
5801 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reduce the number of colors in an image to the colors used by this image.</td><td style='text-align:right;'></td></tr></table>
5803 <p>If the <a href="command-line-options.html#dither">-dither</a> setting is enabled (the default) then
5804 the given colors are dithered over the image as necessary, otherwise the closest
5805 color (in RGB colorspace) is selected to replace that pixel in the image. </p>
5807 <p>As a side effect of applying a <a href="command-line-options.html#remap">-remap</a> of colors across all
5808 images in the current image sequence, all the images will have the same color
5809 table. That means that when saved to a file format such as GIF, it will use
5810 that color table as a single common or global color table, for all the images,
5811 without requiring extra local color tables. </p>
5813 <p>Use <a href="command-line-options.html#remap">+remap</a> to reduce all images in the current image
5814 sequence to use a common color map over all the images. This equivalent to
5815 appending all the images together (without extra background colors) and color
5816 reducing those images using <a href="command-line-options.html#colors">-colors</a> with a 256 color
5817 limit, then <a href="command-line-options.html#remap">-remap</a> those colors over the original list of
5818 images. This ensures all the images follow a single color map. </p>
5820 <p>If the number of colors over all the images is less than 256, then <a
5821 href="command-line-options.html#remap">+remap</a> should not perform any color reduction or dithering, as
5822 no color changes are needed. In that case, its only effect is to force the use
5823 of a global color table. This recommended after using either <a
5824 href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#ordered-dither">-ordered-dither</a> to
5825 reduce the number of colors in an animated image sequence. </p>
5827 <div style="margin: auto;">
5828 <h4><a id="region"></a>-region <em class="arg">geometry</em></h4>
5831 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a region in which subsequent operations apply.</td><td style='text-align:right;'></td></tr></table>
5833 <p>The <em class="arg">x</em> and <em class="arg">y</em> offsets are treated
5834 in the same manner as in <a href="command-line-options.html#crop">-crop</a>.</p>
5836 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5838 <div style="margin: auto;">
5839 <h4><a id="remote"></a>-remote</h4>
5842 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>perform a remote operation.</td><td style='text-align:right;'></td></tr></table>
5844 <p>The only command recognized is the name of an image file to load.</p>
5846 <p>If you have more than one <a href="display.html">display</a> application
5847 running simultaneously, use the <a href="command-line-options.html#window"> window</a> option to
5848 specify which application to control.</p>
5850 <div style="margin: auto;">
5851 <h4><a id="render"></a>-render</h4>
5854 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>render vector operations.</td><td style='text-align:right;'></td></tr></table>
5856 <p>Use <a href="command-line-options.html#render">+render</a> to turn off rendering vector operations.
5857 This useful when saving the result to vector formats such as MVG or SVG.</p>
5859 <div style="margin: auto;">
5860 <h4><a id="repage"></a>-repage <em class="arg">geometry</em></h4>
5863 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Adjust the canvas and offset information of the image.</td><td style='text-align:right;'></td></tr></table>
5865 <p>This option is like <a href="command-line-options.html#page">-page</a> but acts as an image operator
5866 rather than a setting. You can separately set the canvas size or the offset
5867 of the image on that canvas by only providing those components. </p>
5869 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
5871 <p>If a <kbd>!</kbd> flag is given the offset given is added to the existing
5872 offset to move the image relative to its previous position. This useful for
5873 animation sequences. </p>
5875 <p>A given a canvas size of zero such as '<kbd>0x0</kbd>' forces it to
5876 recalculate the canvas size so the image (at its current offset) will appear
5877 completely on that canvas (unless it has a negative offset).</p>
5879 <p>Use <a href="command-line-options.html#repage">+repage</a> to completely remove/reset the virtual
5880 canvas meta-data from the images. </p>
5882 <p>The <a href="command-line-options.html#set">-set</a> '<kbd>page</kbd>' option can be used to
5883 directly assign virtual canvas meta-data. </p>
5886 <div style="margin: auto;">
5887 <h4><a id="resample"></a>-resample <em class="arg">horizontal</em>x<em class="arg">vertical</em></h4>
5890 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resample image to specified horizontal and vertical resolution.</td><td style='text-align:right;'></td></tr></table>
5892 <p>Resize the image so that its rendered size remains the same as the original
5893 at the specified target resolution. For example, if a 300 DPI image renders at
5894 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to
5895 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that
5896 only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of
5897 storing the image resolution. For formats which do not support an image
5898 resolution, the original resolution of the image must be specified via <a
5899 href="command-line-options.html#density">-density</a> on the command line prior to specifying the
5900 resample resolution.</p>
5902 <p>Note that Photoshop stores and obtains image resolution from a proprietary
5903 embedded profile. If this profile exists in the image, then Photoshop will
5904 continue to treat the image using its former resolution, ignoring the image
5905 resolution specified in the standard file header.</p>
5907 <div style="margin: auto;">
5908 <h4><a id="resize"></a>-resize <em class="arg">geometry</em></h4>
5911 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Resize an image.</td><td style='text-align:right;'></td></tr></table>
5913 <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
5914 ignored, and the <a href="command-line-options.html#gravity">-gravity</a> option has no effect.</p>
5916 <p>If the <a href="command-line-options.html#filter">-filter</a> option precedes the <a
5917 href="command-line-options.html#resize">-resize</a> option, the image is resized with the specified
5920 <p>Many image processing algorithms assume your image is in a linear-light
5921 coding. If your image is gamma-corrected, you can remove the nonlinear gamma
5922 correction, apply the transform, then restore it like this:</p>
5924 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \ <br/> -quality 92 passport.jpg</span></p>
5925 <div style="margin: auto;">
5926 <h4><a id="respect-parentheses"></a>-respect-parentheses</h4>
5929 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>settings remain in effect until parenthesis boundary.</td><td style='text-align:right;'></td></tr></table>
5931 <div style="margin: auto;">
5932 <h4><a id="reverse"></a>-reverse</h4>
5935 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Reverse the order of images in the current image list.</td><td style='text-align:right;'></td></tr></table>
5938 <div style="margin: auto;">
5939 <h4><a id="roll"></a>-roll {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4>
5942 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>roll an image vertically or horizontally by the amount given.</td><td style='text-align:right;'></td></tr></table>
5944 <p>A negative <em class="arg">x</em> offset rolls the image left-to-right.
5945 A negative <em class="arg">y</em> offset rolls the image top-to-bottom.</p>
5948 <div style="margin: auto;">
5949 <h4><a id="rotate"></a>-rotate <em class="arg">degrees</em>{<em class="arg"><</em>}{<em class="arg">></em>}</h4>
5952 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply Paeth image rotation (using shear operations) to the image.</td><td style='text-align:right;'></td></tr></table>
5954 <p>Use <kbd>></kbd> to rotate the image only if its width exceeds the
5955 height. <kbd><</kbd> rotates the image <em>only</em> if its width is less
5956 than the height. For example, if you specify <kbd>-rotate "-90>"</kbd> and
5957 the image size is 480x640, the image is not rotated. However, if the image is
5958 640x480, it is rotated by -90 degrees. If you use <kbd>></kbd> or
5959 <kbd><</kbd>, enclose it in quotation marks to prevent it from being
5960 misinterpreted as a file redirection.</p>
5962 <p>Empty triangles in the corners, left over from rotating the image, are
5963 filled with the <kbd>background</kbd> color. </p>
5965 <p>See also the <a href="command-line-options.html#distort">-distort</a> operator and specifically the
5966 '<kbd>ScaleRotateTranslate</kbd>' distort method. </p>
5969 <div style="margin: auto;">
5970 <h4><a id="sample"></a>-sample <em class="arg">geometry</em></h4>
5973 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify/magnify the image using pixel subsampling and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table>
5975 <p>Change the image size simply by directly sampling the pixels original
5976 image. When magnifying, pixels are replicated in blocks. When minifying,
5977 pixels are sub-sampled (i.e., some rows and columns are skipped over). </p>
5979 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
5980 a <a href="command-line-options.html#filter">-filter</a> setting of <kbd>point</kbd> (nearest
5981 neighbour), though <a href="command-line-options.html#sample">-sample</a> is a lot faster, as it
5982 avoids all the filter processing of the image. As such it completely ignores
5983 the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
5985 <p>The key feature of the <a href="command-line-options.html#sample">-sample</a> is that no new colors
5986 will be added to the resulting image, though some colors may disappear. </p>
5988 <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
5989 ignored, unlike <a href="command-line-options.html#resize">-resize</a>. </p>
5992 <div style="margin: auto;">
5993 <h4><a id="sampling-factor"></a>-sampling-factor <em class="arg">horizontal-factor</em>x<em class="arg">vertical-factor</em></h4>
5996 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.</td><td style='text-align:right;'></td></tr></table>
5998 <p>This option specifies the sampling factors to be used by the JPEG encoder
5999 for chroma downsampling. If this option is omitted, the JPEG library will use
6000 its own default values. When reading or writing the YUV format and when
6001 writing the M2V (MPEG-2) format, use <a
6002 href="command-line-options.html#sampling-factor">-sampling-factor 2x1</a> or <a
6003 href="command-line-options.html#sampling-factor">-sampling-factor 4:2:2</a> to specify the 4:2:2
6004 downsampling method.</p>
6006 <div style="margin: auto;">
6007 <h4><a id="scale"></a>-scale <em class="arg">geometry</em></h4>
6010 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>minify/magnify the image using pixel block averaging and pixel replication, respectively.</td><td style='text-align:right;'></td></tr></table>
6012 <p>Change the image size simply by replacing pixels by averaging pixels
6013 together when minifying, or replacing pixels when magnifying. </p>
6015 <p>The results are thus equivalent to using <a href="command-line-options.html#resize">-resize</a> with
6016 a <a href="command-line-options.html#filter">-filter</a> setting of <kbd>box</kbd>. Though it is a lot
6017 faster, as it avoids all the filter processing of the image. As such it
6018 completely ignores the current <a href="command-line-options.html#filter">-filter</a> setting. </p>
6020 <p>If when shrinking (minifying) images the original image is some integer
6021 multiple of the new image size, the number of pixels averaged together to
6022 produce the new pixel color is the same across the whole image. This is
6023 a special case known as 'binning' and is often used as a method of reducing
6024 noise in image such as those generated by digital cameras, especially in low
6025 light conditions. </p>
6028 <div style="margin: auto;">
6029 <h4><a id="scene"></a>-scene <em class="arg">value</em></h4>
6032 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set scene number.</td><td style='text-align:right;'></td></tr></table>
6034 <p>This option sets the scene number of an image or the first image in an image sequence.</p>
6036 <div style="margin: auto;">
6037 <h4><a id="screen"></a>-screen</h4>
6040 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the screen to capture.</td><td style='text-align:right;'></td></tr></table>
6042 <p>This option indicates that the GetImage request used to obtain the image
6043 should be done on the root window, rather than directly on the specified
6044 window. In this way, you can obtain pieces of other windows that overlap the
6045 specified window, and more importantly, you can capture menus or other popups
6046 that are independent windows but appear over the specified window.</p>
6048 <div style="margin: auto;">
6049 <h4><a id="seed"></a>-seed</h4>
6052 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>seed a new sequence of pseudo-random numbers</td><td style='text-align:right;'></td></tr></table>
6054 <div style="margin: auto;">
6055 <h4><a id="segment"></a>-segment <em class="arg">cluster-threshold</em>x<em class="arg">smoothing-threshold</em></h4>
6058 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>segment the colors of an image.</td><td style='text-align:right;'></td></tr></table>
6060 <p>Segment an image by analyzing the histograms of the color components and
6061 identifying units that are homogeneous with the fuzzy c-means technique. This
6062 is part of the ImageMagick color quantization routines. </p>
6064 <p>Specify <em class="arg">cluster threshold</em> as the number of pixels in
6065 each cluster that must exceed the cluster threshold to be considered valid.
6066 <em class="arg">Smoothing threshold</em> eliminates noise in the second
6067 derivative of the histogram. As the value is increased, you can expect
6068 a smoother second derivative. The default is 1.5.</p>
6070 <p>If the <a href="command-line-options.html#verbose">-verbose</a> setting is defined, a detailed report
6071 of the color clusters is returned.</p>
6074 <div style="margin: auto;">
6075 <h4><a id="selective-blur"></a>-selective-blur <em class="arg">radius</em><br />-selective-blur <em class="arg">radius</em>x<em class="arg">sigma</em>{<em class="arg">+threshold</em>}</h4>
6078 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Selectively blur pixels within a contrast threshold.</td><td style='text-align:right;'></td></tr></table>
6080 <p>Blurs those pixels that are less than or equal to the threshold in
6081 contrast. The threshold may be expressed as a fraction of <em
6082 class="QR">QuantumRange</em> or as a percentage.</p>
6084 <div style="margin: auto;">
6085 <h4><a id="separate"></a>-separate</h4>
6088 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>separate an image channel into a grayscale image. Specify the channel with <a href="command-line-options.html#channel">-channel</a>.</td><td style='text-align:right;'></td></tr></table>
6090 <div style="margin: auto;">
6091 <h4><a id="sepia-tone"></a>-sepia-tone <em class="arg">threshold</em></h4>
6094 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a sepia-toned photo.</td><td style='text-align:right;'></td></tr></table>
6096 <p>Specify <em class="arg">threshold</em> as the percent threshold of the intensity (0 - 99.9%).</p>
6098 <p>This option applies a special effect to the image, similar to the effect
6099 achieved in a photo darkroom by sepia toning. Threshold ranges from 0 to <em
6100 class="QR">QuantumRange</em> and is a measure of the extent of the sepia
6101 toning. A threshold of 80% is a good starting point for a reasonable
6106 <div style="margin: auto;">
6107 <h4><a id="set"></a>-set <em class="arg">key value</em></h4>
6108 <h4>+set <em class="arg">key</em></h4>
6111 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sets image attributes and properties for images in the current
6112 image sequence.</td><td style='text-align:right;'></td></tr></table>
6114 <p>This will assign (or modify) specific settings attached to all the images
6115 in the current image sequence. Using the <a href="command-line-options.html#set">+set</a> form of the
6116 option will either remove, or reset that setting to a default state, as
6119 <p>For example, it will modify specific well known image meta-data
6120 'attributes' such as those normally overridden by: the options <a
6121 href="command-line-options.html#delay" >-delay</a>, <a href="command-line-options.html#dispose" >-dispose</a>, and <a
6122 href="command-line-options.html#page" >-page</a>, <a href="command-line-options.html#colorspace" >-colorspace</a>; generally
6123 assigned before the image is read in, by using a <em class="arg">key</em> of
6126 <p>If the given <em class="arg">key</em> does not match a specific known
6127 'attribute ', such as shown above, the setting is stored as a a free form
6128 'property' string. Such settings are listed in <a href="command-line-options.html#verbose"
6129 >-verbose</a> information ("<kbd>info:</kbd>" output format) as "Properties".
6132 <p>This includes string 'properties' that are set by and assigned to images
6133 using the options <a href="command-line-options.html#comment" >-comment</a>, <a href="command-line-options.html#label"
6134 >-label</a>, <a href="command-line-options.html#caption" >-caption</a>. These options actually assign
6135 a global 'artifact' which are automatically assigned (and any <a href="escape.html" >Format Percent
6136 Escapes</a> expanded) to images as they are read in. For example:</p>
6138 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.png</span><span class='crtout'>identify -format %c rose.png</span><span class="crtprompt"> $ </span><span class='crtin'>Rose is a rose is a rose is a rose</span></p>
6139 <p>The set value can also make use of <a href="escape.html" >Format and Print Image
6140 Properties</a> in the defined value. For example:</p>
6142 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set origsize '%wx%h' -resize 50% \</span><span class='crtout'> -format 'Old size = %[origsize] New size = %wx%h' info:</span><span class="crtprompt"> $ </span><span class='crtin'>Old size = 70x46 New size = 35x23</span></p>
6143 <p>Other well known 'properties' that are availible include:
6144 '<kbd>date:create</kbd>' and '<kbd>date:modify</kbd>' and
6145 '<kbd>signature</kbd>'. </p>
6147 <p>The <a href="command-line-options.html#repage">-repage</a> operator will also allow you to modify
6148 the '<kbd>page</kbd>' attribute of an image for images already in memory (also
6149 see <a href="command-line-options.html#repage">-page</a>). However it is designed to provide a finer
6150 control of the sub-parts of this 'attribute'. The <a href="command-line-options.html#set">-set page</a>
6151 option will only provide a direct, unmodified assignment of '<kbd>page</kbd>'
6154 <p>This option can also associate a colorspace or profile with your image.
6157 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd</span></p>
6158 <p>Some 'properties' must be defined in a specific way to be used. For
6159 example only 'properties' prefixed with "<kbd>filename:</kbd>" can be used to
6160 modify the output filename of an image. For example</p>
6162 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'</span></p>
6163 <p>If the setting value is prefixed with "<kbd>option:</kbd>" the setting will
6164 be saved as a global "Artifact" exactly as if it was set using the <a
6165 href="command-line-options.html#define" >-define</a> option. As such settings are global in scope, they
6166 can be used to pass 'attributes' and 'properties' of one specific image,
6167 in a way that allows you to use them in a completely different image, even if
6168 the original image has long since been modified or destroyed. For example: </p>
6170 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose: -set option:rosesize '%wx%h' -delete 0 \</span><span class='crtout'> label:'%[rosesize]' label_size_of_rose.gif</span></p>
6171 <p>Note that <a href="escape.html" >Format Percent Escapes</a> will only match
6172 a 'artifact' if the given <em class="arg">key</em> does not match an existing
6173 'attribute' or 'property'. </p>
6175 <p>You can set the attributes of the image registry by prefixing the value
6176 with <kbd>registry:</kbd>.</p>
6178 <p>The <a href="command-line-options.html#set">-set profile</a> option can also be used to inject
6179 previously-formatted ancillary chunks into the output PNG file, using
6180 the commandline option as shown below or by setting the profile via a
6181 programming interface:</p>
6183 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -set profile PNG-chunk-x:<filename> out.png</span></p>
6184 <p>where <em>x</em> is a location flag and
6185 <em class="arg">filename</em> is a file containing the chunk
6186 name in the first 4 bytes, then a colon (":"), followed by the chunk data.
6187 This encoder will compute the chunk length and CRC, so those must not
6188 be included in the file.</p>
6190 <p>"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),
6191 or "e" (end, i.e., after IDAT). If you want to write multiple chunks
6192 of the same type, then add a short unique string after the "x" to prevent
6193 subsequent profiles from overwriting the preceding ones, e.g.,</p>
6196 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -set profile PNG-chunk-b01:file01 / <br/>
6197 -profile PNG-chunk-b02:file02 out.png</span></p>
6201 <div style="margin: auto;">
6202 <h4><a id="shade"></a>-shade <em class="arg">azimuth</em>x<em class="arg">elevation</em></h4>
6205 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>shade the image using a distant light source.</td><td style='text-align:right;'></td></tr></table>
6207 <p>Specify <em class="arg">azimuth</em> and <em class="arg">elevation</em> as
6208 the position of the light source. Use <a href="command-line-options.html#shade">+shade</a> to return
6209 the shading results as a grayscale image.</p>
6211 <div style="margin: auto;">
6212 <h4><a id="shadow"></a>-shadow <em class="arg">percent-opacity</em>{x<em class="arg">sigma</em>}{<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em>{<em class="arg">%</em>}</h4>
6215 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate an image shadow.</td><td style='text-align:right;'></td></tr></table>
6217 <div style="margin: auto;">
6219 id="shared-memory"></a>-shared-memory</h4>
6222 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>use shared memory.</td><td style='text-align:right;'></td></tr></table>
6224 <p>This option specifies whether the utility should attempt to use shared
6225 memory for pixmaps. ImageMagick must be compiled with shared memory support,
6226 and the display must support the <em class="arg">MIT-SHM</em> extension.
6227 Otherwise, this option is ignored. The default is <kbd>True</kbd>.</p>
6229 <div style="margin: auto;">
6230 <h4><a id="sharpen"></a>-sharpen <em class="arg">radius</em><br />-sharpen <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">bias</em></h4>
6233 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sharpen the image.</td><td style='text-align:right;'></td></tr></table>
6235 <p>Use a Gaussian operator of the given radius and standard deviation (sigma).</p>
6237 <div style="margin: auto;">
6238 <h4><a id="shave"></a>-shave <em class="arg">geometry</em></h4>
6241 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shave pixels from the image edges.</td><td style='text-align:right;'></td></tr></table>
6243 <p>The <em class="arg">size</em> portion of the <em class="arg">geometry</em>
6244 argument specifies the width of the region to be removed from both sides of
6245 the image and the height of the regions to be removed from top and bottom.
6246 Offsets are ignored.</p>
6248 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6250 <div style="margin: auto;">
6251 <h4><a id="shear"></a>-shear <em class="arg">Xdegrees</em>[x<em class="arg">Ydegrees</em>]</h4>
6254 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shear the image along the x-axis and/or y-axis.</td><td style='text-align:right;'></td></tr></table>
6256 <p>The shear angles may be positive, negative, or zero. When <em
6257 class="arg">Ydegrees</em> is omitted it defaults to 0. When both angles are
6258 given, the horizontal component of the shear is performed before the vertical
6261 <p>Shearing slides one edge of an image along the x-axis or y-axis (i.e.,
6262 horizontally or vertically, respectively),creating a parallelogram. The amount
6263 of each is controlled by the respective shear angle. For horizontal shears,
6264 <em class="arg">Xdegrees</em> is measured clockwise relative to "up" (the
6265 negative y-axis), sliding the top edge to the right when 0°<<em
6266 class="arg">Xdegrees</em><90° and to the left when 90°<<em
6267 class="arg">Xdegrees</em><180°. For vertical shears <em
6268 class="arg">Ydegrees</em> is measured clockwise relative to "right" (the
6269 positive x-axis), sliding the right edge down when 0°<<em
6270 class="arg">Ydegrees</em><90° and up when 90°<<em
6271 class="arg">Ydegrees</em><180°.</p>
6273 <p>Empty triangles left over from shearing the image are filled with the color
6274 defined by the <a href="command-line-options.html#fill">-background</a> option. The color is specified
6275 using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6277 <p>The horizontal shear is performed before the vertical part. This is
6278 important to note, since horizontal and vertical shears do not
6279 <em>commute</em>, i.e., the order matters in a sequence of shears. For
6280 example, the following two commands are not equivalent.</p>
6282 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -shear 20x0 -shear 0x60 logo-sheared.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -shear 0x60 -shear 20x0 logo-sheared.png</span></p>
6283 <p>The first of the two commands above is equivalent to the following, except
6284 for the amount of empty space created; the command that follows generates
6285 a smaller image, and so is a better choice in terms of time and space.</p>
6287 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert logo: -shear 20x60 logo-sheared.png</span></p>
6288 <div style="margin: auto;">
6289 <h4><a id="sigmoidal-contrast"></a>-sigmoidal-contrast <em class="arg">contrast</em>x<em class="arg">mid-point</em></h4>
6292 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>increase the contrast without saturating highlights or shadows.</td><td style='text-align:right;'></td></tr></table>
6294 <p>Increase the contrast of the image using a sigmoidal transfer function
6295 without saturating highlights or shadows. <em class="arg">Contrast</em>
6296 indicates how much to increase the contrast. For example, near 0 is none, 3 is
6297 typical and 20 is a lot. Note that exactly zero is invalid, but 0.0001 is
6298 negligibly different from no change in contrast. <em
6299 class="arg">mid-point</em> indicates where midtones fall in the resultant
6300 image (0 is white; 50% is middle-gray; 100% is black). By default the image
6301 contrast is increased, use <em class="arg">+sigmoidal-contrast</em> to
6302 decrease the contrast.</p>
6304 <p>To achieve the equivalent of a sigmoidal brightness change, use <em
6305 class="arg">-sigmoidal-contrast brightnessx0%</em> to increase brightness and
6306 class="arg">+sigmoidal-contrast brightnessx0%</em> to decrease brightness.</p>
6308 <div style="margin: auto;">
6309 <h4><a id="silent"></a>-silent</h4>
6312 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>operate silently.</td><td style='text-align:right;'></td></tr></table>
6314 <div style="margin: auto;">
6315 <h4><a id="size"></a>-size <em class="arg">width</em>[x<em class="arg">height</em>][<em class="arg">+offset</em>]</h4>
6318 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the width and height of the image.</td><td style='text-align:right;'></td></tr></table>
6320 <p>Use this option to specify the width and height of raw images whose
6321 dimensions are unknown such as <kbd>GRAY</kbd>, <kbd>RGB</kbd>, or
6322 <kbd>CMYK</kbd>. In addition to width and height, use <a
6323 href="command-line-options.html#size">-size</a> with an offset to skip any header information in the
6324 image or tell the number of colors in a <kbd>MAP</kbd> image file, (e.g. -size
6327 <p>For Photo CD images, choose from these sizes:</p>
6337 <div style="margin: auto;">
6338 <h4><a id="sketch"></a>-sketch <em class="arg">radius</em><br />-sketch <em class="arg">radius</em>x<em class="arg">sigma</em>+<em class="arg">angle</em></h4>
6341 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>simulate a pencil sketch.</td><td style='text-align:right;'></td></tr></table>
6343 <p>Sketch with the given radius, standard deviation (sigma), and angle. The
6344 angle given is the angle toward which the image is sketched. That is the
6345 direction people would consider the object is coming from. </p>
6347 <div style="margin: auto;">
6348 <h4><a id="smush"></a>-smush <em class="arg">offset</em></h4>
6351 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>smush an image sequence together.</td><td style='text-align:right;'></td></tr></table>
6353 <div style="margin: auto;">
6354 <h4><a id="snaps"></a>-snaps <em class="arg">value</em></h4>
6357 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the number of screen snapshots.</td><td style='text-align:right;'>[<a href="import.html">import</a>]</td></tr></table>
6359 <p>Use this option to grab more than one image from the X server screen, to create an animation sequence.</p>
6361 <div style="margin: auto;">
6362 <h4><a id="solarize"></a>-solarize <em class="arg">threshold</em></h4>
6365 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>negate all pixels above the threshold level.</td><td style='text-align:right;'></td></tr></table>
6367 <p>Specify <em class="arg">factor</em> as the percent threshold of the intensity (0 - 99.9%).</p>
6369 <p>This option produces a <em class="arg">solarization</em> effect seen when
6370 exposing a photographic film to light during the development process.</p>
6372 <div style="margin: auto;">
6373 <h4><a id="sparse-color"></a>-sparse-color <em
6374 class="arg">method</em> '<em class="arg">x</em>,<em class="arg">y</em> <em class="arg">color</em> ...'</h4>
6377 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'> color the given image using the specified points of color, and filling the other intervening colors using the given methods. </td><td style='text-align:right;'></td></tr></table>
6383 <th align="left" style="width: 8%">Method</th>
6384 <th align="left">Description</th>
6388 <td valign="top">barycentric</td>
6389 <td valign="top">three point triangle of color given 3 points.
6390 Giving only 2 points will form a linear gradient between those points.
6391 The gradient generated extends beyond the triangle created by those
6396 <td valign="top">bilinear</td>
6397 <td valign="top">Like barycentric but for 4 points. Less than 4 points
6398 fall back to barycentric. </td>
6401 <td valign="top">voronoi</td>
6402 <td valign="top">Simply map each pixel to the to nearest color point
6403 given. The result are polygonal 'cells' of solid color. </td>
6407 <td valign="top">shepards</td>
6408 <td valign="top">Colors points biased on the ratio of inverse distance
6409 squared. Generating spots of color in a sea of the average of
6414 <td valign="top">inverse</td>
6415 <td valign="top">Colors points biased on the ratio of inverse distance.
6416 This generates sharper points of color rather than rounded spots of
6417 '<kbd>shepards</kbd>' Generating spots of color in a sea of the
6418 average of colors. </td>
6424 <p>The points are placed according to the images location on the virtual
6425 canvas (<a href="command-line-options.html#page" >-page</a> or <a href="command-line-options.html#repage" >-repage</a>
6426 offset), and do not actually have to exist on the given image, but may be
6427 some point beyond the edge of the image. All points are floating point values.
6430 <p>Only the color channels defined by the <a href="command-line-options.html#channel" >-channel</a> are
6431 modified, which means that by default matte/alpha transparency channel is not
6432 effected. Typically transparency channel is turned off either before or after
6435 Of course if some color points are transparent to generate a transparent
6436 gradient, then the image also requires transparency enabled to store the
6439 <p>All the above methods when given a single point of color will replace all
6440 the colors in the image with the color given, regardless of the point. This is
6441 logical, and provides an alternative technique to recolor a image to some
6445 <div style="margin: auto;">
6446 <h4><a id="splice"></a>-splice <em class="arg">geometry</em></h4>
6449 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Splice the current background color into the image.</td><td style='text-align:right;'></td></tr></table>
6451 <p>This will add rows and columns of the current <a
6452 href="command-line-options.html#background">-background</a> color into the given image according to the
6453 given <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
6454 image into four quadrants, separating them by the inserted rows and columns.
6457 If a dimension of geometry is zero no rows or columns will be added for that
6458 dimension. Similarly using a zero offset with the appropriate <a
6459 href="command-line-options.html#gravity">-gravity</a> setting will add rows and columns to the edges of
6460 the image, padding the image only along that one edge. Edge padding is what <a
6461 href="command-line-options.html#splice">-splice</a> is most commonly used for. </p>
6463 <p>If the exact same <em class="arg">geometry</em> and <a
6464 href="command-line-options.html#gravity">-gravity</a> is later used with <a href="command-line-options.html#chop">-chop</a> the
6465 added added all splices removed. </p>
6467 <div style="margin: auto;">
6468 <h4><a id="spread"></a>-spread <em class="arg">amount</em></h4>
6471 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>displace image pixels by a random amount.</td><td style='text-align:right;'></td></tr></table>
6473 <p>The argument <em class="arg">amount</em> defines the size of the
6474 neighborhood around each pixel from which to choose a candidate pixel to
6477 <div style="margin: auto;">
6478 <h4><a id="statistic"></a>-statistic <em class="arg">type</em> <em class="arg">geometry</em></h4>
6481 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>replace each pixel with corresponding statistic from the neighborhood.</td><td style='text-align:right;'>[<a href="convert.html">convert</a>, <a href="mogrify.html">mogrify</a>]</td></tr></table>
6483 <p>Choose from these statistic types:</p>
6485 Gradient maximum difference in area
6486 Maximum maximum value per channel in neighborhood
6487 Minimum minimum value per channel in neighborhood
6488 Mean average value per channel in neighborhood
6489 Median median value per channel in neighborhood
6490 Mode mode (most frequent) value per channel in neighborhood
6491 Nonpeak value just before or after the median value per channel in neighborhood
6494 <div style="margin: auto;">
6495 <h4><a id="stegano"></a>-stegano <em class="arg">offset</em></h4>
6498 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>hide watermark within an image.</td><td style='text-align:right;'></td></tr></table>
6500 <p>Use an offset to start the image hiding some number of pixels from the
6501 beginning of the image. Note this offset and the image size. You will need
6502 this information to recover the steganographic image (e.g. display -size
6503 320x256+35 stegano:image.png).</p>
6505 <div style="margin: auto;">
6506 <h4><a id="stereo"></a>-stereo <em class="arg">+x</em>{<em class="arg">+y</em>}</h4>
6509 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>composite two images to create a stereo anaglyph.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
6511 <p>The left side of the stereo pair is saved as the red channel of the output
6512 image. The right side is saved as the green channel. Red-green stereo glasses
6513 are required to properly view the stereo image.</p>
6515 <div style="margin: auto;">
6516 <h4><a id="storage-type"></a>-storage-type <em class="arg">type</em></h4>
6519 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>pixel storage type. Here are the valid types:</td><td style='text-align:right;'></td></tr></table>
6522 char unsigned characters
6527 quantum pixels in the native depth of your ImageMagick distribution
6528 short unsigned shorts
6531 <p>Float and double types are normalized from 0.0 to 1.0 otherwise the pixels
6532 values range from 0 to the maximum value the storage type can support.</p>
6534 <div style="margin: auto;">
6535 <h4><a id="stretch"></a>-stretch <em class="arg">fontStretch</em></h4>
6538 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a type of stretch style for fonts.</td><td style='text-align:right;'></td></tr></table>
6540 <p>This setting suggests a type of stretch that ImageMagick should try to
6541 apply to the currently selected font family. Select <em
6542 class="arg">fontStretch</em> from the following.</p>
6557 <p>To print a complete list of stretch types, use <a href="command-line-options.html#list">-list
6560 <p>For other settings that affect fonts, see the options <a
6561 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
6562 href="command-line-options.html#style">-style</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
6564 <div style="margin: auto;">
6565 <h4><a id="strip"></a>-strip</h4>
6568 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>strip the image of any profiles or comments.</td><td style='text-align:right;'></td></tr></table>
6570 <div style="margin: auto;">
6571 <h4><a id="stroke"></a>-stroke <em class="arg">color</em></h4>
6574 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>color to use when stroking a graphic primitive.</td><td style='text-align:right;'></td></tr></table>
6576 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6578 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
6580 <div style="margin: auto;">
6581 <h4><a id="strokewidth"></a>-strokewidth <em class="arg">value</em></h4>
6584 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the stroke width.</td><td style='text-align:right;'></td></tr></table>
6586 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
6588 <div style="margin: auto;">
6589 <h4><a id="style"></a>-style <em class="arg">fontStyle</em></h4>
6592 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font style for text.</td><td style='text-align:right;'></td></tr></table>
6594 <p>This setting suggests a font style that ImageMagick should try to apply to
6595 the currently selected font family. Select <em class="arg">fontStyle</em> from
6605 <p>For other settings that affect fonts, see the options <a
6606 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
6607 href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#weight">-weight</a>. </p>
6609 <div style="margin: auto;">
6610 <h4><a id="subimage-search"></a>-subimage-search</h4>
6613 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>search for subimage.</td><td style='text-align:right;'>[<a href="compare.html">compare</a>]</td></tr></table>
6615 <p>This option is required to have compare search for the best match location
6616 of a small image within a larger image. This search will produce two images
6617 (or two frames). The first is the "difference" image and the second will
6618 be the "match score" image.</p>
6620 <p>The "match-score" image is smaller containing a pixel for ever possible
6621 position of the top-left corner of the given sub-image. that is its size will
6622 be the size of the larger_image - sub_image + 1. The brightest location in
6623 this image is the location s the locate on the best match that is also
6624 reported. Note that this may or may nor be a perfect match, and the actual
6625 brightness will reflect this. Other bright 'peaks' can be used to locate other
6626 possible matching locations. </p>
6628 <p>Note that the search will try to compare the sub-image at every possible
6629 location in the larger image, as such it can be very slow. The smaller the
6630 sub-image the faster this search is. </p>
6633 <div style="margin: auto;">
6634 <h4><a id="swap"></a>-swap <em class="arg">index,index</em></h4>
6637 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Swap the positions of two images in the image sequence.</td><td style='text-align:right;'></td></tr></table>
6639 <p>For example, <a href="command-line-options.html#swap">-swap 0,2</a> swaps the first and the third
6640 images in the current image sequence. Use <a href="command-line-options.html#swap">+swap</a> to switch
6641 the last two images in the sequence.</p>
6643 <div style="margin: auto;">
6644 <h4><a id="swirl"></a>-swirl <em class="arg">degrees</em></h4>
6647 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>swirl image pixels about the center.</td><td style='text-align:right;'></td></tr></table>
6649 <p><em class="arg">Degrees</em> defines the tightness of the swirl.</p>
6651 <div style="margin: auto;">
6652 <h4><a id="synchronize"></a>-synchronize</h4>
6655 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>synchronize image to storage device.</td><td style='text-align:right;'></td></tr></table>
6657 <div style="margin: auto;">
6658 <h4><a id="taint"></a>-taint</h4>
6661 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mark the image as modified.</td><td style='text-align:right;'></td></tr></table>
6663 <div style="margin: auto;">
6664 <h4><a id="text-font"></a>-text-font <em class="arg">name</em></h4>
6667 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>font for writing fixed-width text.</td><td style='text-align:right;'></td></tr></table>
6669 <p>Specifies the name of the preferred font to use in fixed (typewriter style)
6670 formatted text. The default is 14 point <em class="arg">Courier</em>.</p>
6672 <p>You can tag a font to specify whether it is a PostScript, TrueType, or
6673 OPTION1 font. For example, <kbd>Courier.ttf</kbd> is a TrueType font and
6674 <kbd>x:fixed</kbd> is OPTION1.</p>
6676 <div style="margin: auto;">
6677 <h4><a id="texture"></a>-texture <em class="arg">filename</em></h4>
6680 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>name of texture to tile onto the image background.</td><td style='text-align:right;'></td></tr></table>
6682 <div style="margin: auto;">
6683 <h4><a id="threshold"></a>-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
6686 <!-- {<em class="arg">green,blue,opacity</em>}
6687 <p>If the green or blue value is omitted, these channels use the same value as
6688 the first one provided. If all three color values are the same, the result is
6689 a bi-level image. If the opacity threshold is omitted, OpaqueOpacity is used
6690 and any partially transparent pixel becomes fully transparent.</p>
6693 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Apply simultaneous black/white threshold to the image.</td><td style='text-align:right;'></td></tr></table>
6695 <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
6696 maximum channel value, while all other values are assigned the minimum.</p>
6698 <p> The threshold value can be given as a percentage or as an absolute integer
6699 value corresponding to the desired channel value. When given as an integer,
6700 the minimum attainable value is 0 (corresponding to black when all channels
6701 are affected), but the maximum value (corresponding to white) is that of the
6702 <kbd>quantum depth</kbd> of the particular build of ImageMagick, and is
6703 therefore dependent on the installation. For that reason, a reasonable
6704 recommendation for most applications is to specify the threshold values as
6707 <p> The following would force pixels with red values above 50% to have 100%
6708 red values, while those at or below 50% red would be set to 0 in the red
6709 channel. The green, blue, and alpha channels (if present) would be unchanged.
6712 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -channel red -threshold 50% out.png</span></p>
6713 <p>As (possibly) impractical but instructive examples, the following would
6714 generate an all-black and an all-white image with the same dimensions as the
6718 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -threshold 100% black.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>convert in.png -threshold -1 white.png</span></p>
6719 <p>Note that the values of the transparency channel is treated as 'matte'
6720 values (0 is opaque) and not as 'alpha' values (0 is transparent).</p>
6722 <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>.
6725 <div style="margin: auto;">
6726 <h4><a id="thumbnail"></a>-thumbnail <em class="arg">geometry</em></h4>
6729 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Create a thumbnail of the image.</td><td style='text-align:right;'></td></tr></table>
6731 <p>This is similar to <a href="command-line-options.html#resize">-resize</a>, except it is optimized
6732 for speed and any image profile, other than a color profile, is removed to
6733 reduce the thumbnail size. To strip the color profiles as well, add <a
6734 href="command-line-options.html#strip">-strip</a> just before of after this option.</p>
6736 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6738 <div style="margin: auto;">
6739 <h4><a id="tile"></a>-tile <em class="arg">filename</em></h4>
6742 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the tile image used for filling a subsequent graphic primitive.</td><td style='text-align:right;'></td></tr></table>
6744 <div style="margin: auto;">
6745 <h4>-tile <em class="arg">geometry</em></h4>
6748 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the layout of images .</td><td style='text-align:right;'>[<a href="montage.html">montage</a>]</td></tr></table>
6750 <p>See <a href="command-line-processing.html#geometry">Image Geometry</a> for complete details about the <em class="arg">geometry</em> argument.</p>
6752 <div style="margin: auto;">
6756 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specifies that a subsequent composite operation is repeated across and down image.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
6758 <div style="margin: auto;">
6759 <h4><a id="tile-offset"></a>-tile-offset {<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em></h4>
6762 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify the offset for tile images, relative to the background image it is tiled on.</td><td style='text-align:right;'></td></tr></table>
6764 <p>This should be set before the tiling image is set by <a href="command-line-options.html#tile"
6765 >-tile</a> or <a href="command-line-options.html#texture" >-texture</a>, or directly applied for
6766 creating a tiled canvas using <kbd>TILE:</kbd> or <kbd>PATTERN:</kbd> input
6769 <p>Internally ImageMagick does a <a href="command-line-options.html#roll" >-roll</a> of the tile image
6770 by the arguments given when the tile image is set. </p>
6772 <div style="margin: auto;">
6773 <h4><a id="tint"></a>-tint <em class="arg">value</em></h4>
6776 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Tint the image with the fill color.</td><td style='text-align:right;'></td></tr></table>
6778 <p>Tint the image with the fill color.</p>
6780 <p>Specify the amount of tinting as a percentage. Pure colors like black,
6781 white red, yellow, will not be affected by -tint. Only mid-range colors such
6782 as the various shades of grey.</p>
6784 <div style="margin: auto;">
6785 <h4><a id="title"></a>-title <em class="arg">string</em></h4>
6788 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Assign a title to displayed image.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>, <a href="montage.html">montage</a>]</td></tr></table>
6790 <p>Use this option to assign a specific title to the image. This assigned to
6791 the image window and is typically displayed in the window title bar.
6792 Optionally you can include the image filename, type, width, height, Exif data,
6793 or other image attribute by embedding special format characters described
6794 under the <a href="command-line-options.html#format">-format</a> option.</p>
6799 -title "%m:%f %wx%h"
6802 <p>produces an image title of <kbd>MIFF:bird.miff 512x480</kbd> for an image
6803 titled <kbd>bird.miff</kbd> and whose width is 512 and height is 480.</p>
6806 <div style="margin: auto;">
6807 <h4><a id="transform"></a>-transform</h4>
6810 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>transform the image.</td><td style='text-align:right;'></td></tr></table>
6812 <p>This option applies the transformation matrix from a previous <a href="command-line-options.html#affine">-affine</a> option.</p>
6814 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg</span></p>
6816 <p>This operator has been now been superseded by the <a
6817 href="command-line-options.html#distort">-distort</a> '<kbd>AffineProjection</kbd>' method. </p>
6820 <div style="margin: auto;">
6821 <h4><a id="transparent"></a>-transparent <em class="arg">color</em></h4>
6824 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make this color transparent within the image.</td><td style='text-align:right;'></td></tr></table>
6826 <p>The <em class="arg">color</em> argument is defined using the format
6827 described under the <a href="command-line-options.html#fill">-fill</a> option. The <a href="command-line-options.html#fuzz"
6828 >-fuzz</a> setting can be used to match and replace colors similar to the one
6831 <p>Use <a href="command-line-options.html#transparent" >+transparent</a> to invert the pixels matched.
6832 that is make all non-matching colors transparent. </p>
6834 <p>The <a href="command-line-options.html#opaque">-opaque</a> operator is exactly the same as <a
6835 href="command-line-options.html#transparent" >-transparent</a> but replaces the matching color with the
6836 current <a href="command-line-options.html#fill">-fill</a> color setting, rather than transparent.
6837 However the <a href="command-line-options.html#transparent" >-transparent</a> operator also ensures
6838 that the image has an alpha channel enabled, as per "<kbd><a href="command-line-options.html#alpha"
6839 >-alpha</a> set</kbd>", and does not require you to modify the <a
6840 href="command-line-options.html#channel">-channel</a> to enable alpha channel handling. </p>
6842 <p>Note that this does not define the color as being the 'transparency color'
6843 used for color-mapped image formats, such as GIF. For that use <a
6844 href="command-line-options.html#transparent-color" >-transparent-color</a> </p>
6847 <div style="margin: auto;">
6848 <h4><a id="transparent-color"></a>-transparent-color <em class="arg">color</em></h4>
6851 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set the transparent color.</td><td style='text-align:right;'></td></tr></table>
6853 <p>Sometimes this is used for saving to image formats such as
6854 GIF and PNG8 which uses this color to represent boolean transparency. This
6855 does not make a color transparent, it only defines what color the transparent
6856 color is in the color palette of the saved image. Use <a
6857 href="command-line-options.html#transparent">-transparent</a> to make an opaque color transparent.</p>
6859 <p>This option allows you to have both an opaque visible color, as well as a
6860 transparent color of the same color value without conflict. That is, you can
6861 use the same color for both the transparent and opaque color areas within an
6862 image. This, in turn, frees to you to select a transparent color that is
6863 appropriate when an image is displayed by an application that does not handle a
6864 transparent color index, while allowing ImageMagick to correctly handle images of this
6867 <p>The default transparent color is <kbd>#00000000</kbd>, which is fully transparent black.</p>
6869 <div style="margin: auto;">
6870 <h4><a id="transpose"></a>-transpose</h4>
6873 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mirror the image along the top-left to bottom-right diagonal.</td><td style='text-align:right;'></td></tr></table>
6875 <p> This option mathematically transposes the pixel array. It is equivalent to the sequence <kbd>-flip -rotate 90</kbd>.
6878 <div style="margin: auto;">
6879 <h4><a id="transverse"></a>-transverse</h4>
6882 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Mirror the image along the images bottom-left top-right diagonal. Equivalent to the operations <kbd>-flop -rotate 90</kbd>.</td><td style='text-align:right;'></td></tr></table>
6885 <div style="margin: auto;">
6886 <h4><a id="treedepth"></a>-treedepth <em class="arg">value</em></h4>
6889 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>tree depth for the color reduction algorithm.</td><td style='text-align:right;'></td></tr></table>
6891 <p>Normally, this integer value is zero or one. A value of zero or one causes
6892 the use of an optimal tree depth for the color reduction algorithm.</p>
6894 <p>An optimal depth generally allows the best representation of the source
6895 image with the fastest computational speed and the least amount of memory.
6896 However, the default depth is inappropriate for some images. To assure the
6897 best representation, try values between 2 and 8 for this parameter. Refer to
6898 the <a href="quantize.html"
6899 >color reduction algorithm</a> for more details.</p>
6901 <p>The <a href="command-line-options.html#colors">-colors</a> or <a href="command-line-options.html#monochrome">-monochrome</a>
6902 option, or writing to an image format which requires color reduction, is
6903 required for this option to take effect.</p>
6905 <div style="margin: auto;">
6906 <h4><a id="trim"></a>-trim</h4>
6909 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>trim an image.</td><td style='text-align:right;'></td></tr></table>
6911 <p>This option removes any edges that are exactly the same color as the corner
6912 pixels. Use <a href="command-line-options.html#fuzz">-fuzz</a> to make <a href="command-line-options.html#trim">-trim</a> remove
6913 edges that are nearly the same color as the corner pixels.</p>
6915 <p>The page or virtual canvas information of the image is preserved allowing
6916 you to extract the result of the <a href="command-line-options.html#trim">-trim</a> operation from the
6917 image. Use a <a href="command-line-options.html#repage">+repage</a> to remove the virtual canvas page
6918 information if it is unwanted.</p>
6920 <p>If the trimmed image 'disappears' an warning is produced, and a special
6921 single pixel transparent 'missed' image is returned, in the same way as when a
6922 <a href="command-line-options.html#crop">-crop</a> operation 'misses' the image proper. </p>
6925 <div style="margin: auto;">
6926 <h4><a id="type"></a>-type <em class="arg">type</em></h4>
6929 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the image type.</td><td style='text-align:right;'></td></tr></table>
6930 <p>Choose from: <kbd>Bilevel</kbd>,
6931 <kbd>Grayscale</kbd>, <kbd>GrayscaleMatte</kbd>, <kbd>Palette</kbd>,
6932 <kbd>PaletteMatte</kbd>, <kbd>TrueColor</kbd>, <kbd>TrueColorMatte</kbd>,
6933 <kbd>ColorSeparation</kbd>, or <kbd>ColorSeparationMatte</kbd>.</p>
6935 <p>Normally, when a format supports different subformats such as grayscale and
6936 truecolor, the encoder will try to choose an efficient subformat. The <a
6937 href="command-line-options.html#type">-type</a> option can be used to override this behavior. For
6938 example, to prevent a JPEG from being written in grayscale format even though
6939 only gray pixels are present, use.</p>
6941 <p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert bird.png -type TrueColor bird.jpg</span></p>
6942 <p>Similarly, use <a href="command-line-options.html#type">-type TrueColorMatte</a> to force the
6943 encoder to write an alpha channel even though the image is opaque, if the
6944 output format supports transparency.</p>
6946 <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>
6948 <div style="margin: auto;">
6949 <h4><a id="undercolor"></a>-undercolor <em class="arg">color</em></h4>
6952 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>set the color of the annotation bounding box.</td><td style='text-align:right;'></td></tr></table>
6954 <p>The color is specified using the format described under the <a href="command-line-options.html#fill">-fill</a> option.</p>
6956 <p>See <a href="command-line-options.html#draw">-draw</a> for further details.</p>
6959 <div style="margin: auto;">
6960 <h4><a id="update"></a>-update <em class="arg">seconds</em></h4>
6963 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>detect when image file is modified and redisplay.</td><td style='text-align:right;'></td></tr></table>
6965 <p>Suppose that while you are displaying an image the file that is currently
6966 displayed is over-written. <kbd>display</kbd> will automagically detect that
6967 the input file has been changed and update the displayed image
6971 <div style="margin: auto;">
6972 <h4><a id="unique-colors"></a>-unique-colors</h4>
6975 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>discard all but one of any pixel color.</td><td style='text-align:right;'></td></tr></table>
6978 <div style="margin: auto;">
6979 <h4><a id="units"></a>-units <em class="arg">type</em></h4>
6982 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>the units of image resolution.</td><td style='text-align:right;'></td></tr></table>
6984 <p>Choose from: <kbd>Undefined</kbd>, <kbd>PixelsPerInch</kbd>, or
6985 <kbd>PixelsPerCentimeter</kbd>. This option is normally used in conjunction
6986 with the <a href="command-line-options.html#density">-density</a> option.</p>
6989 <div style="margin: auto;">
6990 <h4><a id="unsharp"></a>-unsharp <em class="arg">radius</em><br />-unsharp <em class="arg">radius</em>x<em class="arg">sigma</em>{<em class="arg">+amount</em>}{<em class="arg">+threshold</em>}</h4>
6993 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>sharpen the image with an unsharp mask operator.</td><td style='text-align:right;'></td></tr></table>
6995 <p>The <a href="command-line-options.html#unsharp">-unsharp</a> option sharpens an image. The image is
6996 convolved with a Gaussian operator of the given radius and standard deviation
6997 (sigma). For reasonable results, radius should be larger than sigma. Use
6998 a radius of 0 to have the method select a suitable radius.</p>
7000 <p>The parameters are:</p>
7003 radius The radius of the Gaussian, in pixels, not counting the center
7005 sigma The standard deviation of the Gaussian, in pixels (default 1.0).
7006 amount The fraction of the difference between the original and the blur
7007 image that is added back into the original (default 1.0).
7008 threshold The threshold, as a fraction of <em class="QR">QuantumRange</em>, needed to apply the
7009 difference amount (default 0.05).
7013 <div style="margin: auto;">
7014 <h4><a id="verbose"></a>-verbose</h4>
7017 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print detailed information about the image when this option
7018 precedes the <a href="command-line-options.html#identify">-identify</a> option or
7019 <kbd>info:</kbd>.</td><td style='text-align:right;'></td></tr></table>
7022 <div style="margin: auto;">
7023 <h4><a id="version"></a>-version</h4>
7026 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>print ImageMagick version string and exit.</td><td style='text-align:right;'></td></tr></table>
7029 <div style="margin: auto;">
7030 <h4><a id="view"></a>-view <em class="arg">string</em></h4>
7033 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>FlashPix viewing parameters.</td><td style='text-align:right;'></td></tr></table>
7036 <div style="margin: auto;">
7037 <h4><a id="vignette"></a>-vignette <em class="arg">radius</em>{x<em class="arg">sigma</em>}{<em class="arg">+-</em>}<em class="arg">x</em>{<em class="arg">+-</em>}<em class="arg">y</em>{<em class="arg">%</em>}</h4>
7040 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>soften the edges of the image in vignette style.</td><td style='text-align:right;'></td></tr></table>
7043 <div style="margin: auto;">
7044 <h4><a id="virtual-pixel"></a>-virtual-pixel <em class="arg">method</em></h4>
7047 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Specify contents of <em>virtual pixels</em>.</td><td style='text-align:right;'></td></tr></table>
7049 <p>This option defines what color source should be used if and when a color
7050 lookup completely 'misses' the source image. The color(s) that appear to
7051 surround the source image. Generally this color is derived from the source
7052 image, but could also be set to a specify background color. </p>
7054 <p>Choose from these methods:</p>
7057 background the area surrounding the image is the background color
7058 black the area surrounding the image is black
7059 checker-tile alternate squares with image and background color
7060 dither non-random 32x32 dithered pattern
7061 edge extend the edge pixel toward infinity
7062 gray the area surrounding the image is gray
7063 horizontal-tile horizontally tile the image, background color above/below
7064 horizontal-tile-edge horizontally tile the image and replicate the side edge pixels
7065 mirror mirror tile the image
7066 random choose a random pixel from the image
7067 tile tile the image (default)
7068 transparent the area surrounding the image is transparent blackness
7069 vertical-tile vertically tile the image, sides are background color
7070 vertical-tile-edge vertically tile the image and replicate the side edge pixels
7071 white the area surrounding the image is white
7074 <p>The default value is "edge".</p>
7076 <p>This most important for distortion operators such as <a href="command-line-options.html#distort"
7077 >-distort</a>, <a href="command-line-options.html#implode" >-implode</a>, and <a href="command-line-options.html#fx" >-fx</a>.
7078 However it also effects operations that may access pixels just outside the
7079 image proper, such as <a href="command-line-options.html#convolve">-convolve</a>, <a
7080 href="command-line-options.html#blur">-blur</a>, and <a href="command-line-options.html#sharpen">-sharpen</a>. </p>
7082 <p>To print a complete list of virtual pixel types, use the <a
7083 href="command-line-options.html#list">-list virtual-pixel</a> option.</p>
7086 <div style="margin: auto;">
7087 <h4><a id="visual"></a>-visual <em class="arg">type</em></h4>
7090 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Animate images using this X visual type.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
7092 <p>Choose from these visual classes:</p>
7105 <p>The X server must support the visual you choose, otherwise an error occurs.
7106 If a visual is not specified, the visual class that can display the most
7107 simultaneous colors on the default screen is chosen.</p>
7110 <div style="margin: auto;">
7111 <h4><a id="watermark"></a>-watermark <em
7112 class="arg">brightness</em>x<em class="arg">saturation</em></h4>
7115 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Watermark an image using the given percentages of brightness and
7116 saturation.</td><td style='text-align:right;'>[<a href="composite.html">composite</a>]</td></tr></table>
7118 <p>Take a grayscale image (with alpha mask) and modify the destination image's
7119 brightness according to watermark image's grayscale value and the <em
7120 class="arg">brightness</em> percentage. The destinations color saturation
7121 attribute is just direct modified by the <em class="arg">saturation</em>
7122 percentage, which defaults to 100 percent (no color change). </p>
7125 <div style="margin: auto;">
7126 <h4><a id="wave"></a>-wave <em class="arg">amplitude</em><br />-wave <em class="arg">amplitude</em>x<em class="arg">wavelength</em></h4>
7129 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Shear the columns of an image into a sine wave.</td><td style='text-align:right;'></td></tr></table>
7131 <p>Specify <em class="arg">amplitude</em> and <em class="arg">wavelength</em>
7134 <div style="margin: auto;">
7135 <h4><a id="weight"></a>-weight <em class="arg">fontWeight</em></h4>
7138 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Set a font weight for text.</td><td style='text-align:right;'></td></tr></table>
7140 <p>This setting suggests a font weight that ImageMagick should try to apply to
7141 the currently selected font family. Use a positive integer for <em
7142 class="arg">fontWeight</em> or select from the following.</p>
7149 <th><em class="arg">fontWeight</em></th>
7150 <th>Description</th>
7155 <td>No effect. </td></tr>
7157 <td>Same as <em class="arg">fontWeight</em> = 700.</td></tr>
7158 <tr><td>Bolder </td>
7159 <td>Add 100 to font weight if currently ≤ 800.</td></tr>
7160 <tr><td>Lighter </td>
7161 <td>Subtract 100 to font weight if currently ≤ 100.</td></tr>
7162 <tr><td>Normal </td>
7163 <td>Same as <em class="arg">fontWeight</em> = 400.</td></tr>
7167 <p>To print a complete list of weight types, use <a href="command-line-options.html#list">-list
7170 <p>For other settings that affect fonts, see the options <a
7171 href="command-line-options.html#font">-font</a>, <a href="command-line-options.html#family">-family</a>, <a
7172 href="command-line-options.html#stretch">-stretch</a>, and <a href="command-line-options.html#style">-style</a>. </p>
7174 <div style="margin: auto;">
7175 <h4><a id="white-point"></a>-white-point <em class="arg">x,y</em></h4>
7178 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>chromaticity white point.</td><td style='text-align:right;'></td></tr></table>
7180 <div style="margin: auto;">
7181 <h4><a id="white-threshold"></a>-white-threshold <em class="arg">value</em>{<em class="arg">%</em>}</h4>
7184 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Force to white all pixels above the threshold while leaving all
7185 pixels at or below the threshold unchanged.</td><td style='text-align:right;'></td></tr></table>
7187 <p> The threshold value can be given as a percentage or as an absolute integer
7188 value within [0, <em class="QR">QuantumRange</em>] corresponding to the
7189 desired <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>
7191 <div style="margin: auto;">
7192 <h4><a id="window"></a>-window <em class="arg">id</em></h4>
7195 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>Make the image the background of a window.</td><td style='text-align:right;'>[<a href="animate.html">animate</a>, <a href="display.html">display</a>]</td></tr></table>
7197 <p><em class="arg">id</em> can be a window id or name. Specify <kbd>root</kbd>
7198 to select X's root window as the target window.</p>
7200 <p>By default the image is tiled onto the background of the target window. If
7201 <kbd>backdrop</kbd> or <a href="command-line-options.html#geometry">-resize</a> are specified, the
7202 image is surrounded by the background color. Refer to <kbd>X RESOURCES</kbd>
7205 <p>The image will not display on the root window if the image has more unique
7206 colors than the target window colormap allows. Use <a
7207 href="command-line-options.html#colors">-colors</a> to reduce the number of colors.</p>
7209 <div style="margin: auto;">
7210 <h4><a id="window-group"></a>-window-group</h4>
7213 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>specify the window group.</td><td style='text-align:right;'></td></tr></table>
7215 <div style="margin: auto;">
7216 <h4><a id="write"></a>-write <em class="arg">filename</em></h4>
7219 <table style='background-color:#FFFFE0; margin-left:40px; margin-right:40px; width:88%'><tr><td style='width:75%'>write an image sequence.</td><td style='text-align:right;'></td></tr></table>
7220 <p>The image sequence preceding the <a href="command-line-options.html#write">-write</a> <em class="arg">filename</em> 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> <em class="arg">filename</em> option.</p>
7222 <p>Use <a href="command-line-options.html#compress">-compress</a> to specify the type of image compression.</p>
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