/usr/share/doc/imagemagick/www/compare.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" 
  "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html version="-//W3C//DTD XHTML 1.1//EN"
      xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.w3.org/1999/xhtml
                          http://www.w3.org/MarkUp/SCHEMA/xhtml11.xsd">
<head>
  <meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
  <meta name="google-site-verification" content="MxsMq6bdLOx0KSuz1MY6yG9ZTIJ7_7DVRfl5NCAT5Yg"/>
  <title>ImageMagick: Command-line Tools: Compare</title>
  <meta http-equiv="content-language" content="en-US"/>
  <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
  <meta http-equiv="reply-to" content="magick-users@imagemagick.org"/>
  <meta name="application-name" content="ImageMagick"/>
  <meta name="description" content="Use ImageMagick to convert, edit, or compose bitmap images in a variety of formats.  In addition resize, rotate, shear, distort and transform images automagically."/>
  <meta name="application-url" content="http://www.imagemagick.org"/>
  <meta name="generator" content="PHP"/>
  <meta name="keywords" content="command-line, tools:, compare, ImageMagick, PerlMagick, image processing, OpenMP, software development library, image, photo, software, Magick++, MagickWand"/>
  <meta name="rating" content="GENERAL"/>
  <meta name="robots" content="INDEX, FOLLOW"/>
  <meta name="generator" content="ImageMagick Studio LLC"/>
  <meta name="author" content="ImageMagick Studio LLC"/>
  <meta name="revisit-after" content="2 DAYS"/>
  <meta name="resource-type" content="document"/>
  <meta name="copyright" content="Copyright (c) 1999-2012 ImageMagick Studio LLC"/>
  <meta name="distribution" content="Global"/>
  <link rel="icon" href="../images/wand.png"/>
  <link rel="shortcut icon" href="../images/wand.ico"  type="images/x-icon"/>
  <link rel="canonical" href="http://www.imagemagick.org" />
  <link rel="meta" type="application/rdf+xml" title="ICI" href="http://imagemagick.org/ici.rdf"/>
  <!-- Add jQuery library -->
  <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js"></script>
  
  <!-- Optionaly include easing and/or mousewheel plugins -->
  <script type="text/javascript" src="http://www.imagemagick.org/fancybox/jquery.easing-1.3.pack.js"></script>
  <script type="text/javascript" src="http://www.imagemagick.org/fancybox/jquery.mousewheel-3.0.6.pack.js"></script>
  
  <!-- Add fancyBox -->
  <link rel="stylesheet" href="http://www.imagemagick.org/fancybox/jquery.fancybox.css?v=2.0.4" type="text/css" media="screen" />
  <script type="text/javascript" src="http://www.imagemagick.org/fancybox/jquery.fancybox.pack.js?v=2.0.4"></script>
  
  <!-- Optionaly include button and/or thumbnail helpers -->
  <link rel="stylesheet" href="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-buttons.css?v=2.0.4" type="text/css" media="screen" />
  <script type="text/javascript" src="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-buttons.js?v=2.0.4"></script>
  
  <link rel="stylesheet" href="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-thumbs.css?v=2.0.4" type="text/css" media="screen" />
  <script type="text/javascript" src="http://www.imagemagick.org/fancybox/helpers/jquery.fancybox-thumbs.js?v=2.0.4"></script>
  <script type="text/javascript">
  	$(document).ready(function() {
  		$(".fancybox").fancybox();
  	});
  </script>
  <!-- ImageMagick style -->
  <link rel="stylesheet" href="http://www.google.com/cse/style/look/default.css" type="text/css" />
  <style type="text/css" media="all">
    @import url("../www/magick.css");
  </style>
</head>

<body id="www-imagemagick-org">
<div class="titlebar">
<div style="margin: 17px auto; float: left;">
  <script type="text/javascript">
  <!--
    google_ad_client = "pub-3129977114552745";
    google_ad_slot = "5439289906";
    google_ad_width = 728;
    google_ad_height = 90;
  //-->
  </script>
  <script type="text/javascript"
    src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
  </script>
</div>
<a href="../discourse-server">
  <img src="../images/logo.jpg"
  alt="ImageMagick Logo"
  style="width: 123px; height: 118px; border: 0px; float: right;" /></a>
<a href="../index.html">
  <img src="../images/sprite.jpg"
  alt="ImageMagick Sprite"
  style="width: 114px; height: 118px; border: 0px; float: right;" /></a>
</div>

<div class="westbar">

<div class="menu">
  <a title="About ImageMagick" href="../index.html">About ImageMagick</a>
</div>
<div class="menu">
  <a title="Binary Releases" href="binary-releases.html">Binary Releases</a>
</div>
<div class="sub">
    <a title="Binary Release: Unix" href="binary-releases.html#unix">Unix</a>
</div>
<div class="sub">
    <a title="Binary Release: MacOS X" href="binary-releases.html#macosx">Mac OS X</a>
</div>
<div class="sub">
    <a title="Binary Release: iOS" href="binary-releases.html#iOS">iOS</a>
</div>
<div class="sub">
    <a title="Binary Release: Windows" href="binary-releases.html#windows">Windows</a>
</div>
<div class="sep"></div>
<div class="menu">
  <a title="Command-line Tools" href="command-line-tools.html">Command-line Tools</a>
</div>
<div class="sub">
    <a title="Command-line Tools: Processing" href="command-line-processing.html">Processing</a>
</div>
<div class="sub">
    <a title="Command-line Tools: Options" href="command-line-options.html">Options</a>
</div>
<div class="sub">
    <a title="Command-line Tools: Usage" href="http://www.imagemagick.org/Usage/">Usage</a>
</div>
<div class="menu">
  <a title="Program Interfaces" href="api.html">Program Interfaces</a>
</div>
<div class="sub">
    <a title="Program Interface: MagickWand" href="magick-wand.html">MagickWand</a>
</div>
<div class="sub">
    <a title="Program Interface: MagickCore" href="magick-core.html">MagickCore</a>
</div>
<div class="sub">
    <a title="Program Interface: PerlMagick" href="perl-magick.html">PerlMagick</a>
</div>
<div class="sub">
    <a title="Program Interface: Magick++" href="magick++.html">Magick++</a>
</div>
<div class="sep"></div>
<div  class="menu">
   <a title="Install from Source" href="install-source.html">Install from Source</a>
</div>
<div class="sub">
    <a title="Install from Source: Unix" href="install-source.html#unix">Unix</a>
</div>
<div class="sub">
    <a title="Install from Source: Windows" href="install-source.html#windows">Windows</a>
 </div>
<div class="menu">
  <a title="Resources" href="resources.html">Resources</a>
</div>
<div class="menu">
  <a title="Architecture" href="architecture.html">Architecture</a>
</div>
<div class="menu">
  <a title="Download" href="download.html">Download</a>
</div>
<div class="sep"></div>
<div class="menu">
  <a title="Search" href="search.html">Search</a>
</div>
<div class="sep"></div>
<div class="menu">
  <a title="Site Map" href="sitemap.html">Site Map</a>
</div>
<div  class="sub">
  <a title="Site Map: Links" href="links.html">Links</a>
</div>
<div class="sep"></div>
<div class="menu">
  <a rel="follow" title="Sponsors" href="sponsors.html">Sponsors:</a>

  <a href="http://www.networkredux.com"> <img src="../images/networkredux.png" width="140" height="31" alt="[sponsor]" style="margin-top: 4px; margin-left: 4px; border: 0px; float: left;" /></a>
  <a href="http://www.dinodirect.com/ipads-tablets/"> <img src="../images/dino-direct.jpg" width="140" height="90" alt="[sponsor]" style="margin-top: 4px; margin-left: 4px; border: 0px; float: left;" /></a><!-- 201208010120 mickey@163... -->
<div class="sponsbox">
<div class="sponsor">
  <a rel="follow" title="Sponsor: The Fastest &amp; Easiest Way to Find Images" href="http://www.graphicsfactory.com">The Fastest &amp; Easiest Way to Find Images</a><!-- 201210010270 graphicsfac... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Sponsor: VPS" href="http://www.interdominios.com/vps">VPS</a><!-- 201209010090 barsh@inter... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Werbebanner Werbeplane" href="http://www.allesbanner.de">Werbebanner Werbeplane</a><!-- 201212010450 info@druck... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Entertainment News &amp; Photos" href="http://www.zimbio.com">Entertainment News &amp; Photos</a><!-- 201211010540 bd@zimb... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Sponsor: LED24" href="http://led24.de/">LED24</a><!-- 201207010270 info@led24... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Sponsor: Best Website Hosting" href="http://www.top-cheap-web-hosting.com">Best Website Hosting</a><!-- 201304010090 eunge.liu-->
</div>
<div class="sponsor">
  <a rel="follow" title="Android Tablet" href="http://www.dinodirect.com/ipads-tablets/">Android Tablet</a><!-- 201208010120 mickey@163... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Sponsor: Web Site Hosting" href="http://webhostinggeeks.com">Web Site Hosting</a><!-- 201302010900 funds@enmob... -->
</div>
<div class="sponsor">
   <a rel="follow" title="Sponsor: Premium Quality Stock Photos" href="http://www.f1online.pro/en/">Premium Quality Stock Photos</a><!-- 2012080100540 ... -->
</div>
<div class="sponsor">
   <a rel="follow" title="Sponsor: Druckerei" href="http://print24.com/de/">Druckerei</a><!-- 2012070100250 ... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Sponsor: Managed Server" href="http://www.robhost.de">Managed Server</a><!-- 201210010720 klikics... -->
</div>
<div class="sponsor">
  <a rel="follow" title="Sponsor: Druckerei" href="http://www.allesdruck.de">Druckerei</a><!-- 201303011500 r.leo -->
</div>
<div class="sponsor">
   <a rel="follow" title="Sponsor: Names List" href="http://www.listofnames.info">Names List</a><!-- 2012110100180 grimshrat@busyb-->
</div>
<div class="sponsor">
   <a rel="follow" title="Sponsor: Waschmaschinen Reparatur Berlin" href="http://www.waschmaschinen-reparaturen-berlin.de">Waschmaschinen Reparatur Berlin</a><!-- 2012070100030 Temurbas@autoteile-->
</div>
</div>
</div>
</div>

<div class="eastbar">
  <div class="g-plusone" id="gplusone"></div>
  <script type="text/javascript">
    window.___gcfg = {
      lang: 'en-US'
    };

    (function() {
      var po = document.createElement('script');
      po.type = 'text/javascript'; po.async = true;
      po.src = 'https://apis.google.com/js/plusone.js';
      var script = document.getElementsByTagName('script')[0];
      script.parentNode.insertBefore(po, script);
    })();
    var gplusone = document.getElementById("gplusone");
    gplusone.setAttribute("data-size","medium");
    gplusone.setAttribute("data-count","false");
  </script>
</div>

<div class="main">

<h1>ImageMagick Compare Command-line Tool</h1>
<p class="navigation-index">[<a href="compare.html#usage">Example Usage</a> &bull; <a href="compare.html#options">Option Summary</a>]</p>

<div class="doc-section">
<p>Use the <kbd>compare</kbd> program to mathematically and visually annotate the difference between an image and its reconstruction.  See <a href="command-line-processing.html">Command Line Processing</a> for advice on how to structure your <kbd>compare</kbd> command or see below for example usages of the command.</p>
</div>

<h2><a id="usage"></a>Example Usage</h2>
<div class="doc-section">

<p>We list a few examples of the <kbd>compare</kbd> command here to illustrate its usefulness and ease of use. To get started, lets compare an image to one thats been sharpened:</p>

<p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>convert rose.jpg -sharpen 0x1 reconstruct.jpg</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>compare rose.jpg reconstruct.jpg difference.png</span><span class='crtout'></span><span class="crtprompt"> $ </span><span class='crtin'>compare -compose src rose.jpg reconstruct.jpg difference.png</span></p>
<div class="image">
<p>
  <a href="../images/rose.jpg"><img src="../images/rose.jpg" width="70" height="46" alt="rose" /></a>
  <a href="../images/reconstruct.jpg"><img src="../images/reconstruct.jpg" width="70" height="46" alt="rose" /></a>
  <img style="margin:13px 0;" src="../images/right.gif" width="20" height="20" alt="==>" />
  <a href="../images/difference.png"><img src="../images/difference.png" width="70" height="46" alt="rose" /></a>
</p>
</div>

<p>The red areas of the difference image emphasizes (highlight) pixels that are affected by the image sharpening, whereas white de-emphasizes (lowlight) pixels that are untouched by the sharpening process.</p>

<p>In addition to the visual interpretation of the difference in an image and its reconstruction, we report a mathematical measure of the difference:</p>

<p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>compare -verbose -metric mae rose.jpg reconstruct.jpg difference.png</span><span class='crtout'>Image: rose.jpg     <br/>
    Channel distortion: MAE     <br/>
      red: 2282.91 (0.034835)     <br/>
      green: 1853.99 (0.0282901)     <br/>
      blue: 2008.67 (0.0306503)     <br/>
      all: 1536.39 (0.0234439)     <br/></span></p><p>Or, if you just want the red channel distortion, use this command:</p>

<p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>compare -channel red -metric PSNR rose.jpg reconstruct.jpg difference.png</span><span class='crtout'>19.63</span></p>
<p>Or, if you just want the overall image distortion, use this command:</p>

<p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>compare -metric PSNR rose.jpg reconstruct.jpg difference.png</span><span class='crtout'>28.31</span></p>
<p>If the reconstructed image is a subimage of the image, the compare program returns the best match offset.  In addition, it returns a similarity image such that an exact match location is completely white and if none of the pixels match, black, otherwise some gray level in-between:</p>

<p class='crt'><span class="crtprompt"> $ </span><span class='crtin'>compare -metric RMSE -subimage-search logo.png wizard.jpg similarity.gif</span><span class='crtout'>85.05 (0.00129778) @ 353,157</span></p>
<p>You can find additional examples of using <kbd>compare</kbd> in <a href="http://www-106.ibm.com/developerworks/library/l-graf/?ca=dnt-428">Graphics from the Command Line</a>.  Further discussion is available in <a href="http://www-106.ibm.com/developerworks/library/l-graf2/?ca=dgr-lnxw15GraphicsLine">More Graphics from the Command Line</a> and <a href="http://www.imagemagick.org/Usage/">Examples of ImageMagick Usage</a>.</p>
</div>

<h2><a id="options"></a>Option Summary</h2>
<div class="doc-section">

<p>The <kbd>compare</kbd> command recognizes these options.  Click on an option to get more details about how that option works.</p>

<table class="doc">
  <tbody>
  <tr>
    <th align="left">Option</th>
    <th align="left">Description</th>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#alpha">-alpha</a></td>
    <td valign="top">on, activate, off, deactivate, set, opaque, copy",
transparent, extract, background, or shape the alpha channel</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#authenticate">-authenticate <em class="option">value</em></a></td>
    <td valign="top">decrypt image with this password</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#channel">-channel <em class="option">type</em></a></td>
    <td valign="top">apply option to select image channels</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#colorspace">-colorspace <em class="option">type</em></a></td>
    <td valign="top">set image colorspace</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#compose">-compose <em class="option">operator</em></a></td>
    <td valign="top">set image composite operator</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#decipher">-decipher <em class="option">filename</em></a></td>
    <td valign="top">convert cipher pixels to plain</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#debug">-debug <em class="option">events</em></a></td>
    <td valign="top">display copious debugging information</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#define">-define <em class="option">format:option</em></a></td>
    <td valign="top">define one or more image format options</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#density">-density <em class="option">geometry</em></a></td>
    <td valign="top">horizontal and vertical density of the image</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#depth">-depth <em class="option">value</em></a></td>
    <td valign="top">image depth</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#disimilarity-threshold">-disimilarity-threshold <em class="option">value</em></a></td>
    <td valign="top">maximum distortion for (sub)image match (default 0.2)</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#encipher">-encipher <em class="option">filename</em></a></td>
    <td valign="top">convert plain pixels to cipher pixels</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#extract">-extract <em class="option">geometry</em></a></td>
    <td valign="top">extract area from image</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#fuzz">-fuzz <em class="option">distance</em></a></td>
    <td valign="top">colors within this distance are considered equal</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#help">-help</a></td>
    <td valign="top">print program options</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#highlight-color">-highlight-color <em class="option">color</em></a></td>
    <td valign="top">emphasize pixel differences with this color</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#identify">-identify</a></td>
    <td valign="top">identify the format and characteristics of the image</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#interlace">-interlace <em class="option">type</em></a></td>
    <td valign="top">type of image interlacing scheme</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#limit">-limit <em class="option">type value</em></a></td>
    <td valign="top">pixel cache resource limit</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#log">-log <em class="option">format</em></a></td>
    <td valign="top">format of debugging information</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#lowlight-color">-lowlight-color <em class="option">color</em></a></td>
    <td valign="top">de-emphasize pixel differences with this color</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#metric">-metric <em class="option">type</em></a></td>
    <td valign="top">measure differences between images with this metric</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#profile">-profile <em class="option">filename</em></a></td>
    <td valign="top">add, delete, or apply an image profile</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#quality">-quality <em class="option">value</em></a></td>
    <td valign="top">JPEG/MIFF/PNG compression level</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#quantize">-quantize <em class="option">colorspace</em></a></td>
    <td valign="top">reduce image colors in this colorspace</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#quiet">-quiet</a></td>
    <td valign="top">suppress all warning messages</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#regard-warnings">-regard-warnings</a></td>
    <td valign="top">pay attention to warning messages.</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#respect-parentheses">-respect-parentheses</a></td>
    <td valign="top">settings remain in effect until parenthesis boundary.</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#sampling-factor">-sampling-factor <em class="option">geometry</em></a></td>
    <td valign="top">horizontal and vertical sampling factor</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#seed">-seed <em class="option">value</em></a></td>
    <td valign="top">seed a new sequence of pseudo-random numbers</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#set">-set <em class="option">attribute value</em></a></td>
    <td valign="top">set an image attribute</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#size">-size <em class="option">geometry</em></a></td>
    <td valign="top">width and height of image</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#subimage-search">-subimage-search</a></td>
    <td valign="top">search for subimage</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#synchronize">-synchronize</a></td>
    <td valign="top">synchronize image to storage device</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#taint">-taint</a></td>
    <td valign="top">mark the image as modified</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#transparent-color">-transparent-color <em class="option">color</em></a></td>
    <td valign="top">transparent color</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#verbose">-verbose</a></td>
    <td valign="top">print detailed information about the image</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#version">-version</a></td>
    <td valign="top">print version information</td>
  </tr>

  <tr>
    <td valign="top"><a href="command-line-options.html#virtual-pixel">-virtual-pixel <em class="option">method</em></a></td>
    <td valign="top">access method for pixels outside the boundaries of the image</td>
  </tr>

  </tbody>
</table>
</div>

</div>

<div id="linkbar">
    <span id="linkbar-west">&nbsp;</span>
    <span id="linkbar-center">
      <a href="../discourse-server">Discourse Server</a> &bull;
      <a href="http://www.imagemagick.org/MagickStudio/scripts/MagickStudio.cgi">Studio</a>
    </span>
    <span id="linkbar-east">&nbsp;</span>
  </div>
  <div class="footer">
    <span id="footer-west">&copy; 1999-2012 ImageMagick Studio LLC</span>
    <span id="footer-east"> <a href="contact.html">Contact the Wizards</a></span>
  </div>
  <div style="clear: both; margin: 0; width: 100%; "></div>
  <script type="text/javascript">
    var _gaq = _gaq || [];
    _gaq.push(['_setAccount', 'UA-17690367-1']);
    _gaq.push(['_trackPageview']);

    (function() {
      var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
      ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
      var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
    })();
  </script>
</body>
</html>
imagemagick-doc 8:6.7.7.10-6ubuntu3 / usr / share / doc / imagemagick / www / compare.html
