Home | History | Annotate | Download | only in www
      1 
      2 
      3 
      4 
      5 <!DOCTYPE html>
      6 <html lang="en">
      7 <head>
      8     <title>ImageMagick: Command-line Tools: Compare</title>
      9   <meta charset="utf-8" />
     10   <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     11   <meta name="viewport" content="width=device-width, initial-scale=1" />
     12   <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
     13   <meta name="application-name" content="ImageMagick"/>
     14   <meta name="description" content="ImageMagick is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 200) including PNG, JPEG, JPEG-2000, GIF, WebP, Postscript, PDF, and SVG. Use ImageMagick to resize, flip, mirror, rotate, distort, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bzier curves."/>
     15   <meta name="application-url" content="http://www.imagemagick.org"/>
     16   <meta name="generator" content="PHP"/>
     17   <meta name="keywords" content="command-line, tools:, compare, ImageMagick, PerlMagick, image processing, image, photo, software, Magick++, OpenMP, convert"/>
     18   <meta name="rating" content="GENERAL"/>
     19   <meta name="robots" content="INDEX, FOLLOW"/>
     20   <meta name="generator" content="ImageMagick Studio LLC"/>
     21   <meta name="author" content="ImageMagick Studio LLC"/>
     22   <meta name="revisit-after" content="2 DAYS"/>
     23   <meta name="resource-type" content="document"/>
     24   <meta name="copyright" content="Copyright (c) 1999-2016 ImageMagick Studio LLC"/>
     25   <meta name="distribution" content="Global"/>
     26   <meta name="magick-serial" content="P131-S030410-R485315270133-P82224-A6668-G1245-1"/>
     27   <meta name="google-site-verification" content="_bMOCDpkx9ZAzBwb2kF3PRHbfUUdFj2uO8Jd1AXArz4" />
     28   <link rel="icon" href="../images/wand.png"/>
     29   <link rel="shortcut icon" href="../images/wand.ico"/>
     30   <link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=Roboto:900,400,400italic,700,700italic,300,300italic|Open+Sans:300italic,400italic,700italic,300,400,600,700">
     31   <link rel="stylesheet" href="css/magick.css"/>
     32 </head>
     33 <body>
     34 <div class="main">
     35 <div class="magick-masthead">
     36   <div class="container">
     37     <script async="async" src="http://localhost/pagead/js/adsbygoogle.js"></script>    <ins class="adsbygoogle"
     38          style="display:block"
     39          data-ad-client="ca-pub-3129977114552745"
     40          data-ad-slot="6345125851"
     41          data-ad-format="auto"></ins>
     42     <script>
     43       (adsbygoogle = window.adsbygoogle || []).push({});
     44     </script>
     45     <nav class="magick-nav">
     46       <a class="magick-nav-item " href="../index.html">Home</a>
     47       <a class="magick-nav-item " href="binary-releases.html">Download</a>
     48       <a class="magick-nav-item " href="command-line-tools.html">Tools</a>
     49       <a class="magick-nav-item " href="command-line-processing.html">Command-line</a>
     50       <a class="magick-nav-item " href="resources.html">Resources</a>
     51       <a class="magick-nav-item " href="api.html">Develop</a>
     52       <a class="magick-nav-item " href="http://www.imagemagick.org/script/search.php">Search</a>
     53       <a class="magick-nav-item pull-right" href="https://www.imagemagick.org/discourse-server/">Community</a>
     54     </nav>
     55   </div>
     56 </div>
     57 <div class="container">
     58 <div class="magick-header">
     59 <p class="text-center"><a href="compare.html#usage">Example Usage</a>  <a href="compare.html#options">Option Summary</a></p>
     60 
     61 <p class="lead magick-description">Use the <code>compare</code> 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 <code>compare</code> command or see below for example usages of the command.</p>
     62 
     63 <h2 class="magick-header"><a id="usage"></a>Example Usage</h2>
     64 
     65 <p>We list a few examples of the <code>compare</code> command here to illustrate its usefulness and ease of use. To get started, lets compare an image to one thats been sharpened:</p>
     66 
     67 <pre>
     68 convert rose.jpg -sharpen 0x1 reconstruct.jpg
     69 compare rose.jpg reconstruct.jpg difference.png
     70 compare -compose src rose.jpg reconstruct.jpg difference.png
     71 </pre>
     72 
     73 <ul>
     74   <a href="../images/rose.jpg"><img src="../images/rose.jpg" width="70" height="46" alt="rose" /></a>
     75   <a href="../images/reconstruct.jpg"><img src="../images/reconstruct.jpg" width="70" height="46" alt="rose" /></a>
     76   <img style="margin:13px 0;" src="../images/right.gif" width="20" height="20" alt="==>" />
     77   <a href="../images/difference.png"><img src="../images/difference.png" width="70" height="46" alt="rose" /></a>
     78 </ul>
     79 
     80 <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>
     81 
     82 <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>
     83 
     84 <pre>
     85 -> compare -verbose -metric mae rose.jpg reconstruct.jpg difference.png
     86 Image: rose.jpg
     87  Channel distortion: MAE
     88   red: 2282.91 (0.034835)
     89   green: 1853.99 (0.0282901)
     90   blue: 2008.67 (0.0306503)
     91   all: 1536.39 (0.0234439)
     92 </pre>
     93 <p>Or, if you just want the red channel distortion, use this command:</p>
     94 
     95 <pre>
     96 -> compare -channel red -metric PSNR rose.jpg reconstruct.jpg difference.png
     97 19.63
     98 </pre>
     99 
    100 <p>Or, if you just want the overall image distortion, use this command:</p>
    101 
    102 <pre>
    103 -> compare -metric PSNR rose.jpg reconstruct.jpg difference.png
    104 28.31
    105 </pre>
    106 
    107 <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>
    108 
    109 <pre>
    110 -> compare -metric RMSE -subimage-search logo.png wizard.jpg similarity.gif
    111 85.05 (0.00129778) @ 353,157
    112 </pre>
    113 
    114 <p>You can find additional examples of using <code>compare</code> in <a href="http://www.ibm.com/developerworks/library/l-graf/?ca=dnt-428">Graphics from the Command Line</a>.  Further discussion is available in <a href="http://www.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>
    115 
    116 <p>The compare program returns 2 on error otherwise 0 if the images are similar or 1 if they are dissimilar.</p>
    117 
    118 <h2 class="magick-header"><a id="options"></a>Option Summary</h2>
    119 
    120 <p>The <code>compare</code> command recognizes these options.  Click on an option to get more details about how that option works.</p>
    121 
    122 <table class="table table-condensed table-striped">
    123   <tbody>
    124   <tr>
    125     <th align="left">Option</th>
    126     <th align="left">Description</th>
    127   </tr>
    128 
    129   <tr>
    130     <td><a href="command-line-options.html#alpha">-alpha</a></td>
    131     <td>on, activate, off, deactivate, set, opaque, copy",
    132 transparent, extract, background, or shape the alpha channel</td>
    133   </tr>
    134 
    135   <tr>
    136     <td><a href="command-line-options.html#authenticate">-authenticate <var>value</var></a></td>
    137     <td>decrypt image with this password</td>
    138   </tr>
    139 
    140   <tr>
    141     <td><a href="command-line-options.html#channel">-channel <var>type</var></a></td>
    142     <td>apply option to select image channels</td>
    143   </tr>
    144 
    145   <tr>
    146     <td><a href="command-line-options.html#colorspace">-colorspace <var>type</var></a></td>
    147     <td>set image colorspace</td>
    148   </tr>
    149 
    150   <tr>
    151     <td><a href="command-line-options.html#compose">-compose <var>operator</var></a></td>
    152     <td>set image composite operator</td>
    153   </tr>
    154 
    155   <tr>
    156     <td><a href="command-line-options.html#decipher">-decipher <var>filename</var></a></td>
    157     <td>convert cipher pixels to plain</td>
    158   </tr>
    159 
    160   <tr>
    161     <td><a href="command-line-options.html#debug">-debug <var>events</var></a></td>
    162     <td>display copious debugging information</td>
    163   </tr>
    164 
    165   <tr>
    166     <td><a href="command-line-options.html#define">-define <var>format:option</var></a></td>
    167     <td>define one or more image format options</td>
    168   </tr>
    169 
    170   <tr>
    171     <td><a href="command-line-options.html#density">-density <var>geometry</var></a></td>
    172     <td>horizontal and vertical density of the image</td>
    173   </tr>
    174 
    175   <tr>
    176     <td><a href="command-line-options.html#depth">-depth <var>value</var></a></td>
    177     <td>image depth</td>
    178   </tr>
    179 
    180   <tr>
    181     <td><a href="command-line-options.html#dissimilarity-threshold">-dissimilarity-threshold <var>value</var></a></td>
    182     <td>maximum distortion for (sub)image match (default 0.2)</td>
    183   </tr>
    184 
    185   <tr>
    186     <td><a href="command-line-options.html#encipher">-encipher <var>filename</var></a></td>
    187     <td>convert plain pixels to cipher pixels</td>
    188   </tr>
    189 
    190   <tr>
    191     <td><a href="command-line-options.html#extract">-extract <var>geometry</var></a></td>
    192     <td>extract area from image</td>
    193   </tr>
    194 
    195   <tr>
    196     <td><a href="command-line-options.html#fuzz">-fuzz <var>distance</var></a></td>
    197     <td>colors within this distance are considered equal</td>
    198   </tr>
    199 
    200   <tr>
    201     <td><a href="command-line-options.html#help">-help</a></td>
    202     <td>print program options</td>
    203   </tr>
    204 
    205   <tr>
    206     <td><a href="command-line-options.html#highlight-color">-highlight-color <var>color</var></a></td>
    207     <td>emphasize pixel differences with this color</td>
    208   </tr>
    209 
    210   <tr>
    211     <td><a href="command-line-options.html#identify">-identify</a></td>
    212     <td>identify the format and characteristics of the image</td>
    213   </tr>
    214 
    215   <tr>
    216     <td><a href="command-line-options.html#interlace">-interlace <var>type</var></a></td>
    217     <td>type of image interlacing scheme</td>
    218   </tr>
    219 
    220   <tr>
    221     <td><a href="command-line-options.html#limit">-limit <var>type value</var></a></td>
    222     <td>pixel cache resource limit</td>
    223   </tr>
    224 
    225   <tr>
    226     <td><a href="command-line-options.html#log">-log <var>format</var></a></td>
    227     <td>format of debugging information</td>
    228   </tr>
    229 
    230   <tr>
    231     <td><a href="command-line-options.html#lowlight-color">-lowlight-color <var>color</var></a></td>
    232     <td>de-emphasize pixel differences with this color</td>
    233   </tr>
    234 
    235   <tr>
    236     <td><a href="command-line-options.html#metric">-metric <var>type</var></a></td>
    237     <td>measure differences between images with this metric</td>
    238   </tr>
    239 
    240   <tr>
    241     <td><a href="command-line-options.html#profile">-profile <var>filename</var></a></td>
    242     <td>add, delete, or apply an image profile</td>
    243   </tr>
    244 
    245   <tr>
    246     <td><a href="command-line-options.html#quality">-quality <var>value</var></a></td>
    247     <td>JPEG/MIFF/PNG compression level</td>
    248   </tr>
    249 
    250   <tr>
    251     <td><a href="command-line-options.html#quantize">-quantize <var>colorspace</var></a></td>
    252     <td>reduce image colors in this colorspace</td>
    253   </tr>
    254 
    255   <tr>
    256     <td><a href="command-line-options.html#quiet">-quiet</a></td>
    257     <td>suppress all warning messages</td>
    258   </tr>
    259 
    260   <tr>
    261     <td><a href="command-line-options.html#regard-warnings">-regard-warnings</a></td>
    262     <td>pay attention to warning messages.</td>
    263   </tr>
    264 
    265   <tr>
    266     <td><a href="command-line-options.html#respect-parentheses">-respect-parentheses</a></td>
    267     <td>settings remain in effect until parenthesis boundary.</td>
    268   </tr>
    269 
    270   <tr>
    271     <td><a href="command-line-options.html#sampling-factor">-sampling-factor <var>geometry</var></a></td>
    272     <td>horizontal and vertical sampling factor</td>
    273   </tr>
    274 
    275   <tr>
    276     <td><a href="command-line-options.html#seed">-seed <var>value</var></a></td>
    277     <td>seed a new sequence of pseudo-random numbers</td>
    278   </tr>
    279 
    280   <tr>
    281     <td><a href="command-line-options.html#set">-set <var>attribute value</var></a></td>
    282     <td>set an image attribute</td>
    283   </tr>
    284 
    285   <tr>
    286     <td><a href="command-line-options.html#similarity-threshold">-similarity-threshold <var>value</var></a></td>
    287     <td>minimum distortion for (sub)image match (default 0.0)</td>
    288   </tr>
    289 
    290   <tr>
    291     <td><a href="command-line-options.html#size">-size <var>geometry</var></a></td>
    292     <td>width and height of image</td>
    293   </tr>
    294 
    295   <tr>
    296     <td><a href="command-line-options.html#subimage-search">-subimage-search</a></td>
    297     <td>search for subimage</td>
    298   </tr>
    299 
    300   <tr>
    301     <td><a href="command-line-options.html#synchronize">-synchronize</a></td>
    302     <td>synchronize image to storage device</td>
    303   </tr>
    304 
    305   <tr>
    306     <td><a href="command-line-options.html#taint">-taint</a></td>
    307     <td>mark the image as modified</td>
    308   </tr>
    309 
    310   <tr>
    311     <td><a href="command-line-options.html#transparent-color">-transparent-color <var>color</var></a></td>
    312     <td>transparent color</td>
    313   </tr>
    314 
    315   <tr>
    316     <td><a href="command-line-options.html#verbose">-verbose</a></td>
    317     <td>print detailed information about the image</td>
    318   </tr>
    319 
    320   <tr>
    321     <td><a href="command-line-options.html#version">-version</a></td>
    322     <td>print version information</td>
    323   </tr>
    324 
    325   <tr>
    326     <td><a href="command-line-options.html#virtual-pixel">-virtual-pixel <var>method</var></a></td>
    327     <td>access method for pixels outside the boundaries of the image</td>
    328   </tr>
    329 
    330   </tbody>
    331 </table>
    332 </div>
    333   <footer class="magick-footer">
    334     <p><a href="support.html">Donate</a> 
    335      <a href="sitemap.html">Sitemap</a> 
    336     <a href="links.html">Related</a> 
    337     <a href="architecture.html">Architecture</a>
    338 </p>
    339     <p><a href="compare.html#">Back to top</a> 
    340     <a href="http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x89AB63D48277377A">Public Key</a> 
    341     <a href="http://www.imagemagick.org/script/contact.php">Contact Us</a></p>
    342         <p><small>  1999-2016 ImageMagick Studio LLC</small></p>
    343   </footer>
    344 </div><!-- /.container -->
    345 
    346   <script src="https://localhost/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
    347   <script src="../js/magick.html"></script>
    348 </div>
    349 </body>
    350 </html>
    351 <!-- Magick Cache 17th June 2016 14:42 -->