home *** CD-ROM | disk | FTP | other *** search
/ Mac Easy 2010 May / Mac Life Ubuntu.iso / casper / filesystem.squashfs / usr / share / gimp / 2.0 / help / en / plug-in-rgb-noise.html < prev    next >
Encoding:
Extensible Markup Language  |  2008-05-03  |  8.9 KB  |  229 lines
  1. <?xml version="1.0" encoding="UTF-8" standalone="no"?>
  2. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  3. <html xmlns="http://www.w3.org/1999/xhtml">
  4.   <head>
  5.     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  6.     <title>3.3.¬† RGB Noise</title>
  7.     <link rel="stylesheet" href="gimp-help-plain.css" type="text/css" />
  8.     <link rel="stylesheet" href="gimp-help-screen.css" type="text/css" />
  9.     <link rel="stylesheet" href="gimp-help-custom.css" type="text/css" />
  10.     <link rel="alternate stylesheet" href="gimp22.css" type="text/css" title="gimp22" />
  11.     <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
  12.     <link rel="start" href="index.html" title="GNU Image Manipulation Program" />
  13.     <link rel="up" href="filters-noise.html" title="3.¬† Noise Filters" />
  14.     <link rel="prev" href="plug-in-randomize-hurl.html" title="3.2.¬† Hurl" />
  15.     <link rel="next" href="plug-in-randomize-pick.html" title="3.4.¬† Pick" />
  16.   </head>
  17.   <body>
  18.     <div class="navheader">
  19.       <table width="100%" summary="Navigation header">
  20.         <tr>
  21.           <th colspan="3" align="center">3.3.¬†
  22.     <span lang="en" xml:lang="en">RGB Noise</span>
  23.   </th>
  24.         </tr>
  25.         <tr>
  26.           <td width="20%" align="left"><a accesskey="p" href="plug-in-randomize-hurl.html"><img src="../images/prev.png" alt="Prev" /></a>¬†</td>
  27.           <th width="60%" align="center">3.¬†
  28.     <span lang="en" xml:lang="en">Noise Filters</span>
  29.   </th>
  30.           <td width="20%" align="right">¬†<a accesskey="n" href="plug-in-randomize-pick.html"><img src="../images/next.png" alt="Next" /></a></td>
  31.         </tr>
  32.       </table>
  33.       <hr />
  34.     </div>
  35.     <div class="sect2" lang="en" xml:lang="en">
  36.       <div class="titlepage">
  37.         <div>
  38.           <div>
  39.             <h3 class="title"><a id="plug-in-rgb-noise"></a>3.3.¬†
  40.     <span lang="en" xml:lang="en">RGB Noise</span>
  41.   </h3>
  42.           </div>
  43.           <div>
  44.             <div class="revhistory">
  45.               <table border="1" width="100%" summary="Revision history">
  46.                 <tr>
  47.                   <th align="left" valign="top" colspan="3">
  48.                     <b>Revision History</b>
  49.                   </th>
  50.                 </tr>
  51.                 <tr>
  52.                   <td align="left">Revision $Revision: 2436 $</td>
  53.                   <td align="left">2007-08-06</td>
  54.                   <td align="left">ude</td>
  55.                 </tr>
  56.               </table>
  57.             </div>
  58.           </div>
  59.         </div>
  60.       </div>
  61.       <a id="id2733364" class="indexterm"></a>
  62.       <a id="id2733382" class="indexterm"></a>
  63.       <div class="sect3" lang="en" xml:lang="en">
  64.         <div class="titlepage">
  65.           <div>
  66.             <div>
  67.               <h4 class="title"><a id="id2733390"></a>3.3.1.¬†
  68.       <span lang="en" xml:lang="en">Overview</span>
  69.     </h4>
  70.             </div>
  71.           </div>
  72.         </div>
  73.         <div class="figure">
  74.           <a id="id2733401"></a>
  75.           <p class="title">
  76.             <b>Figure¬†16.21.¬†
  77.         <span lang="en" xml:lang="en">Example of applying the Noisify filter</span>
  78.       </b>
  79.           </p>
  80.           <div class="figure-contents">
  81.             <div class="mediaobject">
  82.               <img src="../images/filters/examples/taj_orig.jpg" alt="Example of applying the Noisify filter" />
  83.               <div class="caption">
  84.                 <p>Original image</p>
  85.               </div>
  86.             </div>
  87.             <div class="mediaobject">
  88.               <img src="../images/filters/examples/noise-taj-scatter-rgb.jpg" alt="Example of applying the Noisify filter" />
  89.               <div class="caption">
  90.                 <p>Filter ‚Äú<span class="quote">RGB Noise</span>‚Äù applied</p>
  91.               </div>
  92.             </div>
  93.           </div>
  94.         </div>
  95.         <br class="figure-break" />
  96.         <p>
  97.       You can find this filter through
  98.       <span class="guimenu">Filters</span> ‚Üí <span class="guisubmenu">Noise</span> ‚Üí <span class="guimenuitem"><span class="accel">R</span>GB Noise</span>.
  99.     </p>
  100.         <p>
  101.       The RGB Noise filter adds a normally distributed noise to a layer or a
  102.       selection. It uses the RGB color model to produce the noise (noise is
  103.       added to red, green and blue values of each pixel). A normal
  104.       distribution means, that only slight noise is added to the most pixels
  105.       in the affected area, while less pixels are affected by more extreme
  106.       values. (If you apply this filter to an image filled with a solid grey
  107.       color and then look at its histogram, you will see a classic bell-shaped
  108.       Gaussian curve.)
  109.     </p>
  110.         <p>
  111.       The result is very naturally looking noise.
  112.     </p>
  113.         <p>
  114.       This filter does not work with indexed images.
  115.     </p>
  116.       </div>
  117.       <div class="sect3" lang="en" xml:lang="en">
  118.         <div class="titlepage">
  119.           <div>
  120.             <div>
  121.               <h4 class="title"><a id="id2733529"></a>3.3.2.¬†
  122.       <span lang="en" xml:lang="en">Options</span>
  123.     </h4>
  124.             </div>
  125.           </div>
  126.         </div>
  127.         <div class="figure">
  128.           <a id="id2733540"></a>
  129.           <p class="title">
  130.             <b>Figure¬†16.22.¬†
  131.         <span lang="en" xml:lang="en">
  132.           ‚Äú<span class="quote">RGB Noise</span>‚Äù filter options
  133.         </span>
  134.       </b>
  135.           </p>
  136.           <div class="figure-contents">
  137.             <div class="mediaobject">
  138.               <img src="../images/filters/options-noise-rgb.png" alt="RGB Noise filter options" />
  139.             </div>
  140.           </div>
  141.         </div>
  142.         <br class="figure-break" />
  143.         <div class="variablelist">
  144.           <dl>
  145.             <dt>
  146.               <span class="term">Preview</span>
  147.             </dt>
  148.             <dd>
  149.               <p>
  150.             This preview displays interactively changes before they are
  151.             applied to the image.
  152.           </p>
  153.             </dd>
  154.             <dt>
  155.               <span class="term">Correlated noise</span>
  156.             </dt>
  157.             <dd>
  158.               <p>
  159.             Noise may be additive (uncorrelated) or multiplicative (correlated
  160.             - also known as speckle noise). When checked, every channel value
  161.             is multiplied by an normally distributed value. So the noise
  162.             depends on the channel values: a greater channel value leads to
  163.             more noise, while dark colors (small values) tend to remain dark.
  164.           </p>
  165.             </dd>
  166.             <dt>
  167.               <span class="term">Independent RGB</span>
  168.             </dt>
  169.             <dd>
  170.               <p>
  171.             When this radio button is checked, you can move each RGB slider
  172.             separately.  Otherwise, sliders R, G and B will be moved all
  173.             together. The same relative noise will then be added to all
  174.             channels in each pixel, so the hue of pixels does not change much.
  175.           </p>
  176.             </dd>
  177.             <dt>
  178.               <span class="term">Red, Blue, Green and Alfa Sliders</span>
  179.             </dt>
  180.             <dd>
  181.               <p>
  182.             These slidebars and adjacent input boxes allow to set noise level
  183.             (0.00 - 1.00) in each channel. Alpha channel is only present, if
  184.             your layer holds such a channel. In case of a grayscale image, a
  185.             <span class="guilabel">Grey</span>
  186.             is shown instead of color sliders.
  187.           </p>
  188.               <p>
  189.             The value set by these sliders actually determine the standard
  190.             deviation of the normal distribution of applied noise. The used
  191.             standard deviation is a half of the set value (where 1 is the
  192.             distance between the lowest and highest possible value in a
  193.             channel).
  194.           </p>
  195.             </dd>
  196.           </dl>
  197.         </div>
  198.       </div>
  199.     </div>
  200.     <div class="navfooter">
  201.       <hr />
  202.       <table width="100%" summary="Navigation footer">
  203.         <tr>
  204.           <td width="40%" align="left"><a accesskey="p" href="plug-in-randomize-hurl.html"><img src="../images/prev.png" alt="Prev" /></a>¬†</td>
  205.           <td width="20%" align="center">
  206.             <a accesskey="u" href="filters-noise.html">
  207.               <img src="../images/up.png" alt="Up" />
  208.             </a>
  209.           </td>
  210.           <td width="40%" align="right">¬†<a accesskey="n" href="plug-in-randomize-pick.html"><img src="../images/next.png" alt="Next" /></a></td>
  211.         </tr>
  212.         <tr>
  213.           <td width="40%" align="left" valign="top"><a accesskey="p" href="plug-in-randomize-hurl.html">3.2.¬†
  214.     <span lang="en" xml:lang="en">Hurl</span>
  215.   </a>¬†</td>
  216.           <td width="20%" align="center">
  217.             <a accesskey="h" href="index.html">
  218.               <img src="../images/home.png" alt="Home" />
  219.             </a>
  220.           </td>
  221.           <td width="40%" align="right" valign="top">¬†<a accesskey="n" href="plug-in-randomize-pick.html">3.4.¬†
  222.     <span lang="en" xml:lang="en">Pick</span>
  223.   </a></td>
  224.         </tr>
  225.       </table>
  226.     </div>
  227.   </body>
  228. </html>
  229.