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  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">
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  4.   <head>
  5.     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  6.     <title>5.7.┬áCurves Tool</title>
  7.     <link rel="stylesheet" href="gimp-help-plain.css" type="text/css" />
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  10.     <link rel="start" href="index.html" title="GIMP User Manual" />
  11.     <link rel="up" href="ch03s05.html" title="5.┬áColor Tools" />
  12.     <link rel="prev" href="ch03s05s06.html" title="5.6.┬áLevels tool" />
  13.     <link rel="next" href="ch03s05s08.html" title="5.8.┬áPosterize Tool" />
  14.   </head>
  15.   <body>
  16.     <div xmlns="" class="navheader">
  17.       <table width="100%" summary="Navigation header">
  18.         <tr>
  19.           <th colspan="3" align="center" id="chaptername">5.┬áColor Tools</th>
  20.         </tr>
  21.         <tr>
  22.           <td width="20%" align="left"><a accesskey="p" href="ch03s05s06.html">Prev</a>┬á</td>
  23.           <th width="60%" align="center" id="sectionname">5.7.┬áCurves Tool</th>
  24.           <td width="20%" align="right">┬á<a accesskey="n" href="ch03s05s08.html">Next</a></td>
  25.         </tr>
  26.       </table>
  27.       <hr />
  28.     </div>
  29.     <div class="sect2" lang="en" xml:lang="en">
  30.       <div class="titlepage">
  31.         <div>
  32.           <div>
  33.             <h3 class="title"><a id="gimp-tool-curves"></a>5.7.┬áCurves Tool</h3>
  34.           </div>
  35.         </div>
  36.       </div>
  37.       <div class="mediaobject">
  38.         <img src="../images/toolbox/tools-curves.png" />
  39.       </div>
  40.       <p>
  41.     The Curves tool is the most sophisticated tool used to adjust the
  42.     tonality of images. 
  43.   </p>
  44.       <div class="simplesect" lang="en" xml:lang="en">
  45.         <div class="titlepage">
  46.           <div>
  47.             <div>
  48.               <h4 class="title"><a id="id3443986"></a>Activate Tool</h4>
  49.             </div>
  50.           </div>
  51.         </div>
  52.         <p>
  53.       The Curves Tool can be called in the following
  54.       order, from the image-menu:
  55.       <span class="guimenuitem"><span class="accel">T</span>ools</span>/
  56.       <span class="guimenuitem"><span class="accel">C</span>olor
  57.         Tools</span>/<span class="guimenuitem"><span class="accel">C</span>urves
  58.         .</span> 
  59.     </p>
  60.       </div>
  61.       <div class="simplesect" lang="en" xml:lang="en">
  62.         <div class="titlepage">
  63.           <div>
  64.             <div>
  65.               <h4 class="title"><a id="id3444027"></a>Adjust Color Curves</h4>
  66.             </div>
  67.           </div>
  68.         </div>
  69.         <div class="variablelist">
  70.           <dl>
  71.             <dt>
  72.               <span class="term">Channel</span>
  73.             </dt>
  74.             <dd>
  75.               <p>
  76.           There are five options: Value for luminosity and contrast; Red,
  77.           Green, and Blue for saturation; and Alpha.
  78.         </p>
  79.             </dd>
  80.             <dt>
  81.               <span class="term">Reset Channel</span>
  82.             </dt>
  83.             <dd>
  84.               <p>
  85.           This button deletes all changes made to the selected channel.
  86.         </p>
  87.             </dd>
  88.             <dt>
  89.               <span class="term">Linear and Logarithmic buttons</span>
  90.             </dt>
  91.             <dd>
  92.               <p>
  93.           These buttons allow to choose the Linear or Logarithmic type of 
  94.           the curve. You can also use the same options in Tool Options 
  95.           dialog. 
  96.         </p>
  97.             </dd>
  98.             <dt>
  99.               <span class="term">Main Editing Area</span>
  100.             </dt>
  101.             <dd>
  102.               <p>
  103.           <span class="guilabel">Input and Output Value Domains</span>: The
  104.           horizontal bar (x-axis) represents input values (they are value
  105.           levels from  0 to 255). The vertical bar (y-axis) is only a scale
  106.           for output colors of the selected channel.
  107.         </p>
  108.               <p>
  109.           <span class="guilabel">The control curve</span> is drawn on a grid and
  110.           goes from bottom left corner to top right corner. Pointer x/y
  111.           position is permanently displayed in top left part of the grid.
  112.           If you click on the curve, a <span class="guilabel">Control point</span>
  113.           is created. You can move it to bend the curve. If you click
  114.           outside of the curve, a control point is also created, and the
  115.           curve includes it automatically.
  116.         </p>
  117.               <p>
  118.           So, each point of the curve represents an 'x' level,
  119.           corresponding to an 'y' color. If, for example, you move a curve
  120.           segment to the right, i.e to highlights, you can see that these
  121.           highlights are corresponding to darker output tones and that
  122.           image pixels corresponding to this curve segment will go darker.
  123.           With color channels, moving right will decrease saturation ans
  124.           can reach the complementary color.
  125.         </p>
  126.               <p>
  127.           To delete all control points (apart from both ends), click on the
  128.           'Initialize Channel' button. To delete only one point, move it
  129.           onto another point or to grid border.
  130.         </p>
  131.             </dd>
  132.             <dt>
  133.               <span class="term">All Channels</span>
  134.             </dt>
  135.             <dd>
  136.               <p>
  137.           <span class="guilabel">Load</span>: This button allows you to select a file 
  138.           holding curve settings.
  139.         </p>
  140.               <p>
  141.           <span class="guilabel">Save</span>: Allows you to save any curves you have set 
  142.           to a file that can be loaded later.
  143.         </p>
  144.             </dd>
  145.             <dt>
  146.               <span class="term">Curve Type</span>
  147.             </dt>
  148.             <dd>
  149.               <p>
  150.           <span class="guilabel">Smooth</span>: This mode constrains the curve type 
  151.           to a smooth line with tension. It provides a more realistic 
  152.           render than the following.
  153.         </p>
  154.               <p>
  155.           <span class="guilabel">Free</span>: You can draw your curve free-hand with 
  156.           the mouse. With curve segments scattered all over the grid, 
  157.           result will be surprising, but poorly repeatable.
  158.         </p>
  159.             </dd>
  160.             <dt>
  161.               <span class="term">Preview</span>
  162.             </dt>
  163.             <dd>
  164.               <p>
  165.           The Preview button makes all changes to the levels dynamically so 
  166.           that the new level settings can be viewed immediately.
  167.         </p>
  168.             </dd>
  169.           </dl>
  170.         </div>
  171.         <div class="variablelist">
  172.           <p class="title">
  173.             <b>Tool Options dialog</b>
  174.           </p>
  175.           <dl>
  176.             <dt>
  177.               <span class="term">Histogram Scale</span>
  178.             </dt>
  179.             <dd>
  180.               <p>
  181.           See Linear and Logarithmic buttons in Adjust Color Curves dialog.  
  182.         </p>
  183.             </dd>
  184.             <dt>
  185.               <span class="term">Sample Average</span>
  186.             </dt>
  187.             <dd>
  188.               <p>
  189.            FIXME
  190.         </p>
  191.             </dd>
  192.           </dl>
  193.         </div>
  194.       </div>
  195.     </div>
  196.     <div class="navfooter">
  197.       <hr />
  198.       <table width="100%" summary="Navigation footer">
  199.         <tr>
  200.           <td width="40%" align="left"><a accesskey="p" href="ch03s05s06.html">Prev</a>┬á</td>
  201.           <td width="20%" align="center">
  202.             <a accesskey="u" href="ch03s05.html">Up</a>
  203.           </td>
  204.           <td width="40%" align="right">┬á<a accesskey="n" href="ch03s05s08.html">Next</a></td>
  205.         </tr>
  206.         <tr>
  207.           <td width="40%" align="left" valign="top">5.6.┬áLevels tool┬á</td>
  208.           <td width="20%" align="center">
  209.             <a accesskey="h" href="index.html">Home</a>
  210.           </td>
  211.           <td width="40%" align="right" valign="top">┬á5.8.┬áPosterize Tool</td>
  212.         </tr>
  213.       </table>
  214.     </div>
  215.   </body>
  216. </html>
  217.