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  6.     <title>5.6.┬áLevels tool</title>
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  13.     <link rel="next" href="ch03s05s07.html" title="5.7.┬áCurves Tool" />
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  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="ch03s05s05.html">Prev</a>┬á</td>
  23.           <th width="60%" align="center" id="sectionname">5.6.┬áLevels tool</th>
  24.           <td width="20%" align="right">┬á<a accesskey="n" href="ch03s05s07.html">Next</a></td>
  25.         </tr>
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  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-levels"></a>5.6.┬áLevels tool</h3>
  34.           </div>
  35.         </div>
  36.       </div>
  37.       <div class="mediaobject">
  38.         <img src="../images/toolbox/tools-levels.png" />
  39.       </div>
  40.       <p>                  
  41.     The Level tool provides features similar to the Histogram tool but can 
  42.     also change the intensity range of the active layer or selection.
  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="id3443714"></a>Activate Tool</h4>
  49.             </div>
  50.           </div>
  51.         </div>
  52.         <p>
  53.       The Level 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">L</span>evels
  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="id3443755"></a>Options</h4>
  66.             </div>
  67.           </div>
  68.         </div>
  69.         <div class="variablelist">
  70.           <dl>
  71.             <dt>
  72.               <span class="term">Modify Levels for Channel</span>
  73.             </dt>
  74.             <dd>
  75.               <p>
  76.           You can select the specific channel which will be modified by the
  77.           tool: Value makes changes to the luminosity of all pixels in the
  78.           image. Color channels allow to change saturation. Alpha channel
  79.           works on transparency.  <span class="guilabel">Initialize channel</span>
  80.           cancels changes to the selected channel.
  81.         </p>
  82.             </dd>
  83.             <dt>
  84.               <span class="term">Input Levels</span>
  85.             </dt>
  86.             <dd>
  87.               <p>
  88.           The main area is a graphic representation of image dark, mid and
  89.           light tones content. They are on abscissa from level 0 (black) to
  90.           level 255 (white). Pixel number for a level is on ordinate axis.
  91.           The curve surface represents all the pixels of the image for the
  92.           selected channel. A well balanced image is an image with levels
  93.           (tones) distributed all over the whole range. An image with a
  94.           blue predominant color, for example, will produce a histogram
  95.           shifted to the left in Green and Red channels, signified by green
  96.           and red lacking on highlights.
  97.         </p>
  98.               <p>
  99.           Level ranges can be modified in three ways:
  100.         </p>
  101.               <div class="itemizedlist">
  102.                 <ul type="opencircle">
  103.                   <li style="list-style-type: circle">
  104.                     <p>
  105.                Three triangles as sliders: one black for dark tones, one grey 
  106.                for midtones (often called Gamma value), one white for light
  107.                tones.
  108.              </p>
  109.                   </li>
  110.                   <li style="list-style-type: circle">
  111.                     <p>               
  112.                Three eyedroppers: use the left one to pick the darkest
  113.                color, the mid one to pick the mid tone color, the right one
  114.                to pick the lightest color on the image. You can use 
  115.                View/Info Window to find these colors. 
  116.              </p>
  117.                   </li>
  118.                   <li style="list-style-type: circle">
  119.                     <p>
  120.                Three input boxes to enter values directly.
  121.              </p>
  122.                   </li>
  123.                 </ul>
  124.               </div>
  125.             </dd>
  126.             <dt>
  127.               <span class="term">Output Levels</span>
  128.             </dt>
  129.             <dd>
  130.               <p>
  131.           Output Levels allows manual selection of a constrained output level 
  132.           range. There are also arrow-heads located here that can be used to
  133.           interactively change the Output Levels.
  134.         </p>
  135.             </dd>
  136.             <dt>
  137.               <span class="term">All Channels</span>
  138.             </dt>
  139.             <dd>
  140.               <p>
  141.             <span class="guilabel">Load</span>: This button allows you to select a file 
  142.             holding level settings.
  143.           </p>
  144.               <p>
  145.             <span class="guilabel">Save</span>: Allows you to save any levels you have set 
  146.             to a file that can be loaded later.
  147.           </p>
  148.               <p>
  149.             <span class="guilabel">Auto</span>: Performs an automatic setting of the 
  150.             levels.
  151.           </p>
  152.               <p>
  153.             <span class="guilabel">Three eyedroppers</span>: These three
  154.             controls determine three points on the grayscale.  Any
  155.             level below the "Black Point" is black; any point above
  156.             the "White Point" is white.  The "Gray Point", which must
  157.             be between the other two, determines the middle level of
  158.             Gray.  All shades of gray are calculated from these three
  159.             levels.
  160.           </p>
  161.             </dd>
  162.             <dt>
  163.               <span class="term">Preview</span>
  164.             </dt>
  165.             <dd>
  166.               <p>
  167.            The Preview button makes all changes to the levels dynamically so 
  168.            that the new level settings can be viewed straight away.
  169.          </p>
  170.             </dd>
  171.           </dl>
  172.         </div>
  173.       </div>
  174.     </div>
  175.     <div class="navfooter">
  176.       <hr />
  177.       <table width="100%" summary="Navigation footer">
  178.         <tr>
  179.           <td width="40%" align="left"><a accesskey="p" href="ch03s05s05.html">Prev</a>┬á</td>
  180.           <td width="20%" align="center">
  181.             <a accesskey="u" href="ch03s05.html">Up</a>
  182.           </td>
  183.           <td width="40%" align="right">┬á<a accesskey="n" href="ch03s05s07.html">Next</a></td>
  184.         </tr>
  185.         <tr>
  186.           <td width="40%" align="left" valign="top">5.5.┬áThreshold Tool┬á</td>
  187.           <td width="20%" align="center">
  188.             <a accesskey="h" href="index.html">Home</a>
  189.           </td>
  190.           <td width="40%" align="right" valign="top">┬á5.7.┬áCurves Tool</td>
  191.         </tr>
  192.       </table>
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  196.