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  4.   <head>
  5.     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  6.     <title>2.2.¬† Channels Dialog</title>
  7.     <link rel="stylesheet" href="gimp-help-plain.css" type="text/css" />
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  12.     <link rel="start" href="index.html" title="GNU Image Manipulation Program" />
  13.     <link rel="up" href="gimp-dialogs-structure.html" title="2.¬† Image Structure Related Dialogs" />
  14.     <link rel="prev" href="gimp-dialogs-structure.html" title="2.¬† Image Structure Related Dialogs" />
  15.     <link rel="next" href="gimp-path-dialog.html" title="2.3.¬† Path Dialog" />
  16.   </head>
  17.   <body>
  18.     <div class="navheader">
  19.       <table width="100%" summary="Navigation header">
  20.         <tr>
  21.           <th colspan="3" align="center">2.2.¬†
  22.     <span lang="en" xml:lang="en">Channels Dialog</span>
  23.   </th>
  24.         </tr>
  25.         <tr>
  26.           <td width="20%" align="left"><a accesskey="p" href="gimp-dialogs-structure.html"><img src="../images/prev.png" alt="Prev" /></a>¬†</td>
  27.           <th width="60%" align="center">2.¬†
  28.     <span lang="en" xml:lang="en">Image Structure Related Dialogs</span>
  29.   </th>
  30.           <td width="20%" align="right">¬†<a accesskey="n" href="gimp-path-dialog.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="gimp-channel-dialog"></a>2.2.¬†
  40.     <span lang="en" xml:lang="en">Channels Dialog</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: 2405 $</td>
  53.                   <td align="left">2007-08-29</td>
  54.                   <td align="left">j.h</td>
  55.                 </tr>
  56.               </table>
  57.             </div>
  58.           </div>
  59.         </div>
  60.       </div>
  61.       <a id="id2654288" class="indexterm"></a>
  62.       <a id="id2654301" class="indexterm"></a>
  63.       <div class="figure">
  64.         <a id="id2654316"></a>
  65.         <p class="title">
  66.           <b>Figure¬†14.7.¬†
  67.       <span lang="en" xml:lang="en">The Channel dialog</span>
  68.     </b>
  69.         </p>
  70.         <div class="figure-contents">
  71.           <div class="mediaobject">
  72.             <img src="../images/dialogs/dialogs-channel.png" alt="The Channel dialog" />
  73.           </div>
  74.         </div>
  75.       </div>
  76.       <br class="figure-break" />
  77.       <p>
  78.     The Channels dialog is the main interface to edit, modify and manage your
  79.     channels. Channels have a double usage. This is why the dialog is divided
  80.     into two parts: the first part for color channels and the second part for
  81.     selection masks.
  82.   </p>
  83.       <p>
  84.     Color channels: Color channels apply to the image and not to a specific
  85.     layer. Basically, three primary colors are necessary to render all the
  86.     wide range of natural colors. As other digital software, the GIMP
  87.     uses Red, Green, and Blue as primary colors. The first and primary
  88.     channels display the <span class="guilabel">Red</span>, <span class="guilabel">Green</span>,
  89.     and <span class="guilabel">Blue</span>
  90.     values of each pixel in your image. In front of each channel is a
  91.     thumbnail displaying a grayscale representation of each channel, where
  92.     white is 100% and black is 0% of the primary color. Alternatively, if your
  93.     image is not a colored but a Grayscale image, there is only one primary
  94.     channel called <span class="guilabel">Gray</span>.
  95.     For an Indexed image with a fixed number of known colors there is also
  96.     only one primary channel called <span class="guilabel">Indexed</span>.
  97.     Then there is a optional channel called <span class="guilabel">Alpha</span>.
  98.     This channel displays transparency values of each pixel in your image
  99.     (See <a class="link" href="glossary.html#glossary-alpha-channel" title="Alpha Channel">Alpha Channel</a> in
  100.     Glossary). In front of this channel is a thumbnail displaying a grayscale
  101.     representation of the transparency where white is opaque and visible, and
  102.     black is transparent and invisible. If you create your image without
  103.     transparency then the Alpha channel is not present, but you can add it
  104.     from the <a class="link" href="gimp-dialogs-structure.html#gimp-layer-dialog" title="2.1.¬† Layers Dialog">Layers dialog menu</a>.
  105.     Also, if you have more than one layer in your image, GIMP automatically
  106.     creates an Alpha channel.
  107.   </p>
  108.       <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
  109.         <table border="0" summary="Note">
  110.           <tr>
  111.             <td rowspan="2" align="center" valign="top" width="25">
  112.               <img alt="[Note]" src="../images/note.png" />
  113.             </td>
  114.             <th align="left">Note</th>
  115.           </tr>
  116.           <tr>
  117.             <td align="left" valign="top">
  118.               <p>GIMP doesn't support CMYK or YUV color models.</p>
  119.             </td>
  120.           </tr>
  121.         </table>
  122.       </div>
  123.       <div class="figure">
  124.         <a id="id2654443"></a>
  125.         <p class="title">
  126.           <b>Figure¬†14.8.¬†
  127.       <span lang="en" xml:lang="en">Representation of an image with channels</span>
  128.     </b>
  129.         </p>
  130.         <div class="figure-contents">
  131.           <div class="mediaobject">
  132.             <img src="../images/dialogs/wilber-channels-red.png" alt="Representation of an image with channels" />
  133.             <div class="caption">
  134.               <p>Red channel</p>
  135.             </div>
  136.           </div>
  137.           <div class="mediaobject">
  138.             <img src="../images/dialogs/wilber-channels-green.png" alt="Representation of an image with channels" />
  139.             <div class="caption">
  140.               <p>Green channel</p>
  141.             </div>
  142.           </div>
  143.           <div class="mediaobject">
  144.             <img src="../images/dialogs/wilber-channels-blue.png" alt="Representation of an image with channels" />
  145.             <div class="caption">
  146.               <p>Blue channel</p>
  147.             </div>
  148.           </div>
  149.           <div class="mediaobject">
  150.             <img src="../images/dialogs/wilber-channels-alpha.png" alt="Representation of an image with channels" />
  151.             <div class="caption">
  152.               <p>Alpha channel</p>
  153.             </div>
  154.           </div>
  155.           <div class="mediaobject">
  156.             <img src="../images/dialogs/wilber-channels-combined.png" alt="Representation of an image with channels" />
  157.             <div class="caption">
  158.               <p>All Channels</p>
  159.             </div>
  160.           </div>
  161.         </div>
  162.       </div>
  163.       <br class="figure-break" />
  164.       <p>
  165.     The right image is decomposed in three color channels (red, green, and
  166.     blue) and the Alpha channel for transparency. On the right image the
  167.     transparency is displayed as a gray checkerboard. In the color channel
  168.     white is always white because all the colors are present and black is
  169.     black. The red hat is visible in the red channel but quite invisible in
  170.     the other channels. This is the same for plain green and blue which are
  171.     visible only in their own channels and invisible in others.
  172.   </p>
  173.       <div class="sect3" lang="en" xml:lang="en">
  174.         <div class="titlepage">
  175.           <div>
  176.             <div>
  177.               <h4 class="title"><a id="gimp-channel-dialog-calling"></a>2.2.1.¬†
  178.       <span lang="en" xml:lang="en">Calling the Dialog</span>
  179.     </h4>
  180.             </div>
  181.           </div>
  182.         </div>
  183.         <p>The Channel dialog can be activated in many ways :</p>
  184.         <div class="itemizedlist">
  185.           <ul type="disc">
  186.             <li>
  187.               <p>
  188.           from the toolbox-menu:
  189.           <span class="guimenu">File</span> ‚Üí <span class="guisubmenu">Dialogs</span> ‚Üí <span class="guimenuitem">Channels</span>
  190.         </p>
  191.             </li>
  192.             <li>
  193.               <p>
  194.           from the image-menu:
  195.           <span class="guimenu">Dialogs</span> ‚Üí <span class="guimenuitem">Channels</span>
  196.         </p>
  197.             </li>
  198.             <li>
  199.               <p>
  200.           from another dialog-menu:
  201.           <span class="guimenu">Add Tab</span> ‚Üí <span class="guimenuitem">Channels</span>
  202.         </p>
  203.             </li>
  204.           </ul>
  205.         </div>
  206.       </div>
  207.       <div class="sect3" lang="en" xml:lang="en">
  208.         <div class="titlepage">
  209.           <div>
  210.             <div>
  211.               <h4 class="title"><a id="gimp-channel-dialog-using"></a>2.2.2.¬†
  212.       <span lang="en" xml:lang="en">Using the Channel dialog</span>
  213.     </h4>
  214.             </div>
  215.           </div>
  216.         </div>
  217.         <div class="sect4" lang="en" xml:lang="en">
  218.           <div class="titlepage">
  219.             <div>
  220.               <div>
  221.                 <h5 class="title"><a id="gimp-channel-dialog-using-overview"></a>2.2.2.1.¬†
  222.         <span lang="en" xml:lang="en">Overview</span>
  223.       </h5>
  224.               </div>
  225.             </div>
  226.           </div>
  227.           <p>
  228.         The top channels are the color channels and the optional Alpha
  229.         channel. They are always organized in the same order and they cannot
  230.         be erased. Selection masks are described below and displayed as a list
  231.         in the dialog. Every channel appears in the list in form of a
  232.         thumbnail. A right-click in a channel thumbnail opens the
  233.         <a class="link" href="gimp-channel-dialog.html#gimp-channel-menu" title="2.2.2.4.¬† Channels Context Menu">channel menu</a>.
  234.       </p>
  235.         </div>
  236.         <div class="sect4" lang="en" xml:lang="en">
  237.           <div class="titlepage">
  238.             <div>
  239.               <div>
  240.                 <h5 class="title"><a id="gimp-channel-dialog-using-attributes"></a>2.2.2.2.¬†
  241.         <span lang="en" xml:lang="en">Channel attributes</span>
  242.       </h5>
  243.               </div>
  244.             </div>
  245.           </div>
  246.           <p>
  247.         Every channel is shown in the list with its own attributes. These
  248.         attributes are very similar to the ones described in
  249.         <a class="xref" href="gimp-dialogs-structure.html#gimp-layer-dialog" title="2.1.¬† Layers Dialog">Section¬†2.1, ‚Äú
  250.     <span lang="en" xml:lang="en">Layers Dialog</span>
  251.   ‚Äù</a> for the layer dialog.
  252.       </p>
  253.           <div class="caution" style="margin-left: 0.5in; margin-right: 0.5in;">
  254.             <table border="0" summary="Caution">
  255.               <tr>
  256.                 <td rowspan="2" align="center" valign="top" width="25">
  257.                   <img alt="[Caution]" src="../images/caution.png" />
  258.                 </td>
  259.                 <th align="left">Caution</th>
  260.               </tr>
  261.               <tr>
  262.                 <td align="left" valign="top">
  263.                   <p>
  264.           Activated channels appear highlighted (generally) in blue in the
  265.           dialog. If you click on a channel in the list you toggle activation
  266.           of the corresponding channel. Disabling a color channel red, blue,
  267.           or green has severe consequences. For instance if you disable the
  268.           blue channel, all pixels from now on added to the image will not
  269.           have blue component, and so a white pixel will have the yellow
  270.           complementary color.
  271.         </p>
  272.                 </td>
  273.               </tr>
  274.             </table>
  275.           </div>
  276.         </div>
  277.         <div class="sect4" lang="en" xml:lang="en">
  278.           <div class="titlepage">
  279.             <div>
  280.               <div>
  281.                 <h5 class="title"><a id="gimp-channel-dialog-using-managing"></a>2.2.2.3.¬†
  282.         <span lang="en" xml:lang="en">Managing channels</span>
  283.       </h5>
  284.               </div>
  285.             </div>
  286.           </div>
  287.           <a id="id2654810" class="indexterm"></a>
  288.           <a id="id2654824" class="indexterm"></a>
  289.           <a id="id2654839" class="indexterm"></a>
  290.           <a id="id2654852" class="indexterm"></a>
  291.           <a id="id2654866" class="indexterm"></a>
  292.           <a id="id2654879" class="indexterm"></a>
  293.           <p>
  294.         Under the channel list is a set of buttons allowing you to perform
  295.         some basic operations on channel list.
  296.       </p>
  297.           <div class="variablelist">
  298.             <dl>
  299.               <dt>
  300.                 <a id="gimp-channel-edit"></a>
  301.                 <span class="term">
  302.             <span class="guiicon">
  303.               <span class="inlinemediaobject"><img src="../images/dialogs/stock-edit-16.png" /></span>
  304.             </span>
  305.             <span lang="en" xml:lang="en">Edit channel attributes,</span>
  306.           </span>
  307.               </dt>
  308.               <dd>
  309.                 <p>
  310.               only available for selection masks. Here you can change the
  311.               <span class="guilabel">Channel name</span>. The other two parameters
  312.               affect channel is visibility in the image window; they control
  313.               <span class="guilabel">Opacity</span> and color used for the mask in the
  314.               image window. A click on the color button displays the GIMP
  315.               color selector and then you can change the mask color.
  316.             </p>
  317.               </dd>
  318.               <dt>
  319.                 <a id="gimp-channel-new"></a>
  320.                 <span class="term">
  321.             <span class="guiicon">
  322.               <span class="inlinemediaobject"><img src="../images/dialogs/dialogs-icon-new.png" /></span>
  323.             </span>
  324.             <span lang="en" xml:lang="en">New channel</span>
  325.           </span>
  326.               </dt>
  327.               <dd>
  328.                 <p> 
  329.               You can create here a new channel. The displayed dialog lets
  330.               you set <span class="guilabel">Opacity</span> and mask color used in
  331.               the image to represent the selection. (If you use the
  332.               <span class="guibutton">New Channel</span> button in Channel Menu,
  333.               you can create this new channel with the options previously
  334.               used by pressing the <span class="keycap"><strong>Shift</strong></span> key when clicking).
  335.               This new channel is a channel mask (a selection mask) applied
  336.               over the image. See
  337.               <a class="link" href="gimp-channel-dialog.html#dialogs-selection-masks" title="2.2.3.¬† Selection masks">Selection Mask</a>
  338.             </p>
  339.               </dd>
  340.               <dt>
  341.                 <span class="term">
  342.             <a id="gimp-channel-raise"></a>
  343.             <span class="guiicon">
  344.               <span class="inlinemediaobject"><img src="../images/dialogs/dialogs-icon-raise.png" /></span>
  345.             </span>
  346.             <span lang="en" xml:lang="en">Raise channel,</span>
  347.           </span>
  348.               </dt>
  349.               <dd>
  350.                 <p>
  351.               only available for selection masks : you can here put the
  352.               channel up a level in the list. Press <span class="keycap"><strong>Shift</strong></span>
  353.               key to move channel to top of the list.
  354.             </p>
  355.               </dd>
  356.               <dt>
  357.                 <span class="term">
  358.             <a id="gimp-channel-lower"></a>
  359.             <span class="guiicon">
  360.               <span class="inlinemediaobject"><img src="../images/dialogs/dialogs-icon-lower.png" /></span>
  361.             </span>
  362.             <span lang="en" xml:lang="en">Lower channel</span>
  363.           </span>
  364.               </dt>
  365.               <dd>
  366.                 <p>
  367.               You can here put the channel down a level in the list. Press the
  368.               <span class="keycap"><strong>Shift</strong></span> key to move the channel to bottom of the
  369.               list.
  370.             </p>
  371.               </dd>
  372.               <dt>
  373.                 <span class="term">
  374.             <a id="gimp-channel-duplicate"></a>
  375.             <span class="guiicon">
  376.               <span class="inlinemediaobject"><img src="../images/dialogs/stock-duplicate-16.png" /></span>
  377.             </span>
  378.             <span lang="en" xml:lang="en">Duplicate channel</span>
  379.           </span>
  380.               </dt>
  381.               <dd>
  382.                 <p>
  383.               You can create here a copy of the active channel. Name of new
  384.               channel is suffixed with a number.
  385.             </p>
  386.                 <div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;">
  387.                   <table border="0" summary="Tip">
  388.                     <tr>
  389.                       <td rowspan="2" align="center" valign="top" width="25">
  390.                         <img alt="[Tip]" src="../images/tip.png" />
  391.                       </td>
  392.                       <th align="left">Tip</th>
  393.                     </tr>
  394.                     <tr>
  395.                       <td align="left" valign="top">
  396.                         <p>
  397.                 You can also duplicate a color channel or the Alpha channel.
  398.                 It's an easy way to keep a copy of them and to use them later
  399.                 as a selection in an image.
  400.               </p>
  401.                       </td>
  402.                     </tr>
  403.                   </table>
  404.                 </div>
  405.               </dd>
  406.               <dt>
  407.                 <span class="term">
  408.             <a id="gimp-channel-selection-replace"></a>
  409.             <span class="guiicon">
  410.               <span class="inlinemediaobject"><img src="../images/dialogs/stock-selection-16.png" /></span>
  411.             </span>
  412.             <span lang="en" xml:lang="en">Channel to selection</span>
  413.           </span>
  414.               </dt>
  415.               <dd>
  416.                 <p>
  417.               here you can transform the channel to become a selection. By
  418.               default the selection derived from a channel replaces any
  419.               previous active selection. It's possible to change this by
  420.               clicking on control keys.
  421.             </p>
  422.                 <div class="itemizedlist">
  423.                   <ul type="disc">
  424.                     <li>
  425.                       <p><a id="gimp-channel-selection-add"></a>
  426.                   <span class="keycap"><strong>Shift</strong></span>:
  427.                   the selection derived from a channel is added to the
  428.                   previous active selection. The final selection is merged
  429.                   from both.
  430.                 </p>
  431.                     </li>
  432.                     <li>
  433.                       <p><a id="gimp-channel-selection-subtract"></a>
  434.                   <span class="keycap"><strong>Ctrl</strong></span>:
  435.                   the final selection is the subtraction of selection derived
  436.                   from a channel from the previously active one.
  437.                 </p>
  438.                     </li>
  439.                     <li>
  440.                       <p><a id="gimp-channel-selection-intersect"></a>
  441.                   <span class="keycap"><strong>Shift</strong></span>+<span class="keycap"><strong>Ctrl</strong></span>:
  442.                   the final selection is the intersection of selection derived
  443.                   from a channel with the previously active one. Only common
  444.                   parts are kept.
  445.                 </p>
  446.                     </li>
  447.                   </ul>
  448.                 </div>
  449.               </dd>
  450.               <dt>
  451.                 <span class="term">
  452.             <a id="gimp-channel-selection-delete"></a>
  453.             <span class="guiicon">
  454.               <span class="inlinemediaobject"><img src="../images/dialogs/dialogs-icon-delete.png" /></span>
  455.             </span>
  456.             <span lang="en" xml:lang="en">Delete channel</span>
  457.           </span>
  458.               </dt>
  459.               <dd>
  460.                 <p>
  461.               only available for selection masks: you can here delete the
  462.               active channel.
  463.             </p>
  464.               </dd>
  465.             </dl>
  466.           </div>
  467.         </div>
  468.         <div class="sect4" lang="en" xml:lang="en">
  469.           <div class="titlepage">
  470.             <div>
  471.               <div>
  472.                 <h5 class="title"><a id="gimp-channel-menu"></a>2.2.2.4.¬†
  473.     <span lang="en" xml:lang="en">Channels Context Menu</span>
  474.   </h5>
  475.               </div>
  476.               <div>
  477.                 <div class="revhistory">
  478.                   <table border="1" width="100%" summary="Revision history">
  479.                     <tr>
  480.                       <th align="left" valign="top" colspan="3">
  481.                         <b>Revision History</b>
  482.                       </th>
  483.                     </tr>
  484.                     <tr>
  485.                       <td align="left">Revision $Revision: 2347 $</td>
  486.                       <td align="left">2006-02-27</td>
  487.                       <td align="left">j.h</td>
  488.                     </tr>
  489.                   </table>
  490.                 </div>
  491.               </div>
  492.             </div>
  493.           </div>
  494.           <a id="id2655433" class="indexterm"></a>
  495.           <div class="figure">
  496.             <a id="id2655447"></a>
  497.             <p class="title">
  498.               <b>Figure¬†14.9.¬†
  499.       <span lang="en" xml:lang="en">Channels Menu</span>
  500.     </b>
  501.             </p>
  502.             <div class="figure-contents">
  503.               <div class="mediaobject">
  504.                 <img src="../images/dialogs/dialogs-channel-menu.png" alt="Channels Menu" />
  505.               </div>
  506.             </div>
  507.           </div>
  508.           <br class="figure-break" />
  509.           <div class="variablelist">
  510.             <dl>
  511.               <dt>
  512.                 <span class="term">Overview</span>
  513.               </dt>
  514.               <dd>
  515.                 <p>
  516.           You can get the channel context menu by right clicking on a channel
  517.           thumbnail. This menu gives the same operations on channels as those
  518.           available from dialog buttons. The only difference concerns
  519.           transformation to selection operations, each of them having its own
  520.           entry in the menu.
  521.         </p>
  522.                 <div class="itemizedlist">
  523.                   <ul type="disc">
  524.                     <li>
  525.                       <p>
  526.               <span class="guilabel">Edit channel attributes</span>,
  527.               <span class="guilabel">New channel</span>,
  528.               <span class="guilabel">Raise channel</span>,
  529.               <span class="guilabel">Lower channel</span>,
  530.               <span class="guilabel">Duplicate channel</span>,
  531.               <span class="guilabel">Delete channel</span>: see
  532.               <a class="link" href="gimp-channel-dialog.html#gimp-channel-edit">Managing channels</a>.
  533.             </p>
  534.                     </li>
  535.                     <li>
  536.                       <p>
  537.               <span class="guilabel">Channel to selection</span>:
  538.               Selection derived from channel replaces any previous active
  539.               selection.
  540.             </p>
  541.                     </li>
  542.                     <li>
  543.                       <p>
  544.               <span class="guilabel">Add to selection</span>:
  545.               Selection derived from channel is added to previous active
  546.               selection. Final selection is merging of both.
  547.             </p>
  548.                     </li>
  549.                     <li>
  550.                       <p>
  551.               <span class="guilabel">Substract from selection</span>:
  552.               Final selection is substraction of selection derived from a
  553.               channel from previous active selection.
  554.             </p>
  555.                     </li>
  556.                     <li>
  557.                       <p>
  558.               <span class="guilabel">Intersect with selection</span>:
  559.               Final selection is intersection of selection derived from a
  560.               channel with the previous active selection. Only common parts
  561.               are kept.
  562.             </p>
  563.                     </li>
  564.                   </ul>
  565.                 </div>
  566.               </dd>
  567.             </dl>
  568.           </div>
  569.         </div>
  570.       </div>
  571.       <div class="sect3" lang="en" xml:lang="en">
  572.         <div class="titlepage">
  573.           <div>
  574.             <div>
  575.               <h4 class="title"><a id="dialogs-selection-masks"></a>2.2.3.¬†
  576.     <span lang="en" xml:lang="en">Selection masks</span>
  577.   </h4>
  578.             </div>
  579.             <div>
  580.               <div class="revhistory">
  581.                 <table border="1" width="100%" summary="Revision history">
  582.                   <tr>
  583.                     <th align="left" valign="top" colspan="3">
  584.                       <b>Revision History</b>
  585.                     </th>
  586.                   </tr>
  587.                   <tr>
  588.                     <td align="left">Revision $Revision: 2405 $</td>
  589.                     <td align="left">2006-02-27</td>
  590.                     <td align="left">j.h</td>
  591.                   </tr>
  592.                 </table>
  593.               </div>
  594.             </div>
  595.           </div>
  596.         </div>
  597.         <a id="id2655670" class="indexterm"></a>
  598.         <a id="id2655684" class="indexterm"></a>
  599.         <a id="id2655697" class="indexterm"></a>
  600.         <a id="id2655711" class="indexterm"></a>
  601.         <a id="id2655724" class="indexterm"></a>
  602.         <div class="figure">
  603.           <a id="id2655738"></a>
  604.           <p class="title">
  605.             <b>Figure¬†14.10.¬†
  606.       <span lang="en" xml:lang="en">A selection composed out of channels.</span>
  607.     </b>
  608.           </p>
  609.           <div class="figure-contents">
  610.             <div class="mediaobject">
  611.               <img src="../images/dialogs/dialogs-channel-masks.png" alt="A selection composed out of channels." />
  612.             </div>
  613.           </div>
  614.         </div>
  615.         <br class="figure-break" />
  616.         <p>
  617.     Channels can be used to save and restore your selections. Clicking on the
  618.     <span class="guilabel">Quick mask</span> button on the
  619.     <a class="link" href="gimp-image-window.html" title="2.2.¬† Image Window">Image window</a>
  620.     automatically creates a new channel called <span class="guilabel">Qmask</span>
  621.     and saves the displayed active selection to a thumbnail in front of the
  622.     channel.There are many selection tools in GIMP like rectangular
  623.     selection tool or fuzzy selection for continuous selections. Selection
  624.     Masks are a graphical way to build selections into a gray level channel
  625.     where white pixels are selected and black pixels are not selected.
  626.     Therefore gray pixels are partially selected. You can think of them as
  627.     feathering the selection, a smooth transition between selected and not
  628.     selected. This is important to avoid the ugly pixelization effect when you
  629.     fill the selection or when you erase its content after isolating a subject
  630.     from background.
  631.   </p>
  632.         <div class="variablelist">
  633.           <dl>
  634.             <dt>
  635.               <span class="term">Creating Selection Masks</span>
  636.             </dt>
  637.             <dd>
  638.               <p>
  639.           There are several ways to initialize a selection mask.  From the
  640.           image window menu
  641.           <span class="guimenu"><span class="accel">S</span>elect</span> ‚Üí <span class="guimenuitem">Save to <span class="accel">C</span>hannel</span>
  642.           if there is an active selection.  From the image window
  643.           the bottom-left button creates a <a class="link" href="gimp-channel-dialog.html#gimp-qmask" title="2.2.4.¬† Quick Mask">Quick
  644.             Mask</a>; the content will be initialized with the active
  645.           selection.  From the channel dialog, when you click on the
  646.           <span class="guilabel">New channel</span> button or from the context menu.
  647.           When created, this Selection mask appears in the Channel dialog,
  648.           named ‚Äú<span class="quote">Selection mask copy</span>‚Äù with a queuing number.
  649.           You can change this by using the context menu that you get by
  650.           right-clicking on the channel.
  651.         </p>
  652.             </dd>
  653.           </dl>
  654.         </div>
  655.         <div class="sect4" lang="en" xml:lang="en">
  656.           <div class="titlepage">
  657.             <div>
  658.               <div>
  659.                 <h5 class="title"><a id="id2655878"></a>2.2.3.1.¬†
  660.       <span lang="en" xml:lang="en">Using Selection Masks</span>
  661.     </h5>
  662.               </div>
  663.             </div>
  664.           </div>
  665.           <p>
  666.       Once the channel is initialized, selected (highlighted in blue), visible
  667.       (eye-icon in the dialog), and displayed as you want (color and opacity
  668.       attributes), you can start to work with all the paint tools. The colors
  669.       used are important. If you paint with some color other than white, grey,
  670.       or black, the color Value (luminosity) will be used to define a gray
  671.       (medium, light, or dark). When your mask is painted, you can transform
  672.       it to a selection by clicking on the
  673.       <span class="guilabel">Channel to selection</span>
  674.       button or from the context menu.
  675.     </p>
  676.           <p>
  677.       You can work in selection masks not only with the paint tool but also
  678.       with other tools. For instance, you can use the selection tools to fill
  679.       areas uniformly with gradients or patterns. By adding many selection
  680.       masks in your list you can easily compose very complex selections. One
  681.       can say that a selection mask is to a selection as a layer is to an
  682.       image.
  683.     </p>
  684.           <div class="caution" style="margin-left: 0.5in; margin-right: 0.5in;">
  685.             <table border="0" summary="Caution">
  686.               <tr>
  687.                 <td rowspan="2" align="center" valign="top" width="25">
  688.                   <img alt="[Caution]" src="../images/caution.png" />
  689.                 </td>
  690.                 <th align="left">Caution</th>
  691.               </tr>
  692.               <tr>
  693.                 <td align="left" valign="top">
  694.                   <p>
  695.         As long as a selection mask is activated you are working in the mask
  696.         and not in the image. To work in the image you have to deactivate all
  697.         selection masks. Don't forget also to stop displaying masks in the
  698.         image by removing the eye icon. Check also that all RGB and Alpha
  699.         channels are activated and displayed in the image.
  700.       </p>
  701.                 </td>
  702.               </tr>
  703.             </table>
  704.           </div>
  705.         </div>
  706.       </div>
  707.       <div class="sect3" lang="en" xml:lang="en">
  708.         <div class="titlepage">
  709.           <div>
  710.             <div>
  711.               <h4 class="title"><a id="gimp-qmask"></a>2.2.4.¬†
  712.     <span lang="en" xml:lang="en">Quick Mask</span>
  713.   </h4>
  714.             </div>
  715.             <div>
  716.               <div class="revhistory">
  717.                 <table border="1" width="100%" summary="Revision history">
  718.                   <tr>
  719.                     <th align="left" valign="top" colspan="3">
  720.                       <b>Revision History</b>
  721.                     </th>
  722.                   </tr>
  723.                   <tr>
  724.                     <td align="left">Revision $Revision: 2419 $</td>
  725.                     <td align="left">2007-08-24</td>
  726.                     <td align="left">j.h</td>
  727.                   </tr>
  728.                 </table>
  729.               </div>
  730.             </div>
  731.           </div>
  732.         </div>
  733.         <div class="figure">
  734.           <a id="id2655982"></a>
  735.           <p class="title">
  736.             <b>Figure¬†14.11.¬†
  737.       <span lang="en" xml:lang="en">Dialog Quick Mask</span>
  738.     </b>
  739.           </p>
  740.           <div class="figure-contents">
  741.             <div class="mediaobject">
  742.               <img src="../images/dialogs/dialogs-channel-quickmask.png" alt="Dialog Quick Mask" />
  743.             </div>
  744.           </div>
  745.         </div>
  746.         <br class="figure-break" />
  747.         <p>
  748.     A <span class="guilabel">Quick Mask</span> is a
  749.     <a class="link" href="gimp-channel-dialog.html#dialogs-selection-masks" title="2.2.3.¬† Selection masks">Selection Mask</a>
  750.     intended to be used temporarily to paint a selection. Temporarily means
  751.     that, unlike a normal selection mask, it will be deleted from the
  752.     channel list after its transformation to selection. The
  753.     <a class="link" href="gimp-tools-selection.html" title="2.¬†Selection Tools">selection tools</a>
  754.     sometimes show their limits when they have to be used for doing complex
  755.     drawing selection, as progressive. In this case, using the QuickMask is a
  756.     good idea which can give very good results.
  757.   </p>
  758.         <div class="sect4" lang="en" xml:lang="en">
  759.           <div class="titlepage">
  760.             <div>
  761.               <div>
  762.                 <h5 class="title"><a id="id2656046"></a>2.2.4.1.¬†
  763.       <span lang="en" xml:lang="en">Activate dialog</span>
  764.     </h5>
  765.               </div>
  766.             </div>
  767.           </div>
  768.           <div class="itemizedlist">
  769.             <ul type="disc">
  770.               <li>
  771.                 <p>
  772.           The QuickMask can be activated in the following order, from the
  773.           image-menu: <span class="guimenuitem"><span class="accel">S</span>elect/Toggle
  774.             <span class="accel">Q</span>uickMask</span>.
  775.         </p>
  776.               </li>
  777.               <li>
  778.                 <p>
  779.           The QuickMask can also be activated by clicking the left-bottom
  780.           button showed in red on the screenshot.
  781.         </p>
  782.               </li>
  783.               <li>
  784.                 <p>
  785.           It can also be activated by using <span class="keycap"><strong>Shift+Q</strong></span>
  786.           shortcut.
  787.         </p>
  788.               </li>
  789.             </ul>
  790.           </div>
  791.         </div>
  792.         <div class="sect4" lang="en" xml:lang="en">
  793.           <div class="titlepage">
  794.             <div>
  795.               <div>
  796.                 <h5 class="title"><a id="id2656109"></a>2.2.4.2.¬†
  797.       <span lang="en" xml:lang="en">Creating a Quick Mask</span>
  798.     </h5>
  799.               </div>
  800.             </div>
  801.           </div>
  802.           <p>
  803.       To initialize a <span class="guilabel">Quick Mask</span>,
  804.       click the bottom-left button in the image window. If a selection was
  805.       active in your image, then its content appears unchanged while the
  806.       border is covered with a translucent red color. If no selection was
  807.       active then all the image is covered with a translucent red color. At
  808.       every moment you can hide the mask by clicking on the eye icon
  809.       <span class="guiicon">
  810.         <span class="inlinemediaobject"><img src="../images/dialogs/stock-eye-20.png" /></span>
  811.       </span>
  812.       in front of the <span class="guilabel">QMask</span>.
  813.       From the channel dialog you can double click on the name or the
  814.       thumbnail to edit the <span class="guilabel">QMask</span>
  815.       attributes. Then you can change the <span class="guilabel">Opacity</span>
  816.       and its filling color. Once a quick mask is initialized click on it to
  817.       be sure it is selected and blue highlighted in the list, and start to
  818.       paint on it with any GIMP paint tool. The mask is coded in gray tones,
  819.       so you must use white or gray to decrease the area limited by the mask
  820.       and black to increase it. The area painted in light or dark gray will
  821.       be transition areas for the selection like feathering. When your mask
  822.       is ready, click again on the bottom-left button in the image window and
  823.       the quick mask will be removed from the channel list and converted to
  824.       a selection. Quick mask's purpose is to paint a selection and its
  825.       transitions with the paint tools without worrying about managing
  826.       selection masks. It's a good way to isolate a subject in a picture
  827.       because once the selection is made you only have to remove its content
  828.       (or inverse if the subject is in the selection).
  829.     </p>
  830.         </div>
  831.         <div class="sect4" lang="en" xml:lang="en">
  832.           <div class="titlepage">
  833.             <div>
  834.               <div>
  835.                 <h5 class="title"><a id="id2656192"></a>2.2.4.3.¬†
  836.       <span lang="en" xml:lang="en">Using Quick Mask's</span>
  837.     </h5>
  838.               </div>
  839.             </div>
  840.           </div>
  841.           <div class="mediaobject">
  842.             <img src="../images/dialogs/dialogs-channel-masks-gradient.png" />
  843.           </div>
  844.           <div class="orderedlist">
  845.             <p class="title">
  846.               <b>
  847.         <span lang="en" xml:lang="en">Description</span>
  848.       </b>
  849.             </p>
  850.             <ol type="1">
  851.               <li>
  852.                 <p>
  853.           Screenshot of the image window with activated QuickMask. The
  854.           QuickMask is filled with a gradient from black (left) to white
  855.           (right).
  856.         </p>
  857.               </li>
  858.               <li>
  859.                 <p>
  860.           The QuickMask is now disabled and a selection is initialised from
  861.           the QuickMask, which was filled by a gradient before. You see the
  862.           selection borders in the middle of the image.
  863.         </p>
  864.               </li>
  865.               <li>
  866.                 <p>
  867.           A stroke is now added during the enabled selection. The key is,
  868.           that the black color will have no opacity of the resulting stroke
  869.           (right) and white color will have a full opacity of the stroke
  870.           (left).
  871.         </p>
  872.               </li>
  873.             </ol>
  874.           </div>
  875.           <p>
  876.       After the QuickMask Button is pressed, the command generates a
  877.       temporary 8-bit (0-255) channel, on which the progressive selection
  878.       work is stored. If a selection is already present the mask is
  879.       initialized with the content of the selection. Once QuickMask has been
  880.       activated, the image is covered by a red semi-transparent veil. This
  881.       one represents the non-selected pixels. Any
  882.       <a class="link" href="gimp-tools-paint.html" title="3.¬† Brush Tools">paint tool</a>
  883.       can be used to create the selection on the QuickMask. They should use
  884.       only greyscale color, conforming the channel properties, white enabling
  885.       to define the future selected place. The selection will be displayed as
  886.       soon as the QuickMask will be toggled but its temporary channel will
  887.       not be available anymore.
  888.     </p>
  889.           <div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;">
  890.             <table border="0" summary="Tip">
  891.               <tr>
  892.                 <td rowspan="2" align="center" valign="top" width="25">
  893.                   <img alt="[Tip]" src="../images/tip.png" />
  894.                 </td>
  895.                 <th align="left">Tip</th>
  896.               </tr>
  897.               <tr>
  898.                 <td align="left" valign="top">
  899.                   <p>
  900.         To save in a channel the selection done with the Quickmask select in
  901.         the image menu
  902.         <span class="guimenuitem">Select/Save to Channel</span>
  903.       </p>
  904.                 </td>
  905.               </tr>
  906.             </table>
  907.           </div>
  908.         </div>
  909.         <div class="sect4" lang="en" xml:lang="en">
  910.           <div class="titlepage">
  911.             <div>
  912.               <div>
  913.                 <h5 class="title"><a id="id2656322"></a>2.2.4.4.¬†
  914.       <span lang="en" xml:lang="en">Usage</span>
  915.     </h5>
  916.               </div>
  917.             </div>
  918.           </div>
  919.           <div class="procedure">
  920.             <ol type="1">
  921.               <li>
  922.                 <p>
  923.           <a class="link" href="gimp-file-open.html" title="5.3.¬† Open">Open</a> an image or begin a
  924.           <a class="link" href="gimp-file-new.html" title="5.2.¬† New">new document</a>.
  925.         </p>
  926.               </li>
  927.               <li>
  928.                 <p>
  929.           Activate the Quickmask using the left-bottom button in the image
  930.           window. If a selection is present the mask is initialized with the
  931.           content of the selection.
  932.         </p>
  933.               </li>
  934.               <li>
  935.                 <p>
  936.           Choose a <a class="link" href="gimp-tools-paint.html" title="3.¬† Brush Tools">drawing tool</a>
  937.           and use it with greyscale colors on the QuickMask.
  938.         </p>
  939.               </li>
  940.               <li>
  941.                 <p>
  942.           Deactivate the Quickmask using the left-bottom button in the image
  943.           window.
  944.         </p>
  945.               </li>
  946.             </ol>
  947.           </div>
  948.         </div>
  949.       </div>
  950.     </div>
  951.     <div class="navfooter">
  952.       <hr />
  953.       <table width="100%" summary="Navigation footer">
  954.         <tr>
  955.           <td width="40%" align="left"><a accesskey="p" href="gimp-dialogs-structure.html"><img src="../images/prev.png" alt="Prev" /></a>¬†</td>
  956.           <td width="20%" align="center">
  957.             <a accesskey="u" href="gimp-dialogs-structure.html">
  958.               <img src="../images/up.png" alt="Up" />
  959.             </a>
  960.           </td>
  961.           <td width="40%" align="right">¬†<a accesskey="n" href="gimp-path-dialog.html"><img src="../images/next.png" alt="Next" /></a></td>
  962.         </tr>
  963.         <tr>
  964.           <td width="40%" align="left" valign="top"><a accesskey="p" href="gimp-dialogs-structure.html">2.¬†
  965.     <span lang="en" xml:lang="en">Image Structure Related Dialogs</span>
  966.   </a>¬†</td>
  967.           <td width="20%" align="center">
  968.             <a accesskey="h" href="index.html">
  969.               <img src="../images/home.png" alt="Home" />
  970.             </a>
  971.           </td>
  972.           <td width="40%" align="right" valign="top">¬†<a accesskey="n" href="gimp-path-dialog.html">2.3.¬†
  973.     <span lang="en" xml:lang="en">Path Dialog</span>
  974.   </a></td>
  975.         </tr>
  976.       </table>
  977.     </div>
  978.   </body>
  979. </html>
  980.