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<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>3.13.  Convolve (Blur/Sharpen)</title> <link rel="stylesheet" href="gimp-help-plain.css" type="text/css" /> <link rel="stylesheet" href="gimp-help-screen.css" type="text/css" /> <link rel="stylesheet" href="gimp-help-custom.css" type="text/css" /> <link rel="alternate stylesheet" href="gimp22.css" type="text/css" title="gimp22" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="GNU Image Manipulation Program" /> <link rel="up" href="gimp-tools-paint.html" title="3.  Brush Tools" /> <link rel="prev" href="gimp-tool-perspective-clone.html" title="3.12.  Perspective Clone" /> <link rel="next" href="gimp-tool-smudge.html" title="3.14.  Smudge" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">3.13.  <span lang="en" xml:lang="en">Convolve (Blur/Sharpen)</span> </th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="gimp-tool-perspective-clone.html"><img src="../images/prev.png" alt="Prev" /></a> </td> <th width="60%" align="center">3.  <span lang="en" xml:lang="en">Brush Tools</span> </th> <td width="20%" align="right"> <a accesskey="n" href="gimp-tool-smudge.html"><img src="../images/next.png" alt="Next" /></a></td> </tr> </table> <hr /> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="gimp-tool-convolve"></a>3.13.  <span lang="en" xml:lang="en">Convolve (Blur/Sharpen)</span> </h3> </div> <div> <div class="revhistory"> <table border="1" width="100%" summary="Revision history"> <tr> <th align="left" valign="top" colspan="3"> <b>Revision History</b> </th> </tr> <tr> <td align="left">Revision $Revision: 2422 $</td> <td align="left">2008-02-27</td> <td align="left">j.h</td> </tr> </table> </div> </div> </div> </div> <a id="id2635910" class="indexterm"></a> <a id="id2635923" class="indexterm"></a> <div class="figure"> <a id="id2635932"></a> <p class="title"> <b>Figure 13.78.  <span lang="en" xml:lang="en">Convolve tool icon in the Toolbox</span> </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img src="../images/toolbox/toolbox-blur.png" alt="Convolve tool icon in the Toolbox" /> </div> </div> </div> <br class="figure-break" /> <p> The Convolve tool uses the current brush to locally blur or sharpen your image. Blurring with it can be useful if some element of your image stands out too much, and you would like to soften it. If you want to blur a whole layer, or a large part of one, you will probably be better off using one of the <a class="link" href="filters-blur.html" title="2.  Blur Filters">Blur Filters</a>. The direction of a brushstroke has no effect: if you want directional blurring, use the Smudge tool. </p> <p> In “<span class="quote">Sharpen</span>” mode, the tool works by increasing the contrast where the brush is applied. A little bit of this may be useful, but over-application will produce noise. Some of the <a class="link" href="filters-enhance.html" title="5.  Enhance Filters">Enhancement Filters</a>, particularly the <a class="link" href="plug-in-unsharp-mask.html" title="5.7.  Unsharp Mask">Unsharp Mask</a>, do a much cleaner job of sharpening areas of a layer. </p> <div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;"> <table border="0" summary="Tip"> <tr> <td rowspan="2" align="center" valign="top" width="25"> <img alt="[Tip]" src="../images/tip.png" /> </td> <th align="left">Tip</th> </tr> <tr> <td align="left" valign="top"> <p> You can create a more sophisticated sharpening brush using the Clone tool. To do this, start by duplicating the layer you want to work on, and run a sharpening filter, such as Unsharp Mask, on the copy. Then activate the Clone tool, and in its Tool Options set Source to “<span class="quote">Image source</span>” and Alignment to “<span class="quote">Registered</span>”. Set the Opacity to a modest value, such as 10. Then Ctrl-click on the copy to make it the source image. If you now paint on the original layer, you will mix together, where the brush is applied, the sharpened version with the unsharpened version. </p> </td> </tr> </table> </div> <p> Both blurring and sharpening work incrementally: moving the brush repeatedly over an area will increase the effect with each additional pass. The Rate control allows you to determine how quickly the modifications accumulate. The Opacity control, however, can be used to limit the amount of blurring that can be produced by a single brushstroke, regardless of how many passes are made with it. </p> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id2636052"></a>3.13.1.  <span lang="en" xml:lang="en">How to Activate</span> </h4> </div> </div> </div> <p> The Convolve tool can be activated from an image menu as <span class="guimenu">Tools</span> → <span class="guisubmenu">Paint Tools</span> → <span class="guimenuitem">Convolve</span>; from the Toolbox by clicking on the tool icon <span class="guiicon"> <span class="inlinemediaobject"><img src="../images/toolbox/stock-tool-blur-22.png" /></span> </span>; or from the keyboard using the shortcut <span class="keycap"><strong>Shift </strong></span>+<span class="keycap"><strong>U</strong></span>. </p> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id2636126"></a>3.13.2.  <span lang="en" xml:lang="en">Key modifiers</span> </h4> </div> </div> </div> <p> See the <a class="link" href="gimp-tools-paint.html#gimp-tool-brush" title="3.1.  Common Features">Brush Tools Overview</a> for a description of key modifiers that have the same effect on all brush tools. </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <span class="keycap"><strong>Ctrl</strong></span>: Holding down the Ctrl key toggles between Blur and Sharpen modes; it reverses the setting shown in the Tool Options. </p> </li> </ul> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="id2636173"></a>3.13.3.  <span lang="en" xml:lang="en">Tool Options</span> </h4> </div> </div> </div> <div class="figure"> <a id="id2636183"></a> <p class="title"> <b>Figure 13.79.  <span lang="en" xml:lang="en">Tool Options for the Convolve tool</span> </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img src="../images/toolbox/tool-options-convolve.png" alt="Tool Options for the Convolve tool" /> </div> </div> </div> <br class="figure-break" /> <div class="variablelist"> <dl> <dt> <span class="term"> Opacity; Brush; Scale; Pressure Sensitivity; Fade Out; Hard Edges </span> </dt> <dd> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <table border="0" summary="Note"> <tr> <td rowspan="2" align="center" valign="top" width="25"> <img alt="[Note]" src="../images/note.png" /> </td> <th align="left">Note</th> </tr> <tr> <td align="left" valign="top"> <p> See the <a class="link" href="gimp-tools-paint.html#gimp-tool-brush-options" title="3.1.2.  Tool Options">Brush Tools Overview</a> for a description of tool options that apply to many or all brush tools. </p> </td> </tr> </table> </div> </dd> <dt> <span class="term">Convolve Type</span> </dt> <dd> <p> <span class="emphasis"><em>Blur</em></span> mode causes each pixel affected by the brush to be blended with neighboring pixels, thereby increasing the similarity of pixels inside the brushstroke area. <span class="emphasis"><em>Sharpen</em></span> mode causes each pixel to become more different from its neighbors than it previously was: it increases contrast inside the brushstroke area. Too much Sharpen ends in an ugly flocculation aspect. Whatever setting you choose here, you can reverse it on-the-fly by holding down the Ctrl key. </p> <p> “<span class="quote">Convolve</span>” refers to a mathematical method using matrices. </p> </dd> <dt> <span class="term">Rate</span> </dt> <dd> <p> The <span class="guilabel">Rate</span> slider sets the strength of the convolve effect. </p> </dd> </dl> </div> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="gimp-tool-perspective-clone.html"><img src="../images/prev.png" alt="Prev" /></a> </td> <td width="20%" align="center"> <a accesskey="u" href="gimp-tools-paint.html"> <img src="../images/up.png" alt="Up" /> </a> </td> <td width="40%" align="right"> <a accesskey="n" href="gimp-tool-smudge.html"><img src="../images/next.png" alt="Next" /></a></td> </tr> <tr> <td width="40%" align="left" valign="top"><a accesskey="p" href="gimp-tool-perspective-clone.html">3.12.  <span lang="en" xml:lang="en">Perspective Clone</span> </a> </td> <td width="20%" align="center"> <a accesskey="h" href="index.html"> <img src="../images/home.png" alt="Home" /> </a> </td> <td width="40%" align="right" valign="top"> <a accesskey="n" href="gimp-tool-smudge.html">3.14.  <span lang="en" xml:lang="en">Smudge</span> </a></td> </tr> </table> </div> </body> </html> 
