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authorMichales Michaloudes <korgie@gmail.com>2010-12-24 10:12:58 -0200
committerNiels Horn <niels.horn@slackbuilds.org>2010-12-24 10:12:58 -0200
commit2a68848278acaea9189d72fab32ebcf06a065a3d (patch)
tree536df30424890db2efbeb7c526acee4a365db1a0 /graphics/gimp-wideangle-plugin/wideangle.html
parent5d20d6632040e3c74ff336361057b1d43bdb417d (diff)
downloadslackbuilds-2a68848278acaea9189d72fab32ebcf06a065a3d.tar.gz
graphics/gimp-wideangle-plugin: Added (distortion filter for gimp)
Signed-off-by: Niels Horn <niels.horn@slackbuilds.org>
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+<html><head><title>Gimp Wideangle Filter</title></head>
+<body>
+<h1>Gimp Wideangle Filter</h1>
+<p>The Wideangle plugin is licensed under the GPL.<br/>
+The source code is available <a href="wideangle.c">here</a>. Latest version is
+1.0.10.<br/>
+<b>gimptool --install wideangle.c</b> will compile the plugin and install
+it in your local Gimp plugins directory.<br/>
+The plugin appears in the <b>Filters/Distorts</b> menu as
+<b>Wideangle...</b>.</p>
+<p>The Wideangle filter is used to correct (or simulate) the distortion
+typically seen on photographs taken with a wideangle lens. There are six
+controls.
+<dl>
+<dt>X Shift</dt>
+<dd>Adjusts the centre of the effect, from the left edge of the image (at -100.0),
+through the centre (at 0.0), to the right edge (at 100.0).</dd>
+<dt>Y Shift</dt>
+<dd>Adjusts the centre of the effect, from the top edge of the image (at -100.0),
+through the centre (at 0.0), to the bottom edge (at 100.0).</dd>
+<dt>Main</dt>
+<dd>Controls the amount of distortion. Negative values correct wideangle (barrel)
+distortion, while positive values create it (or correct pincushion distortion).</dd>
+<dt>Edge</dt>
+<dd>Like the <b>Main</b> control, but the <b>Edge</b> control has more effect
+at the edges of the image than at the centre.</dd>
+<dt>Zoom</dt>
+<dd>Zooms the entire image in or out.</dd>
+<dt>Brighten</dt>
+<dd>Adjusts the image brightness up or down with distance from the centre.
+Can be used to remove (or create) vignetting, the darkening of the corners
+of an image.</dd>
+</dl>
+</p>
+
+<p>The <b>Do Preview</b> toggle enables and disables the preview window.
+The preview can show either an overview of the whole image, or a detail view
+which shows a 5x5 array of full resolution closeups. The overview is useful for
+casual use, while the detail view
+allows you to create a precisely calibrated preset for a particular lens. To create
+a lens preset, use
+a photo of a grid pattern. Start by adjusting the <b>Main</b> control until the
+lines of the grid are as straight as possible. Use the <b>Shift</b> controls, if
+necessary, to correct for any asymmetry. Finally, if the best setting of the
+<b>Main</b> control leaves a &quot;wiggle&quot; in the lines, use the <b>Edge</b>
+control to remove it. (You may need to readjust the <b>Main</b> control a little.)
+Once you have the correct settings for a particular lens, you should be able
+to save the settings as a new preset and use them for all images taken with that
+lens.</p>
+
+<p>Or just play around.</p>
+
+<p>The preset controls allow you to reset everything, select a previously defined
+preset, or save the current settings (if they've been altered) under a new name.
+Preset names can contain (fairly) arbitrary characters. If you mess up the presets,
+they are stored in a text file under your Gimp user
+directory in the <code>wideangle</code> subdirectory.</p>
+
+<p>Regardless of the Gimp's settings, the Wideangle filter always uses cubic
+interpolation. This is not a bug, it's a feature.</p>
+
+<p><b>What's with the pop up menu on the &quot;select&quot; button?</b></p>
+
+<p>I originally had a regular option menu to select presets. However this had
+a drawback, namely that the displayed option was only correct until a control
+was adjusted. A pop up menu, although not the normal choice, provides exactly
+the correct model to the user.</p>
+
+<p>Written by David Hodson. Many thanks for suggestions and improvements
+to Lars Clausen. (But bugs are still my fault.)</p>
+
+</body></html>