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- <title>10.11.  Warp</title>
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- <th colspan="3" align="center">10.11. 
- <span lang="en" xml:lang="en">Warp</span>
- </th>
- </tr>
- <tr>
- <td width="20%" align="left"><a accesskey="p" href="plug-in-tile.html"><img src="../images/prev.png" alt="Prev" /></a> </td>
- <th width="60%" align="center">10. 
- <span lang="en" xml:lang="en">Map Filters</span>
- </th>
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- <div class="sect2" lang="en" xml:lang="en">
- <div class="titlepage">
- <div>
- <div>
- <h3 class="title"><a id="plug-in-warp"></a>10.11. 
- <span lang="en" xml:lang="en">Warp</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: 2357 $</td>
- <td align="left">2007-01-05</td>
- <td align="left">j.h</td>
- </tr>
- </table>
- </div>
- </div>
- </div>
- </div>
- <a id="id2768117" class="indexterm"></a>
- <a id="id2768135" class="indexterm"></a>
- <div class="sect3" lang="en" xml:lang="en">
- <div class="titlepage">
- <div>
- <div>
- <h4 class="title"><a id="id2768144"></a>10.11.1. 
- <span lang="en" xml:lang="en">Overview</span>
- </h4>
- </div>
- </div>
- </div>
- <p>
- You can find this filter through
- <span class="guimenu">Filters</span> ‚Üí <span class="guisubmenu">Map</span> ‚Üí <span class="guimenuitem"><span class="accel">W</span>arp</span>.
- This filter has no Preview.
- </p>
- <p>
- This filter displaces pixels of active layer or selection according to
- the grey levels of a <span class="emphasis"><em>Displacement map</em></span>. Pixels are
- displaced according to the gradient slope in the displacement map.
- Pixels corresponding to solid areas are not displaced; the higher the
- slope, the higher the displacement.
- </p>
- <div class="figure">
- <a id="id2768200"></a>
- <p class="title">
- <b>Figure 16.221. 
- <span lang="en" xml:lang="en">
- From left to right: original image, displace map, displaced image
- </span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp1.png" alt="From left to right: original image, displace map, displaced image" />
- <div class="caption">
- <p>
- Solid areas of displacement map lead to no displacement. Abrupt
- transitions give an important displacement. A linear gradient
- gives a regular displacement. Displacement direction is
- perpendicular to gradient direction (angle = 90°).
- </p>
- </div>
- </div>
- </div>
- </div>
- <br class="figure-break" />
- <div class="figure">
- <a id="id2768247"></a>
- <p class="title">
- <b>Figure 16.222. 
- <span lang="en" xml:lang="en">With a non-linear gradient</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp2.png" alt="With a non-linear gradient" />
- <div class="caption">
- <p>A non-linear gradient leads to curls.</p>
- </div>
- </div>
- </div>
- </div>
- <br class="figure-break" />
- <div class="figure">
- <a id="id2768284"></a>
- <p class="title">
- <b>Figure 16.223. 
- <span lang="en" xml:lang="en">With a complex gradient:</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp3.png" alt="With a complex gradient:" />
- <div class="caption">
- <p>
- And a complex gradient, such as the
- <a class="link" href="plug-in-solid-noise.html" title="11.3.  Solid Noise">Solid Noise</a>
- filter can create, gives a swirl effect.
- </p>
- </div>
- </div>
- </div>
- </div>
- <br class="figure-break" />
- <p>
- This filter offers the possibility of masking a part of the image to
- protect it against filter action.
- </p>
- </div>
- <div class="sect3" lang="en" xml:lang="en">
- <div class="titlepage">
- <div>
- <div>
- <h4 class="title"><a id="id2768339"></a>10.11.2. 
- <span lang="en" xml:lang="en">Options</span>
- </h4>
- </div>
- </div>
- </div>
- <div class="figure">
- <a id="id2768350"></a>
- <p class="title">
- <b>Figure 16.224. 
- <span lang="en" xml:lang="en">Warp filter options</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/options-map-warp.png" alt="Warp filter options" />
- </div>
- </div>
- </div>
- <br class="figure-break" />
- <div class="variablelist">
- <p class="title">
- <b>
- <span lang="en" xml:lang="en">Basic Options</span>
- </b>
- </p>
- <dl>
- <dt>
- <span class="term">Step Size</span>
- </dt>
- <dd>
- <p>
- “<span class="quote">Step</span>” is displacement distance for every filter
- iteration. A 10 value is necessary to get a one pixel
- displacement. This value can be negative to invert
- displacement direction.
- </p>
- </dd>
- <dt>
- <span class="term">Iterations</span>
- </dt>
- <dd>
- <p>
- <span class="guilabel">Iteration</span> is the number of repetitions of
- effect when applying filter.
- </p>
- </dd>
- <dt>
- <span class="term">On Edges</span>
- </dt>
- <dd>
- <p>
- Because of displacement, a part of pixels are driven over the
- borders of layer or selection, and, on the opposite side, pixels
- places are emptying. Four following options allow you to fix this
- issue:
- </p>
- <div class="itemizedlist">
- <ul type="disc">
- <li>
- <p>
- <span class="guilabel">Warp</span>
- (default): What goes out on one side is going into the
- opposite side.
- </p>
- </li>
- <li>
- <p>
- <span class="guilabel">Smear</span>:
- Emptying places are filled with a spreading of the
- neighbouring image line.
- </p>
- </li>
- <li>
- <p>
- <span class="guilabel">Black</span>
- : Emptying places are filled with black color.
- </p>
- </li>
- <li>
- <p>
- <span class="guilabel">FG Color</span>
- : Emptying places are filled with the Foreground color of the
- color area in Toolbox.
- </p>
- </li>
- </ul>
- </div>
- </dd>
- <dt>
- <span class="term">Displacement Map</span>
- </dt>
- <dd>
- <p>
- To be listed in this drop-down list, the displacement map,
- which is a grey-scaled image, must be <span class="emphasis"><em>present on
- your screen when you call filter and must have the same size
- as the original image</em></span>.
- </p>
- </dd>
- </dl>
- </div>
- <div class="variablelist">
- <p class="title">
- <b>
- <span lang="en" xml:lang="en">Advanced Options</span>
- </b>
- </p>
- <dl>
- <dt>
- <span class="term">Dither Size</span>
- </dt>
- <dd>
- <p>
- Once all pixels displaced, this option scatters them randomly,
- giving grain to the image. The higher this value (0.00-100.00),
- the thinner the grain.
- </p>
- <div class="figure">
- <a id="id2768583"></a>
- <p class="title">
- <b>Figure 16.225. 
- <span lang="en" xml:lang="en">With a 3.00 dither size:</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp4.png" alt="With a 3.00 dither size:" />
- </div>
- </div>
- </div>
- <br class="figure-break" />
- </dd>
- <dt>
- <span class="term">Rotation Angle</span>
- </dt>
- <dd>
- <p>
- This option sets displacement angle of pixels according to the
- slope direction of gradient. Previous examples have been created
- with a vertical gradient and a 90° angle: so, pixels were
- displaced horizontally and nothing went out of the image borders.
- Here is an example with a 10° angle and 6 iterations:
- </p>
- <div class="figure">
- <a id="id2768641"></a>
- <p class="title">
- <b>Figure 16.226. 
- <span lang="en" xml:lang="en">With a 10° angle and 6 iterations:</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp5.png" alt="With a 10° angle and 6 iterations:" />
- <div class="caption">
- <p>
- Displacement is made according to a 10° angle against
- vertical. Pixels going out the lower border on every
- iteration are going into through the upper border (Wrap
- option checked), giving a dotted line.
- </p>
- </div>
- </div>
- </div>
- </div>
- <br class="figure-break" />
- </dd>
- <dt>
- <span class="term">Magnitude map</span>
- </dt>
- <dd>
- <p>
- In addition to displacement map, you can add a
- <span class="guilabel">Magnitude Map</span>. This map is also a
- grey-scaled image, with the same size as the source image and
- which must be present on your screen when you call filter.
- This map gives more or less strength to filter on some parts
- of the image, according to the grey levels of this magnitude
- map. Image areas corresponding to white parts of this map will
- undergo all the strength of filter. Image areas corresponding
- to black parts of the map will be spared by filter.
- Intermediate grey levels will lessen filter action on
- corresponding areas of the image. <span class="guilabel">Use magnitude
- map</span> must be checked for that.
- </p>
- <div class="figure">
- <a id="id2768730"></a>
- <p class="title">
- <b>Figure 16.227. 
- <span lang="en" xml:lang="en">Magnitude Map example:</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp6.png" alt="Magnitude Map example:" />
- <div class="caption">
- <p>
- From left to right: original image, displacement map,
- magnitude map, after applying “<span class="quote">Warp</span>”
- filter. You can see that the black areas of magnitude map
- prevent filter to take action.
- </p>
- </div>
- </div>
- </div>
- </div>
- <br class="figure-break" />
- </dd>
- </dl>
- </div>
- <div class="variablelist">
- <p class="title">
- <b>
- <span lang="en" xml:lang="en">More Advanced Options</span>
- </b>
- </p>
- <p>
- These extra options let you add two new maps, a gradient map and/or
- a vector map.
- </p>
- <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>
- To test these options alone, you must use a map with a solid color
- for all the other maps.
- </p>
- </td>
- </tr>
- </table>
- </div>
- <dl>
- <dt>
- <span class="term">The Gradient Map</span>
- </dt>
- <dd>
- <p>
- <span class="emphasis"><em>The gradient map</em></span> is also a grayscaled map.
- Here, the displacement of pixels depends on the direction of
- grayscale transitions. The <span class="guilabel">Gradient scale</span>
- option lets you set how much the grayscale variations will
- influence the displacement of pixels.
- On every iteration, the filter works of the whole image, not
- only on the red object: this explains burredness.
- </p>
- <div class="figure">
- <a id="id2768839"></a>
- <p class="title">
- <b>Figure 16.228. 
- <span lang="en" xml:lang="en">Gradient map example</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp7.png" alt="Gradient map example" />
- <div class="caption">
- <p>
- From left to right: original image, displacement map,
- after applying “<span class="quote">Warp</span>” filter with a Gradient
- Scale map. Gradient is oblique, from top left to right
- bottom. The part of the image corresponding to the gradient
- is moved obliquely, 90° rotated (Rotation Angle 90° in
- Advanced options).
- </p>
- </div>
- </div>
- </div>
- </div>
- <br class="figure-break" />
- </dd>
- <dt>
- <span class="term">The Vector Map</span>
- </dt>
- <dd>
- <div class="figure">
- <a id="id2768903"></a>
- <p class="title">
- <b>Figure 16.229. 
- <span lang="en" xml:lang="en">Vector map example</span>
- </b>
- </p>
- <div class="figure-contents">
- <div class="mediaobject">
- <img src="../images/filters/examples/example-map-warp8.png" alt="Vector map example" />
- <div class="caption">
- <p>
- From left to right: original image, displacement map,
- after applying “<span class="quote">Warp</span>” filter with a Vector
- map. Gradient is vertical, from top to bottom. Vector angle
- is 45°. The image is moved obliquely, 45° to the top left
- corner. The image is blurred because every iteration works
- on the whole image, and not only on the red bar.
- </p>
- </div>
- </div>
- </div>
- </div>
- <br class="figure-break" />
- <p>
- With this map, the displacement depends on the angle you set
- in the <span class="guilabel">Angle</span> text box. 0° is upwards.
- Angles go counter-clockwise. The <span class="guilabel">Vector Magnitude
- </span> determines by how many pixels the image will move on
- every iteration.
- </p>
- </dd>
- </dl>
- </div>
- </div>
- </div>
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