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12 <title>ImageMagick: MagickCore, C API for ImageMagick: Shear or Rotate an Image by an Arbitrary Angle</title>
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150
151</div>
152
153<div class="main">
154
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]155<p class="navigation-index">[<a href="#AffineTransformImage">AffineTransformImage</a> &bull; <a href="#DeskewImage">DeskewImage</a> &bull; <a href="#RotateImage">RotateImage</a> &bull; <a href="#ShearImage">ShearImage</a>]</p>
156
157<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
158_8c.html" target="source" name="AffineTransformImage">AffineTransformImage</a></h2>
159<div class="doc-section">
160
161<p>AffineTransformImage() transforms an image as dictated by the affine matrix. It allocates the memory necessary for the new Image structure and returns a pointer to the new image.</p></ol>
162
163<p>The format of the AffineTransformImage method is:</p>
164
165<pre class="code">
166 Image *AffineTransformImage(const Image *image,
167 AffineMatrix *affine_matrix,ExceptionInfo *exception)
168</pre>
169
170<p>A description of each parameter follows:</p></ol>
171
172<h5>image</h5>
173<ol><p>the image.</p></ol>
174
175<h5>affine_matrix</h5>
176<ol><p>the affine matrix.</p></ol>
177
178<h5>exception</h5>
179<ol><p>return any errors or warnings in this structure.</p></ol>
180
181 </div>
182<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
183_8c.html" target="source" name="DeskewImage">DeskewImage</a></h2>
184<div class="doc-section">
185
186<p>DeskewImage() removes skew from the image. Skew is an artifact that occurs in scanned images because of the camera being misaligned, imperfections in the scanning or surface, or simply because the paper was not placed completely flat when scanned.</p></ol>
187
188<p>The format of the DeskewImage method is:</p>
189
190<pre class="code">
191 Image *DeskewImage(const Image *image,const double threshold,
192 ExceptionInfo *exception)
193</pre>
194
195<p>A description of each parameter follows:</p></ol>
196
197<h5>image</h5>
198<ol><p>the image.</p></ol>
199
200<h5>threshold</h5>
201<ol><p>separate background from foreground.</p></ol>
202
203<h5>exception</h5>
204<ol><p>return any errors or warnings in this structure.</p></ol>
205
206 </div>
207<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
208_8c.html" target="source" name="RotateImage">RotateImage</a></h2>
209<div class="doc-section">
210
211<p>RotateImage() creates a new image that is a rotated copy of an existing one. Positive angles rotate counter-clockwise (right-hand rule), while negative angles rotate clockwise. Rotated images are usually larger than the originals and have 'empty' triangular corners. X axis. Empty triangles left over from shearing the image are filled with the background color defined by member 'background_color' of the image. RotateImage allocates the memory necessary for the new Image structure and returns a pointer to the new image.</p></ol>
212
213<p>RotateImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth. RotateImage is adapted from a similar method based on the Paeth paper written by Michael Halle of the Spatial Imaging Group, MIT Media Lab.</p></ol>
214
215<p>The format of the RotateImage method is:</p>
216
217<pre class="code">
218 Image *RotateImage(const Image *image,const double degrees,
219 ExceptionInfo *exception)
220</pre>
221
222<p>A description of each parameter follows.</p></ol>
223
224<h5>image</h5>
225<ol><p>the image.</p></ol>
226
227<h5>degrees</h5>
228<ol><p>Specifies the number of degrees to rotate the image.</p></ol>
229
230<h5>exception</h5>
231<ol><p>return any errors or warnings in this structure.</p></ol>
232
233 </div>
234<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
235_8c.html" target="source" name="ShearImage">ShearImage</a></h2>
236<div class="doc-section">
237
238<p>ShearImage() creates a new image that is a shear_image copy of an existing one. Shearing slides one edge of an image along the X or Y axis, creating a parallelogram. An X direction shear slides an edge along the X axis, while a Y direction shear slides an edge along the Y axis. The amount of the shear is controlled by a shear angle. For X direction shears, x_shear is measured relative to the Y axis, and similarly, for Y direction shears y_shear is measured relative to the X axis. Empty triangles left over from shearing the image are filled with the background color defined by member 'background_color' of the image.. ShearImage() allocates the memory necessary for the new Image structure and returns a pointer to the new image.</p></ol>
239
240<p>ShearImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth.</p></ol>
241
242<p>The format of the ShearImage method is:</p>
243
244<pre class="code">
245 Image *ShearImage(const Image *image,const double x_shear,
246 const double y_shear,ExceptionInfo *exception)
247</pre>
248
249<p>A description of each parameter follows.</p></ol>
250
251<h5>image</h5>
252<ol><p>the image.</p></ol>
253
254<h5>x_shear, y_shear</h5>
255<ol><p>Specifies the number of degrees to shear the image.</p></ol>
256
257<h5>exception</h5>
258<ol><p>return any errors or warnings in this structure.</p></ol>
259
260 </div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]261
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