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cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]11 <link rel="shortcut icon" href="../../images/wand.ico" type="images/vnd.microsoft.icon"/>
12 <title>ImageMagick: MagickCore, C API for ImageMagick: Shear or Rotate an Image by an Arbitrary Angle</title>
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151</div>
cristy3eaa0ef2010-03-06 20:35:26 +0000[diff] [blame]152
153
154</div>
155
156<div class="main">
157
cristy3ed852e2009-09-05 21:47:34 +0000[diff] [blame]158<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>
159
160<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
161_8c.html" target="source" name="AffineTransformImage">AffineTransformImage</a></h2>
162<div class="doc-section">
163
164<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>
165
166<p>The format of the AffineTransformImage method is:</p>
167
168<pre class="code">
169 Image *AffineTransformImage(const Image *image,
170 AffineMatrix *affine_matrix,ExceptionInfo *exception)
171</pre>
172
173<p>A description of each parameter follows:</p></ol>
174
175<h5>image</h5>
176<ol><p>the image.</p></ol>
177
178<h5>affine_matrix</h5>
179<ol><p>the affine matrix.</p></ol>
180
181<h5>exception</h5>
182<ol><p>return any errors or warnings in this structure.</p></ol>
183
184 </div>
185<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
186_8c.html" target="source" name="DeskewImage">DeskewImage</a></h2>
187<div class="doc-section">
188
189<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>
190
191<p>The format of the DeskewImage method is:</p>
192
193<pre class="code">
194 Image *DeskewImage(const Image *image,const double threshold,
195 ExceptionInfo *exception)
196</pre>
197
198<p>A description of each parameter follows:</p></ol>
199
200<h5>image</h5>
201<ol><p>the image.</p></ol>
202
203<h5>threshold</h5>
204<ol><p>separate background from foreground.</p></ol>
205
206<h5>exception</h5>
207<ol><p>return any errors or warnings in this structure.</p></ol>
208
209 </div>
210<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
211_8c.html" target="source" name="RotateImage">RotateImage</a></h2>
212<div class="doc-section">
213
214<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>
215
216<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>
217
218<p>The format of the RotateImage method is:</p>
219
220<pre class="code">
221 Image *RotateImage(const Image *image,const double degrees,
222 ExceptionInfo *exception)
223</pre>
224
225<p>A description of each parameter follows.</p></ol>
226
227<h5>image</h5>
228<ol><p>the image.</p></ol>
229
230<h5>degrees</h5>
231<ol><p>Specifies the number of degrees to rotate the image.</p></ol>
232
233<h5>exception</h5>
234<ol><p>return any errors or warnings in this structure.</p></ol>
235
236 </div>
237<h2><a href="http://www.imagemagick.org/api/MagickCore/shear
238_8c.html" target="source" name="ShearImage">ShearImage</a></h2>
239<div class="doc-section">
240
241<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>
242
243<p>ShearImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth.</p></ol>
244
245<p>The format of the ShearImage method is:</p>
246
247<pre class="code">
248 Image *ShearImage(const Image *image,const double x_shear,
249 const double y_shear,ExceptionInfo *exception)
250</pre>
251
252<p>A description of each parameter follows.</p></ol>
253
254<h5>image</h5>
255<ol><p>the image.</p></ol>
256
257<h5>x_shear, y_shear</h5>
258<ol><p>Specifies the number of degrees to shear the image.</p></ol>
259
260<h5>exception</h5>
261<ol><p>return any errors or warnings in this structure.</p></ol>
262
263 </div>
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