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<title>ImageMagick: MagickCore, C API for ImageMagick: Shear or Rotate an Image by an Arbitrary Angle</title>
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<p class="navigation-index">[ <a href="#AffineTransformImage">AffineTransformImage</a> | <a href="#RotateImage">RotateImage</a> | <a href="#ShearImage">ShearImage</a> ]</p>
<div style="margin: auto;">
<h2><a href="http://magick.imagemagick.org/viewvc/bin/cgi/viewvc.cgi/svn/ImageMagick/trunk/magick/shear.c
?view=markup" target="source" name="AffineTransformImage">AffineTransformImage</a></h2>
</div>
<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>
<p>The format of the AffineTransformImage method is:</p>
<pre class="code">
Image *AffineTransformImage(const Image *image,
AffineMatrix *affine_matrix,ExceptionInfo *exception)
</pre>
<p>A description of each parameter follows:</p></ol>
<h5>image</h5>
<ol><p>the image.</p></ol>
<h5>affine_matrix</h5>
<ol><p>the affine matrix.</p></ol>
<h5>exception</h5>
<ol><p>Return any errors or warnings in this structure.</p></ol>
<div style="margin: auto;">
<h2><a href="http://magick.imagemagick.org/viewvc/bin/cgi/viewvc.cgi/svn/ImageMagick/trunk/magick/shear.c
?view=markup" target="source" name="RotateImage">RotateImage</a></h2>
</div>
<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>
<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>
<p>The format of the RotateImage method is:</p>
<pre class="code">
Image *RotateImage(const Image *image,const double degrees,
ExceptionInfo *exception)
</pre>
<p>A description of each parameter follows.</p></ol>
<h5>image</h5>
<ol><p>the image.</p></ol>
<h5>degrees</h5>
<ol><p>Specifies the number of degrees to rotate the image.</p></ol>
<h5>exception</h5>
<ol><p>Return any errors or warnings in this structure.</p></ol>
<div style="margin: auto;">
<h2><a href="http://magick.imagemagick.org/viewvc/bin/cgi/viewvc.cgi/svn/ImageMagick/trunk/magick/shear.c
?view=markup" target="source" name="ShearImage">ShearImage</a></h2>
</div>
<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>
<p>ShearImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth.</p></ol>
<p>The format of the ShearImage method is:</p>
<pre class="code">
Image *ShearImage(const Image *image,const double x_shear,
const double y_shear,ExceptionInfo *exception)
</pre>
<p>A description of each parameter follows.</p></ol>
<h5>image</h5>
<ol><p>the image.</p></ol>
<h5>x_shear, y_shear</h5>
<ol><p>Specifies the number of degrees to shear the image.</p></ol>
<h5>exception</h5>
<ol><p>Return any errors or warnings in this structure.</p></ol>
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