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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 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>

<p>The format of the AffineTransformImage method is:</p>

<pre class="code">
  Image *AffineTransformImage(const Image *image,AffineMatrix *affine,
    ExceptionInfo *exception)
</pre>

<p>A description of each parameter follows:</p>

<h4>image</h4>
<p>The image.</p>

<h4>affine</h4>
<p>The affine transform.</p>

<h4>exception</h4>
<p>Return any errors or warnings in this structure.</p>

<div style="margin: auto;">
  <h2><a 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>

<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>

<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>

<h4>image</h4>
<p>The image.</p>

<h4>degrees</h4>
<p>Specifies the number of degrees to rotate the image.</p>

<h4>exception</h4>
<p>Return any errors or warnings in this structure.</p>

<div style="margin: auto;">
  <h2><a 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>

<p>ShearImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth.</p>

<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>

<h4>image</h4>
<p>The image.</p>

<h4>x_shear, y_shear</h4>
<p>Specifies the number of degrees to shear the image.</p>

<h4>exception</h4>
<p>Return any errors or warnings in this structure.</p>

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