1 2 3 4 5 <!DOCTYPE html> 6 <html lang="en"> 7 <head> 8 <title>ImageMagick: MagickCore, C API for ImageMagick: Shear or Rotate an Image by an Arbitrary Angle</title> 9 <meta charset="utf-8" /> 10 <meta http-equiv="X-UA-Compatible" content="IE=edge" /> 11 <meta name="viewport" content="width=device-width, initial-scale=1" /> 12 <meta http-equiv="content-type" content="text/html; charset=utf-8"/> 13 <meta name="application-name" content="ImageMagick"/> 14 <meta name="description" content="ImageMagick is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 200) including PNG, JPEG, JPEG-2000, GIF, WebP, Postscript, PDF, and SVG. 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Paeth, Graphics Interface '86 (Vancouver). ShearRotateImage() is adapted from a similar method based on the Paeth paper written by Michael Halle of the Spatial Imaging Group, MIT Media Lab.</p> 64 65 <h2><a href="http://www.imagemagick.org/api/MagickCore/shear_8c.html" id="DeskewImage">DeskewImage</a></h2> 66 67 <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> 68 69 <p>The result will be auto-croped if the artifact "deskew:auto-crop" is defined, while the amount the image is to be deskewed, in degrees is also saved as the artifact "deskew:angle".</p> 70 71 <p>If the artifact "deskew:auto-crop" is given the image will be automatically cropped of the excess background. The value is the border width of all pixels around the edge that will be used to determine an average border color for the automatic trim.</p> 72 73 <p>The format of the DeskewImage method is:</p> 74 75 <pre class="text"> 76 Image *DeskewImage(const Image *image,const double threshold, 77 ExceptionInfo *exception) 78 </pre> 79 80 <p>A description of each parameter follows:</p> 81 82 <dd> 83 </dd> 84 85 <dd> </dd> 86 <dl class="dl-horizontal"> 87 <dt>image</dt> 88 <dd>the image. </dd> 89 90 <dd> </dd> 91 <dt>threshold</dt> 92 <dd>separate background from foreground. </dd> 93 94 <dd> </dd> 95 <dt>exception</dt> 96 <dd>return any errors or warnings in this structure. </dd> 97 98 <dd> </dd> 99 </dl> 100 <h2><a href="http://www.imagemagick.org/api/MagickCore/shear_8c.html" id="IntegralRotateImage">IntegralRotateImage</a></h2> 101 102 <p>IntegralRotateImage() rotates the image an integral of 90 degrees. It allocates the memory necessary for the new Image structure and returns a pointer to the rotated image.</p> 103 104 <p>The format of the IntegralRotateImage method is:</p> 105 106 <pre class="text"> 107 Image *IntegralRotateImage(const Image *image,size_t rotations, 108 ExceptionInfo *exception) 109 </pre> 110 111 <p>A description of each parameter follows.</p> 112 113 <dt>image</dt> 114 <p>the image.</p> 115 116 <dt>rotations</dt> 117 <p>Specifies the number of 90 degree rotations.</p> 118 119 <h2><a href="http://www.imagemagick.org/api/MagickCore/shear_8c.html" id="ShearImage">ShearImage</a></h2> 120 121 <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> 122 123 <p>ShearImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth.</p> 124 125 <p>The format of the ShearImage method is:</p> 126 127 <pre class="text"> 128 Image *ShearImage(const Image *image,const double x_shear, 129 const double y_shear,ExceptionInfo *exception) 130 </pre> 131 132 <p>A description of each parameter follows.</p> 133 134 <dt>image</dt> 135 <p>the image.</p> 136 137 <dt>x_shear, y_shear</dt> 138 <p>Specifies the number of degrees to shear the image.</p> 139 140 <dt>exception</dt> 141 <p>return any errors or warnings in this structure.</p> 142 143 <h2><a href="http://www.imagemagick.org/api/MagickCore/shear_8c.html" id="ShearRotateImage">ShearRotateImage</a></h2> 144 145 <p>ShearRotateImage() 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. ShearRotateImage allocates the memory necessary for the new Image structure and returns a pointer to the new image.</p> 146 147 <p>ShearRotateImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth. ShearRotateImage is adapted from a similar method based on the Paeth paper written by Michael Halle of the Spatial Imaging Group, MIT Media Lab.</p> 148 149 <p>The format of the ShearRotateImage method is:</p> 150 151 <pre class="text"> 152 Image *ShearRotateImage(const Image *image,const double degrees, 153 ExceptionInfo *exception) 154 </pre> 155 156 <p>A description of each parameter follows.</p> 157 158 <dt>image</dt> 159 <p>the image.</p> 160 161 <dt>degrees</dt> 162 <p>Specifies the number of degrees to rotate the image.</p> 163 164 <dt>exception</dt> 165 <p>return any errors or warnings in this structure.</p> 166 167 </div> 168 <footer class="magick-footer"> 169 <p><a href="../support.html">Donate</a> 170 <a href="../sitemap.html">Sitemap</a> 171 <a href="../links.html">Related</a> 172 <a href="../architecture.html">Architecture</a> 173 </p> 174 <p><a href="shear.html#">Back to top</a> 175 <a href="http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x89AB63D48277377A">Public Key</a> 176 <a href="http://www.imagemagick.org/script/contact.php">Contact Us</a></p> 177 <p><small> 1999-2016 ImageMagick Studio LLC</small></p> 178 </footer> 179 </div><!-- /.container --> 180 181 <script src="https://localhost/ajax/libs/jquery/1.11.3/jquery.min.js"></script> 182 <script src="../js/magick.html"></script> 183 </div> 184 </body> 185 </html> 186
