shear - Shear or Rotate an Image by an Arbitrary Angle

NAME SYNOPSIS FUNCTION DESCRIPTIONS AffineTransformImage RotateImage ShearImage # NAME shear - Shear or Rotate an Image by an Arbitrary Angle # SYNOPSIS Image * AffineTransformImage( const Image *image, AffineMatrix *affine, ExceptionInfo *exception ); Image * RotateImage( const Image *image, const double degrees, ExceptionInfo *exception ); Image * ShearImage( const Image *image, const double x_shear, const double y_shear, ExceptionInfo *exception ); # FUNCTION DESCRIPTIONS ## AffineTransformImage 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. The format of the AffineTransformImage method is: Image *AffineTransformImage ( const Image *image, AffineMatrix *affine, ExceptionInfo *exception ); A description of each parameter follows: image: The image. affine: The affine transform. exception: Return any errors or warnings in this structure. ## RotateImage 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. 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. The format of the RotateImage method is: Image *RotateImage ( const Image *image, const double degrees, ExceptionInfo *exception ); A description of each parameter follows. image: The image. degrees: Specifies the number of degrees to rotate the image. exception: Return any errors or warnings in this structure. ## ShearImage 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. ShearImage() is based on the paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth. The format of the ShearImage method is: Image *ShearImage ( const Image *image, const double x_shear, const double y_shear, ExceptionInfo *exception ); A description of each parameter follows. image: The image. x_shear, y_shear: Specifies the number of degrees to shear the image. exception: Return any errors or warnings in this structure. "Image manipulation software that works like magick"