Geometric operations change the spatial relationships between the objects or pixels in an image. This may be accomplished by simply moving the pixels closer together or farther apart, or by more complicated planar repositioning of the samples. Common geometric operations include translation, zooming (scaling), rotation, and warping. Zooming changes the dimensions of the image. Zooming operations may be used to enlarge a region-of-interest in an image (interpolation) or conversely to decrease the image size to improve processing speeds (decimation). Interpolation, decimation, and related sampling operations are discussed in Section 4.2. Rotation and warping are typically used to correct for imaging system distortion or, alternatively, to purposely distort an image to achieve some desired visual effect (Section
4.3). Finally, a number of useful matrix manipulation functions for edge padding, concatenation, and threading are presented in Section
4.4.