Scale - change image content size
Rotate - change image content orientation
Reflect - flip over image contents
Translate - change image content position
Affine Transformation - general image content linear geometric transformation
A geometric operation maps pixel information (i.e. the intensity values at each pixel location ) in an input image to another location in an output image. For basic operators described in this package, these functions are first order polynomials which take the form:
Translation can be accomplished by specifying values for the B matrix, while scaling, rotation and reflection are defined by instantiating variables in the A matrix. A general affine transformation (which uses both matrices) can be used to perform a combination of these operations at once, and is often used in applications, e.g. remote sensing, where we wish to correct for geometric distortions in the image introduced by perspective irregularities. Geometric operators are also used to improve the visualization of the image, e.g. zooming an interesting region of the image, or as a part of an image processing chain where, e.g. translation is required in order to register two images.
©2003 R. Fisher, S. Perkins,
A. Walker and E. Wolfart.