
The implementation of a geometric operation requires two separate algo-
rithms. One is the algorithm that defines the spatial transformation itself, that is,
a(x, y) and b(x, y). This specifies the ‘‘motion’’ as each pixel ‘‘moves’’ from its
original position in the input image to its final position in the output image. The
pixels in a digital image reside on a rectangular grid with integer coordinates, but
the spatial transformation generates noninteger pixel locations. Recall from
Chapter 1 that the continuous image, an analytic function that corresponds to
the digital image, can be generated by interpolation. This problem, then, is
solved by a gray-level ...