ABSTRACT
A continuous two-dimensional (2-D) signal is a physical or contrived quantity that is a function of two independent variables defined over a 2-D continuous domain. The light intensity in a photograph, the depth of the ocean in a specified area, and the temperature distribution in a metal plate are examples of continuous 2-D signals. A 2-D discrete signal can be represented by a frequency spectrum that can be modified, reshaped, or manipulated through filtering, and this type of processing can be carried out by means of 2-D digital filters. The performance of a 2-D filter is usually measured in terms of the maximum ripple in the amplitude response in the passband and the minimum attenuation in the stopband. In the design of nonrecursive and recursive filters, minimax optimization methods are often preferred because their application minimizes the maximum of the approximation error. The frequency response of the 2-D filter obtained depends critically on the choice of the transformation parameters.
