ABSTRACT
A 2-D digital filter is discrete system that can be used to process 2-D discrete signals. In this chapter, 2-D continuous and discrete signals are introduced as extensions of their 1-D counterparts. A 2-D continuous signal is physical or contrived quantity that depends on two independent continuous variables t1 and t2. In many applications, 2-D signals arise that are continuous with respect to one variable and discrete with respect to the other variable. A useful concept in the description of 2-D discrete signals is the region of support. The importance of separability arises from the fact that if the output of a 2-D digital filter can be expressed as a product of two 1-D discrete signals, then the design of the filter can be broken down into the design of two 1-D filters. Two types of 2-D digital filters can be identified, namely, recursive and nonrecursive, and like their 1-D counterparts, they can be characterized in terms of difference equations.
