Design of 2-dimensional digital filters using 2-D all-pass building blocks

In this paper a method for the design of 2-D recursive digital filters with arbitrary magnitude characteristics, by using all-pass building blocks, is presented. It is shown that in general, cascade of sum or difference of two 2-D all-pass filters with appropriate delay elements are required to guarantee the arbitrary shape of the cutoff boundary of the desired filter. A design example is given to illustrate the usefulness of the proposed technique