Design of circularly symmetric low-pass two-dimensional FIR digital filters

A technique for choosing the coefficients of the first-order McClellan transformation for the design of circularly symmetric twodimensional FIR filters from one-dimensional filters is described. It is shown that, by a simple analytic technique, it is possible to determine the coefficients so as to make the passband boundary of a two-dimensional filter to approximate a circle with a high degree of accuracy. The behavior of the transformed filter in the transition region is discussed and a design example to meet a given set of specifications is given.