A class of 2-D separable denominator filters designed via the McClellan transform

This paper presents a technique for separating the denominator of a particular class of 2-D zero-phase second-order filters, designed via the McClellan transform. It is found that when the transform is restricted only to the first-order, the condition for separability of the denominator of the 2-D zero-phase filter is that the 1-D prototype be critically damped. Examples are given for filters with elliptical and circular isopotential contours. Results show that the simplicity of the design, and the robustness and modularity of the implementation associated with separable denominators and with the cascading of low-order sections, far outweigh the restriction imposed by a critically damped response.