2-D separable digital filters

A known method to design 2-D filters is to transform the design problem from the 2-D to the 1-D domain by decomposing the 2-D specification into a sum of separable specification components. The filter used for the approximation is taken in the form of a sum of separable 2-D filters (i.e. a separable denominator filter). In this paper a framework that encompasses the available decomposition techniques is presented. Other techniques with desirable characteristics are proposed. The definition of separability is also extended to include filters with general impulse response support.