The design of arbitrary 2-D zero-phase FIR filters using transformations

The design of 2-D FIR zero-phase filters by transformations is a popular and well-developed technique, but it suffers from the disadvantage that in its current form only filters with four-quadrant symmetry can be designed. In this contribution a natural generalization is presented which allows the method to be used to design arbitrary zero-phase 2-D FIR filters. This generalization preserves the two most important features of the method-the decoupling of the design problem into one-dimensional and two-dimensional components, and the existence of an efficient structure for realizing the filter.