Design of 2-dimensional circularly-symmetric digital filters

A simple method which can be used to design 2-dimensional circularly-symmetric recursive lowpass digital filters is described. The design problem is transformed into an unconstrained minimax optimisation problem. A recently proposed minimax algorithm due to Charalambous was used to obtain the numerical results presented in the paper. 80 design examples are solved, using the present approach, that illustrate the usefulness of the new approach to the design of 2-dimensional recursive digital filters.