Design of 2-D recursive digital filters with non-circular symmetric cut-off boundary and constant group-delay responses

A method is presented for generating a one-variable Hurwitz polynomial using properties of the positive definite matrices coupled with resistance matrices. Also, the authors test the two-term and three-term separable-denominator transfer functions for their effectiveness in the design of two-dimensional (2-D), noncircular, symmetric 2-D filters with constant group-delay specification. While both transfer functions yield satisfactory results, the two-term separate denominator filter requires more multipliers than the three-term separate denominator filter, making the former more economical to design and implement