Design of 2-D approximately zero-phase separable IIR filters using genetic algorithms

The paper presents a method for designing approximately zero-phase 2-D IIR filters with a quadrantally symmetric magnitude response. The method is based on two error criteria: equiripple error criterion in the passband and least-squared error criterion in the stopband. The filter design problem is transformed into an equivalent bicriterion optimization problem which is converted into a single criterion optimization problem using the weighted sum strategy. The stability constraints are explicitly included into this problem. A two-step solution procedure of the considered problem is proposed. In the first step, a genetic algorithm is applied. The final point from the genetic algorithm is used as the starting point for a local optimization method. A design example is given to illustrate the proposed technique.