A method for the design of a class of 2-D IIR variable cutoff boundary filters

Abstract

In this paper we present a method for the design of a class of 2-D IIR filters with variable cutoff boundary. The transfer function of this class of 2-D filters has a zero phase 2-variable polynomial in z1 and 22 in the numerator and two separable polynomials [D1(zl), D2(z2)] in the denominator respectively. The transfomtion used for changing the cutoff boundary are Oppenheim's [l] for the numerator and spectral transformation [2,3] for the denominator of the transfer function respectively.Through examples it is shown that the propsed method results in 2-D filters having better circular contours than the existing techniques. This technique also allows one to perfom circular to elliptic transformation.