A design theory of stable 2-D recursive digital filters

Present a new method of designing 2-D IIR (infinite impulse response) digital filters taking into account the stability in a self-consistent manner by means of the interpolation of the transfer functions by two-variable rational functions. The general theory is first outlined. Then, a design method is presented with special emphasis on the approximation of the circularly symmetric characteristics and, simultaneously, the degree economization. As a typical example, a Chebyshev-type filter is illustrated to show the effectiveness of the proposed method