Design of 2-D digital filters with octagonal passband and stopband boundaries

A method for the design of 2-D digital filters with octagonal passband and stopband boundaries is described. The method involves cascading four 1-D FIR (finite impulse response) or IIR (infinite impulse response) digital filters. Consequently, it is easy to apply and leads to fast, economical, and efficient designs. By choosing appropriate passband- and stopband-edge frequencies for the 1-D filters, 2-D filters with approximately circular or elliptical passband and stopband boundaries can readily be designed. Additionally, it is possible to realize causal 2-D IIR filters with linear-phase passbands by using 1-D IIR filters having linear-phase passbands.<
>