Optimal Design of Digital IIR and FIR Filters Using Complex Flatness Constraints: A Unified Approach

A procedure for the design of digital filters with either a finite or infinite impulse response (FIR or IIR) is presented. Complex flatness constraints, incorporating the desired passband group delay, are used to specify the properties of non-linear-phase filters. Solutions are found using a linear combination of basis functions with zero or non-zero poles, for FIR or IIR filters, respectively. The procedure is used to design multidimensional filters for Lucas-Kanade optical flow.