Variable-cutoff two-dimensional lowpass f.i.r. digital filters

A recently formulated transformation for implementing 1-dimensional variable-cutoff filters is extended to the design of 2-dimensional variable-cutoff lowpass filters, and it is shown that the cutoff frequencies along the two frequency axes can be independently controlled, each by one parameter. The filters designed with the 1st-order transformation have certain drawbacks, which are shown to be overcome with the 2nd-order transformation with proper constraints on the variable parameters.