Filters derived from the addition or subtraction of two m-D all-pass filters
V. Ramachandran, Majid Ahmadi, C.A. Gargour · 2002
Necessary and sufficient conditions are derived (both in m-D analog and discrete domains) which will enable one to realize an m-D transfer function as a sum or a difference of two m-D all-pass transfer functions. This is utilized in the design of 2-D filters whose magnitude response is contained in second and fourth quadrants only.>