Minimal and low-sensitivity implementations for a class of two-dimensional digital filters

It is established that 2D denominator-separable transfer functions can be expanded as linear combinations of first-order real or complex coefficient all-pass structures. Using this expansion, the implementation of 2D denominator-separable filters is discussed for the processing of real sequences. These implementations are based on complex coefficient first-order all-pass structures. An efficient structure which needs the minimum number of delays and the minimum number of complex multipliers is also presented