Symmetry and 2-D recursive digital filtering

The author presents 2-D recursive digital filters with linear phase and describes their applications to 2-D digital signal processing. Four kinds of linear-phase 2-D recursive digital filtering patterns and 16 corresponding linear-phase expressions of the transfer function are proposed. The advantages of these systems are simplicity and high efficiency, but they are difficult to use in real time because of the unavoidable time delay in processing