Efficient implementation of undecimated directional filter banks

In this paper, an efficient method to implement undecimated directional filter banks (UDFBs) is proposed. The method is based on an observation that many non-separable two-dimensional two-channel FBs can be efficiently implemented by a separable structure if their polyphase components are separable. Therefore, with appropriate delay and advance blocks, undecimated non-separable FBs can be computed with a comparable computational complexity to the separable case. Structures for 2-, 4- and 8-channel UDFBs are presented to illustrate the idea.