DESIGN OF 2-D PERFECT RECONSTRUCTION FILTER BANKS USING TRANSFORMATIONS OF VARIABLES - IIR CASE

In [1], the authors presented a design technique for 2-channel multidi mensional filter banks. The technique is based on the transformation o f variables and provides the flexibility of controlling the frequency characteristics of the resulting subband filters with ease. Furthermor e, there are several properties of the filters which allow for efficie nt implementation. The transformation functions used in [1] are FIR an d the subband filters are all FIR. In this paper we extend the design technique to yield IIR filters. We emphasize the 2-D diamond subband c ase (with quincunx sampling) but the technique can be used for the par allelogram and diagonally quadrant subband cases as well. The IIR natu re of the filters occurs from the use of IIR transformation functions instead of FIR. Two cases are considered. The first is with zero-phase IIR transformations which yield linear phase subband filters but requ ire noncausal filtering. The second is with nonlinear phase IIR transf ormations which yield nonlinear phase subband filters that can be impl emented in a causal manner.