Generalized Linear-Phase Paraunitary Nonuniform Filter Banks

Uniform filter banks such as the DCT used in JPEG and MPEG have been studied widely. On the other hand, the frequency characteristics of the signal have irregularity. The wavelet transform makes use of such characteristics in nonuniform processing. However, the conventional nonuniform filter banks are constructed with a tree structure of identical two-channel filter banks. Since the frequency characteristic of each subband filter cannot be designed directly, such a filter bank may not be optimum with regard to the coding efficiency. In the present paper, a method of configuration of generalized linear-phase paraunitary nonuniform filter banks is presented. A realization using a lattice structure that preserves orthogonality and the linearphase property is proposed. Finally, the obtained nonuniform filter bank is applied to image coding and the effectiveness of the proposed method is confirmed.