Application of an efficient parallel IIR filter bank to image subband coding

Abstract

The principle of subband coding has recently been successfully applied for the purpose of image data compression. The analysis/synthesis filter banks and the subband signal encoder/decoder are the main parts of a subband coder. Previously the filter banks in image subband coders have been designed with FIR filters organized in a tree structure. In this paper we propose a novel structure that deviates from previously reported structures in these respects: (1) The filter bank is organized as a parallel structure. (2) The filters employed are 1st order IIR allpass filters featuring very low computational complexity. (3) The resulting subbands are complex. (4) The filter bank features exact reconstruction in the absence of encoding/decoding. In the paper we give a detailed derivation of the filter bank structure. The computational complexity is evaluated and shown to be considerably less than that of existing structures. We have incorporated this filter bank structure into a complete image subband coder. Finally, coding results obtained by computer simulation are presented.