Subband Coding of Images Employing an Efficient Parallel Filter Bank
John Håkon Husøy, Tor Audun Ramstad · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1989
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 present the filter bank structure. The computational complexity is evaluated and shown to be considerably lower than that of existing structures. The problem of extension of the finite length signals in a subband coder is mentioned along with a method, recursively formulated circular convolution , for dealing with it. We have incorporated this filter bank structure into a complete image subband coder. Finally, coding results obtained by computer simulation are presented.