Wavelet-Based Image Coding Using All-Pass Filters


FIR wavelet filters are mainly used in conventional wavelet-based image coding. However, FIR filters, except for the Haar wavelet, cannot satisfy both the exactly linear phase and orthonormality conditions. For example, the well-known Daubechies-9/7 wavelet is biorthogonal. In this paper, an effective implementation of the all-passbased wavelet filters is presented for wavelet-based image coding. Since all-pass filters are IIR, both the exactly linear phase and orthonormality conditions can be simultaneously satisfied, so that better compression performance can be expected. Also, IIR filters can be realized with a lower computational complexity than can FIR filters. Finally, the proposed IIR wavelet filters are evaluated by using SPIHT to compress the practical images, and the influence of the all-pass filters and delay elements on the compression performance is investigated. It is shown through the experi mental results that the IIR wavelet filters proposed in this paper have a lower computational complexity than the Daubechies-9/7 wavelet, with a comparable compression performance. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 85(2): 13–21, 2002


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