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A two-layered wavelet-based algorithm for efficient lossless and lossy image compression

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2000年第7期10卷 1094-1102页

作者： Marpe, D Blättermann, G Ricke, J Maass, P Heinrich Hertz Inst Commun Technol Image Proc Dept Berlin Germany Humboldt Univ Charite Dept Radiol Berlin Germany Univ Bremen Dept Math Bremen Germany

In this paper, we propose a wavelet-based image-coding scheme allowing lossless and lossy compression, simultaneously, Our two-layered approach utilizes the best of two worlds: it uses a highly performing wavelet-based or wavelet packet-based coding technique for lossy compression in the low bit range as a first stage. For the second (optional) stage, we extend the concept of reversible integer wavelet transforms to the more flexible class of adaptive reversible integer wavelet packet transforms which are based on the generation of a whole library of bases, from which the best representation for a given residue between the reconstructed lossy compressed image and the original image is chosen using a fast-search algorithm. We present experimental results demonstrating that our compression algorithm yields a rate-distortion performance similar or superior to the best currently published pure lossy still image-coding methods, At the same time, the lossless compression performance of our two-layered scheme is comparable to that of state-of-the-art pure lossless image-coding schemes. Compared to other combined lossy/lossless coding schemes such as the emerging JPEG-2000 still image-coding standard PSNR improvements up to 3 dB are achieved for a set of standard test images.

关键词： best-basis algorithm lossless image coding lossy image compression wavelet transform

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Evolutionary-based methods for adaptive signal representation

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SIGNAL PROCESSING 2001年第5期81卷 927-944页

作者： da Silva, ARF Univ Nova Lisboa Dept Elect Engn P-2825 Monte De Caparica Portugal

In spite of the good decomposition properties offered by wavelet-packet bases, it is well known that more flexible decompositions are required. On the other hand, one well known disadvantage of wavelet transforms is the lack of shift invariance. We propose the use of an evolutionary approach as the main tool for searching adaptive signal representations. The algorithm generates a population of solutions based on basis expansions of multi-filter, time-shifted, wavelet-packet libraries. The approach of organizing libraries of bases as a tree has been extended to construct a joint tree, to guide the process of generating shifted wavelet-packet transforms. The standard time-frequency diagram has been extended to enable the representation of shifted packet basis. We show that the evolutionary approach may be used as a flexible tool for obtaining signal representations in overcomplete dictionaries. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： wavelet packet best-basis algorithm evolutionary optimization

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