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Low-complexity multiresolution image compression using wavelet lower trees

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2006年第11期16卷 1437-1444页

作者： Oliver, Jose Malumbres, Manuel P. Univ Valencia Dept Comp Engn Valencia 46022 Spain Miguel Hernandez Univ Dept Phys & Comp Engn Elche 03202 Spain

In this paper, a new image compression algorithm is proposed based on the efficient construction of wavelet coefficient lower trees. The main contribution of the proposed lower-tree wavelet (LTW) encoder is the utilization of coefficient trees' not only as an efficient method of grouping coefficients, but also as a fast way of coding them. Thus, it presents state-of-the-art compression performance, whereas its complexity is lower than the one presented in other wavelet coders, like SPIHT and JPEG 2000. Fast execution is achieved by means of a simple two-pass coding and one-pass decoding algorithm. Moreover, its computation does not require additional lists or complex data structures, so there is no memory overhead. A formal description of the algorithm is provided, while reference software is also given. Numerical results show that our codec works faster than SPIHT and JPEG 2000 (up to three times faster than SPIHT and fifteen times faster than JPEG 2000), with similar coding efficiency.

关键词： image compression low complexity tree-based coding wavelets

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Fast tree-based wavelet image coding with efficient use of memory

Fast tree-based wavelet image coding with efficient use of m...

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Conference on Visual Communications and Image Processing 2005

作者： Oliver, J Malumbres, MP Univ Politecn Valencia Dept Comp Engn Valencia 46022 Spain

ISBN: (纸本)0819459763

In this paper, we present a new wavelet image encoder that focuses on overcoming the main drawbacks of other wavelet based-image coders;their high memory requirements and complexity. In our proposal, we tackle these problems in both parts of the wavelet coder, both the DWT algorithm and the coding system. For the DWT, we propose the use of a line-based algorithm, in which we get rid of the wavelet coefficients as soon as they have been calculated. Some previous line-based proposals cannot be easily implemented, and here we describe a recursive algorithm that is implemented more easily. For the coding system, we use a tree-based coder. These coders have evidenced good Rate/Distortion (R/D) performance. However, it has not been clearly shown their excellent possibilities for fast processing of coefficients. Previous tree-based proposals need the entire image in memory to work and so they cannot be used in our system. Other wavelet encoders achieve good R/D performance, but exhibit high complexity. Our proposal is simpler and therefore faster. Numerical results show that the compression performance of our tree-based encoder is equal or better than state-of-the-art coders, such as SPIHT and JPEG 2000, except for highly detailed images. However, the real benefits of our proposal is shown in the amount of memory required, which is reduced drastically (in the order of 25 times less memory than SPIHT and more than 35 times less than JPEG 2000), and in its lower execution time (about four times lower than SPIHT, and more than 20 times lower than JPEG 2000). These results show that our encoder is a good candidate for many embedded systems and other memory-constrained environments, such as digital cameras and PDAs.

关键词： lossy image coding wavelet coding tree-based coding efficient memory usage fast processing

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JBEAM: Multiscale curve coding via beamlets

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2005年第11期14卷 1665-1677页

作者： Huo, XM Chen, JH Georgia Inst Technol Sch ISyE Atlanta GA 30332 USA Emory Univ Hosp Educ Annex Biomed Imaging Technol Ctr Atlanta GA 30322 USA

A multiscale coder for curves and boundaries is presented. It utilizes a multiscale structure-beamlets-that is designed primarily for linear and curvilinear features. The coder is composed of three main components: 1) a rate-distortion optimized beamlet-based representation, 2) a tree-based coding from a beamlet representation to a symbol stream, and 3) an entropy coder. This coder is named "JBEAM." Taking advantage of its multiscale property, we utilized tree-based coding to make it progressive. The derived coder has a low order of computational complexity. Simulations demonstrate an advantage over the state-of-the-art industrial standard: JBIG 2. A software package, which includes an implementation of JBEAM, is made available. Variations and potential improvements of this method will be discussed. This work may inspire more activities in this line of research, improving curve coding.

关键词： beamlet curve coding tree-based coding

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