In this paper, two simple yet efficient embedded block-based image compression algorithms are presented. These algorithms not only improve the rate distortion performances of set partitioning in hierarchical trees (SP...
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In this paper, two simple yet efficient embedded block-based image compression algorithms are presented. These algorithms not only improve the rate distortion performances of set partitioning in hierarchical trees (SPIHT) and set partitioning in embedded block coder (SPECK) at lower bit rates but also reduces the dynamic memory requirement by 91.1% in comparison to SPIHT. The former objective is achieved by better exploiting the coefficient decaying spectrum of the wavelet transformd images and the later objective is realised by improved listless implementation of the algorithms. The proposed algorithms explicitly perform breadth first search like SPECK. Extensive simulation conducted on various standard grayscale and color images indicate significant peak-signal-to-noise-ratio (PSNR) improvement over most of the state-of-the-art wavelet-based embedded coders including JPEG2000 at lower rates. The reduction of encoding and decoding time as well as improvement in coding efficiency at lower bit rates facilitate these coder as better candidates for multimedia applications.
This paper presents a listless variant of modified wavelet block tree coding (MLBTC) algorithm. Wavelet block-tree coding (WBTC) improves the image compression performance of set partitioning in hierarchical trees (SP...
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This paper presents a listless variant of modified wavelet block tree coding (MLBTC) algorithm. Wavelet block-tree coding (WBTC) improves the image compression performance of set partitioning in hierarchical trees (SPIHT) at lower rates by efficiently encoding both inter- and intra-scale correlations. The use of auxiliary lists makes WBTC undesirable for hardware implementation as it needs a lot of memory management due to exponential increase of nodes on each pass. The proposed coder named as hierarchical listless block-tree DTT (HLBT DTT) that combines discrete Tchebichef transform (DTT) with MLBTC exhibits compression performance significantly higher than most of the DCT-based embedded coders and comparable with JPEG 2000, especially at lower bit rates. Further, HLBT DTT requires only 10% of memory than that of DCT-based SPIHT/WBTC coders.
This paper presents a listless implementation of wavelet based block tree coding (WBTC) algorithm of varying root block sizes. WBTC algorithm improves the image compression performance of set partitioning in hierarchi...
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This paper presents a listless implementation of wavelet based block tree coding (WBTC) algorithm of varying root block sizes. WBTC algorithm improves the image compression performance of set partitioning in hierarchical trees (SPIHT) at lower rates by efficiently encoding both inter and intra scale correlation using block trees. Though WBTC lowers the memory requirement by using block trees compared to SPIHT, it makes use of three ordered auxiliary lists. This feature makes WBTC undesirable for hardware implementation;as it needs a lot of memory management when the list nodes grow exponentially on each pass. The proposed listless implementation of WBTC algorithm uses special markers instead of lists. This reduces dynamic memory requirement by 88% with respect to WBTC and 89% with respect to SPIHT. The proposed algorithm is combined with discrete cosine transform (DCT) and discrete wavelet transform (DWT) to show its superiority over DCT and DWT based embedded coders, including JPEG 2000 at lower rates. The compression performance on most of the standard test images is nearly same as WBTC, and outperforms SPIHT by a wide margin particularly at lower bit rates. Crown Copyright (c) 2012 Published by Elsevier GmbH. All rights reserved.
A new embedded wavelet coder called the multithreshold wavelet coder (MTWC) was proposed in this research. The new coder was motivated by a careful analysis of the rate-distortion performance and the coding efficiency...
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ISBN:
(纸本)0819425869
A new embedded wavelet coder called the multithreshold wavelet coder (MTWC) was proposed in this research. The new coder was motivated by a careful analysis of the rate-distortion performance and the coding efficiency of existing embedded wavelet coders. Unlike other proposed embedded wavelet coders which use a single initial threshold in their successive approximate quantization (SAQ), MTWC uses different initial thresholds in different subbands and applies a subband decision scheme to decide which subband should be coded in sequence. It is shown with experimental results that MTWC has a better rate-distortion tradeoff at higher bit rates and a lower computational complexity than other embedded wavelet coders. Furthermore, MTWC can be easily applied to an image coder with the wavelet packet transform, whose performance is significantly better than the image coder with the pyramid wavelet transform for texture-dominant imagery.
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