The principle and theory of SLCCA (Significance Linked Connected Component Analysis) coding technology has been further studied in this paper. To enhance SLCCA, we introduce distance-first significance-linked connecte...
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ISBN:
(纸本)9780780397514
The principle and theory of SLCCA (Significance Linked Connected Component Analysis) coding technology has been further studied in this paper. To enhance SLCCA, we introduce distance-first significance-linked connected component analysis and a combined extension and arithmetic code for symbol sequence. An enhanced SLCCA coding system is constructed. Its PSNR performance is compared with both SLCCA and JPEG2000 on numerous 512x512 gray-scale natural images at three different bit rates, i.e., 0.3, 0.6 and 0.9 bits per pixel. On average, SLCCA+ is superior to SLCCA by 0.45 dB and significantly outperforms JPEG2000 by 3.69 dB. Detailed algorithm and further improvement will be given in a separate paper.
context-basedarithmeticcoding has been widely adopted in image and video compression and is a key component of the new JPEG2000 image compression standard. In this paper, the contexts used in JPEG2000 are analyzed u...
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ISBN:
(纸本)0819448222
context-basedarithmeticcoding has been widely adopted in image and video compression and is a key component of the new JPEG2000 image compression standard. In this paper, the contexts used in JPEG2000 are analyzed using the mutual information, which has a direct link with the compression performance. We first show that, when combining the contexts, the mutual information between the contexts and the encoded data will decrease unless the conditional probability distributions of the combined contexts are the same. Given I, the initial number of contexts, and F, the final desired number of contexts, there are S(I, F) possible context classification schemes where S(1, F) is called the Stirling number of the second kind. The optimal classification scheme is the one that gives the maximum-mutual information. Instead of exhaustive search, the optimal classification scheme can be obtained through a modified Generalized Llyod algorithm with the relative entropy as the distortion metric. For binary arithmeticcoding, the search complexity can be reduced by using the dynamic programming. Our experimental results show that the JPEG2000 contexts capture very well the correlations among the wavelet coefficients. At the same time, the number of contexts used as part of the standard can be reduced without loss in the coding performance.
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