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Optimal reconstruction value for DCT dequantization using laplacian pdf model

Title
Optimal reconstruction value for DCT dequantization using laplacian pdf model
Authors
Kang S.-Y.Lee B.-U.
Ewha Authors
이병욱
SCOPUS Author ID
이병욱scopus
Issue Date
2004
Journal Title
Proceedings of SPIE - The International Society for Optical Engineering
ISSN
0277-786XJCR Link
Citation
vol. 5308, no. PART 2, pp. 1209 - 1217
Indexed
SCOPUS scopus
Abstract
Many image compression standards such as JPEG, MPEG or H.263 are based on the discrete cosine transform (DCT), quantization, and Huffman coding. Quantization error is the major source of image quality degradation. The current dequantization method assumes the uniform distribution of DCT coefficients. Therefore the reconstruction value is the center of each quantization interval. However DCT coefficients are regarded to follow Laplacian probability density function (pdf). We derive an optimal reconstruction value in closed form assuming Laplacian pdf, and show the effect of the correction on image quality. We estimate the Laplacian pdf parameter for each DCT coefficient, and obtain a correction for reconstruction value from the proposed theoretical predictions. The corrected value depends on the Laplacian pdf parameter and the quantization step size Q. The effect of PSNR improvement due to the change in dequantization value is about 0.2 ~ 0.4 dB. We also analyze the reason for the limited improvements.
DOI
10.1117/12.526684
Appears in Collections:
엘텍공과대학 > 전자공학과 > Journal papers
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