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Inverse quantization of DCT coefficients using Laplacian pdf  

강소연 (이화여자대학교 정보통신학과 영상신호처리 연구실)
이병욱 (이화여자정보통신학과 영상신호처리 연구실)
Publication Information
The Journal of Korean Institute of Communications and Information Sciences / v.29, no.6C, 2004 , pp. 857-864 More about this Journal
Abstract
Many image compression standards such as JPEG, MPEG or H.263 are based on the discrete cosine transform (DCT) and quantization method. Quantization error. is the major source of image quality degradation. The current dequantization method assumes the uniform distribution of the DCT coefficients. Therefore the dequantization value is the center of each quantization interval. However DCT coefficients are regarded to follow Laplacian probability density function (pdf). The center value of each interval is not optimal in reducing squared error. We use mean of the quantization interval assuming Laplacian pdf, and show the effect of correction on image quality. Also, we compare existing quantization error to corrected quantization error in closed form. The effect of PSNR improvements due to the compensation to the real image is in the range of 0.2 ∼0.4 ㏈. The maximum correction value is 1.66 ㏈.
Keywords
image compression; dequantization, quantization error; Laplacian pdf;
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Times Cited By KSCI : 1  (Citation Analysis)
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