A DC coefficient estimation scheme for image coding

Cham and Clarke (1984) proposed three schemes which eliminate the need of transmitting DC coefficients by estimating them from the AC component in transform image coding. Images thus generated however have inherent errors which degrade the image visual quality. We propose a new iteration method which estimates DC coefficients from the AC component and a small portion of DC coefficients. Experiments show that an image coded using the JPEG scheme can be represented using only 10% of its DC coefficients with no or only small visible degradation in image quality. As a result about 4% to 12% more bit reduction can be achieved than the original JPEG scheme.<
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