I.H. Jang, S.H. Kim, and N.C. Kim (Korea)
Image coding, fractal image coding,LMSE, contractive mapping.
In this paper, we propose a fast fractal image coding based on LMSE (least mean square error) analysis and subblock feature. The proposed method is focused on efficient search of the contrast scaling, position of its matched domain block, and isometric transform for a range block. The contrast scaling and the domain block position are searched using a cost function that comes from the LMSE analysis of the range block and its fractal approximated block. The isometric transform is searched using 2×2 blocks formed with the averages of subblocks of range block and domain block. Experimental results show that the encoding time of a conventional fractal image coding with our search method is 25.6−30.3 times faster than that with full search method at the same bit rates while giving PNSR decrement of 0.3−0.4 dB with negligible deterioration in subjective quality. It is also shown that the encoding time of the Jacquin’s fractal image coding with our search method is 4.4−4.6 times faster than the original Jacquin’s fractal image coding and is superior by maximum 0.4 dB in PSNR. It also yields reconstructed images of better quality.
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