Influence of image segment size on efficiency of SA DCT
[ 1 ] Katedra Systemów Telekomunikacyjnych i Optoelektroniki, Wydział Elektroniki i Telekomunikacji, Politechnika Poznańska | [ P ] employee
2006
paper
english
EN In the paper influence of segments size on the efficiency of SA DCT is analyzed. Namely, it is shown that typical in image compression 8times8-pixel blocks are usually too small for obtaining the best PSNR values. Optimal block size depends on compression ratio, it grows from 12times12 pixels for low compression (more than 1 bit per pixel) up to 32times32 pixels or natural (non-rectangular) segmentation for less than 0.5 bits per pixel. The explanation is obvious, it is required that for a segment at least its DC component should be computed, while the number of blocks is inversely proportional to their size. The difference is also clearly seen when evaluating images subjectively.
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