المجلة الدولية للعلوم والتقنية

An adaptive coding technique of gray level images using Periodic Walsh Piecewise-Linear (PWL) transform will be presented in this paper. In this technique the image sub-blocks are divided into four classes according to the level of image activity. The ac energy is used as a measure of the sub-block activity. Adaptivity is obtained by distributing bits among glasses. More bits are assigned to classes of higher activity and fewer bits to lower activity classes. The coding method employs an integer bit allocation scheme and Llyod-Max quantizers. Comparison of coding real images using the adaptive and non-adaptive schemes is given. Computer simulation results indicate that the image coding efficiency using the adaptive technique gives better performance than the non-adaptive scheme from the Peak Signal-to-Noise Ratio (PSNR) viewpoint of the reconstructed images at the expense of a slight increase in complexity........... Keywords: An adaptive coding, (PWL), image, bit ,(PSNR).