Limited color display for compressed image and video

Many display devices nowadays still allow a limited number of colors, calle d color palette, to be displayed simultaneously. Besides, images and videos in most World Wide Web databases are in compressed formats. Therefore, it becomes an important issue to retrieve a suitable color palette from compre ssed domain in order to have fast and faithful color reproduction for these devices. In this paper, the color-palette design methods for compressed im ages and videos are presented. The proposed approaches use the reduced, rat her than the whole, image for the color palette design to avoid the heavy c omputation in image or video decompression. Also, for compressed videos, a shifting-window scheme is proposed to smooth out color variations in the ch ange of color palette. In these methods, we extend the dependent scalar qua ntization algorithm of a single image to accomplish the color palette desig n. Experimental results show that output image quality of proposed methods is acceptable to human eyes. In addition, empirical results show that the p roposed shifting-window scheme can reduce the main problem of displaying qu antized image sequences, screen flicker.