Dynamic color quantization of video sequences

We present an efficient algorithm for dynamic adaptive color quantization of 24-bit image (video) sequences, important in multimedia applications. Besides producing hifidelity 8-bit imagery, our algorithm runs with minimal computational cost and the generated colormaps are robust to small differences in consecutive images. Apart from the two standard color quantization tasks, colormap design and quantizer mapping, our algorithm includes colormap tilling-an operation unique to dynamic color quantization. This task solves the problem of screen flicker, a serious problem in dynamic quantization of image sequences, resulting from rapid changes in display of colormaps. Our solution is based on two ideas: including in the current colormap a small set of color representatives from the previous image; assigning representatives to the colormap entries in an order that reduces the difference between contents of equal entries in consecutive colormaps. Our algorithm runs in near real time on medium-range workstations.