Producing color-indexed images with scalable color and spatial resolutions

摘要

Making the media content to be delivered over the Internet to clients of various capabilities scalable is crucial to improve the efficiency of various involved parties. GIF is one of the primary Web file formats used in Web applications nowadays and hence it is desirable to make them scalable as well. However, as GIF format is purposely designed for supporting clients of limited decoding capability, the scalability should be introduced with only a small increase in decoder complexity and bitstream overhead. This paper presents an algorithm that is able to produce color-indexed images with scalable color and spatial resolutions. Downscaled versions of an color-indexed image can be obtained by just bit-cropping and/or down-sampling the index plane of the image.