Improved texture compression for S3TC

Texture compression is a specialized form of still image compression employed in computer graphics systems to reduce memory bandwidth consumption. Modern texture compression schemes cannot generate satisfactory qualities for both alpha channel and color channel of texture images. We propose a novel texture compression scheme, named ImTC, based on the insight into the essential difference between transparency and color. ImTC defines new data formats and compresses the two channels flexibly. While keeping the same compression ratio as the de facto standard texture compression scheme, ImTC improves compression qualities of both channels. The average PSNR score of alpha channel is improved by about 0.2 dB, and that of color channel can be increased by 6.50 dB over a set of test images, which makes ImTC a better substitute for the standard scheme.