Color Image Compression Algorithm Based on the DCT Blocks
  This paper presents the performance of different blockbased discrete cosine transform (DCT) algorithms for compressing color image. In this RGB component of color image are converted to YCbCr before DCT transform is applied. Y is luminance component;Cb and Cr are chrominance components of the image. The modification of the image data is done based on the classification of image blocks to edge blocks and non-edge blocks, then the edge block of the image is compressed with low compression and the nonedge blocks is compressed with high compression. The analysis results have indicated that the performance of the suggested method is much better, where the constructed images are less distorted and compressed with higher factor. 
Walaa M. Abd-Elhafiez, Wajeb Gharibi
cs.CV