Color Space Selection for JPEG Image Compression

The Joint Photographic Experts Group's image compression algorithm has been shown to be a very efficient and powerful method of compressing images. However, there is litde substantive information about which color space should be utilized when implementing the JPEG algorithm. Currendy, the JPEG algorithm is set up for use with any three component color space. The objective of this research was to determine whether or not the color space selected will significandy improve image compression capabilities. The RGB, XYZ, YIQ, CIELAB, CIELUV, and CIELAB LCh color spaces were examined and compared. Both numerical measures and psychophysical techniques were used to assess the results. The final results indicate that the device space, RGB, is the worst color space to compress images. In comparison, the nonlinear transforms of the device space, CIELAB and CIELUV, are the best color spaces to compress images. The XYZ, YIQ, and CIELAB LCh color spaces resulted in intermediate levels of compression.