Color format conversion in a parallel processor

Abstract

A pixel of a color video image is converted from one color format having luminance and chrominance signals, e.g., YUV format, to a destination format, e.g., RGB or CMY formats, by forming luminance and chrominance component words which include partitioned words representing various color components of the luminance and chrominance signals. The luminance and chrominance component words are summed using a partitioned addition operation to thereby accumulate the various color components of the luminance and chrominance signals simultaneously and in parallel. Formation of the luminance and chrominance component words is, in some instances, done by a load and store unit of a central processing unit while a graphics execution unit simultaneously sums the luminance and chrominance components using the partitioned addition operation. By using this technique, conversion of pixels of a color motion image from YUV format to a different format, e.g., RGB format, is reduced from approximately 20 instruction cycles per pixel to generally less than 2.5 instruction cycles per pixel. Such a reduction in processing requirements has enabled full real-time rendering, e.g., thirty frames per second, of full-sized, digital NTSC, MPEG-compressed, motion video images using only a central processing unit and appropriately configured computer software. No additional, special-purpose hardware components were needed.