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Application-specific extensions of a processor provide an efficient mechanism that meets the growing performance and power demands of portable embedded applications such as interactive multimedia communications. This work investigates the use of both the luminance and chrominance components in color image- and video-processing applications and proposes a color-aware instruction set extension (CAX) that improves the performance of color multimedia-processing applications. The CAX ISA is able to exploit a new level of subword parallelism not reachable by current multimedia extensions. Unlike typical multimedia extensions (e.g., Intel MMX, MIPS MDMX, and AMD 3DNow!), CAX instructions support parallel operations on two-packed 16-bit (6:5:5) YCbCr color pixels in a 32-bit datapath width and obtain substantial performance and code density improvements through direct support for color data processing rather than depending solely on generic subword parallelism. The results on a set of media benchmark applications indicate that the CAX versions achieve a speedup ranging from 3x to 5.8x while reducing energy consumption from 68% to 83% over the baseline versions on an identically-configured, dynamically-scheduled superscalar processor. The CAX versions also outperform the MDMX (MIPS multimedia extension) performance.