Abstract: Representations of color images are discussed with regard to the problem of color image coding. Standard color image representations are seen to have components with considerable redundancy, and, accordingly are ill-suited for coding using standard gray-scale image coders. The notion of an uncorrelated or orthogonal representation, in which component images are independent in an L$-2$/ sense, is introduced and is shown to have features desirable as a preprocessor to a color image coder. Experiments using both spatial-domain and frequency-domain coders show that the orthogonal representation leads to a 20% - 70% compression ratio improvement over that of RGB or YIQ representations, with less visually objectionable artifacts at low peak signal-to-noise ratios.!5
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