Many standard image ompreion techniques involve applying discrete COS1nC transforms (DCTs) to the cornponents comprising a color image and quantizing the resulting transform coefficients. Such techniques can be applied to color images in any color coordinate space. To achieve maximum compression, the DCT coefficients ShOUld he quantized as coarsely as possible, while allowing no visible distortion in the decompressed image. Due to variations in the contrast sensitivity of the human visual

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... as a function of spatial frequency, different l)(;I' coefficients require different precision in their quantization in order to iiicet thjs goal. I)ifferent color cornponents may also have different quantization requirements. In this paper we propose a l)Cl' COeffiCient quantization scheme for color iniages in the RGJJ color space. We will describe experiments performed to determine human visual system sensitivity to the E)Ci basis functions in the RG1J space, and how the results from these experitnenis are used to design the quantization scheme. We will then compare our qiiantizat.ion scheme to other techniques proposed for images in the kGB and Y(7rch color spaces, in terms of quality of the decompressed images, and data conipression achieved.