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Abstract : |
Artifacts in images compressed with the discrete cosine transform (DCT) are a direct result of quantization of the DCT coefficients, and the quantization error in the spatial domain can be expressed as a sum of the DCT basis functions multiplied by the quantization error of the DCT coefficients. This paper provides a statistical description of the spatial-domain quantization noise that shows, among other things, why the notorious blocking artifacts occur in compressed images. An accurate description of quantization noise is essential if one hopes to remove, or at least alleviate, the visibility of compression artifacts. 1., |
