Removal of subjective redundancy from DCT-coded images

The removal of subjective redundancy from video images has recently become an important area of study. A suggested method of removing this redundancy from transform-coded images is through the psychovisual thresholding and quantisation of the image transform coefficients. In this paper, the coefficient thresholding and quantisation levels are based on the combined effects of spatial masking and the varying sensitivity of the human visual system to different spatial frequencies and levels of luminance. By combining the discrete cosine transform (DCT) method of image coding with psychovisual thresholding and quantisation schemes, subdistortion motion video bit-rates as low as 2.5 Mbit/s (non-interlaced 25 frame-per-second video) have been obtained without the need for interframe coding.<>