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Abstract

A video signal having a bandwidth on the order of 37 MHz is subjected to adaptive sub-band coding for transmission through a standard 6 MHz NTSC television channel. During each frame of the video signal a plurality of blocks of sub-band coefficients, each block representing the spectral content of a corresponding portion of the video image, are derived. The energy distribution of each block of coefficients is analyzed in a plurality of different spatial directions to establish a perceptual coding classification for each coefficient block. The coefficients are then variably quantized, e.g. truncated, in dependence upon the classification established for the corresponding block to reduce the required transmission bandwidth without introducing significant visible artifacts in the reproduced video image.

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First Claim