Image analysis – Image compression or coding – Including details of decompression
Patent
1995-04-18
1998-09-15
Johns, Andrew W.
Image analysis
Image compression or coding
Including details of decompression
382236, 382238, 382250, 348420, G06K 936, G06K 946, H04N 712
Patent
active
058091734
ABSTRACT:
An video decoder system, such as for use with MPEG video compression, uses a previous B-frame as an additional prediction source for the current B-frame. In one embodiment, a given block within a current B-frame "N" reuses IDCT result terms from the previous B-frame "N-1" if they are determined to be "similar enough" to the anticipated IDCT result terms which would otherwise need to be computed. For a given block, each of the "M" lowest-frequency DCT coefficients for B-frame "N" and B-frame "N-1" are respectively compared: if they differ by less than a similarity threshold value, then the IDCT result terms from the previous B-frame "N-1" are reused without further computation. The similarity threshold may be adaptively adjusted to reduce the computational burden of video decompression, while affording a gradual degradation of picture quality, rather than wholesale skipping of entire frames.
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Tucker Michael R.
Advanced Micro Devices , Inc.
Davis Monica S.
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Johns Andrew W.
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