Importance

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Abstract

Errors are detected in a decoded video signal that has been processed at least partly in data blocks, such as MPEG-2 compression macroblocks or other block processed data, by discerning the appearance of a pattern of contrast in the decoded output video signal around the perimeter of an area corresponding to a processed block of pixels. In a compression technique, an error affecting one more members of a block of pixels generally affects the entire block. In the absence of an error, processed blocks most typically merge imperceptibly into one another with pixel values may that change little, if at all, across the border between abutting blocks. The error alters this situation and makes at least one of the blocks perceptible among the abutting blocks due to distinct contrast between the blocks. Image processing techniques are employed to discern an apparent block and thereby to discriminate for errors. The errors can be handled as appropriate, such as by generating an alarm, triggering a substitution of signal sources, repeating a stored block or the like.

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First Claim