Patent ID: 6983016

Claim:
A method for detecting errors in an image signal, in which the image signal is produced by dividing an image into image blocks, and a coding stage is performed in which at least predictive coding is performed on an image block to produce inter-coded image information for said image block, said inter-coded image information comprising at least one prediction error block containing prediction error information, and a decoding stage is performed to recover prediction error information contained in said at least one prediction error block, wherein a prediction error block check is performed in which prediction error information contained in said at least one prediction error block is examined to detect errors in the inter-coded image information for the image block, said inter-coded image information for the image block comprises a macroblock comprising at least one luminance prediction error block containing prediction, error information relating to a luminance component of the image signal and at least one chrominance prediction error block containing prediction error information relating to a chrominance component of the image signal, said image signal comprising at least one chrominance component, the prediction error information contained in said at least one luminance prediction error block and said at least one chrominance prediction error block of said macroblock comprise pixel error values and said pixel error values of said at least one luminance prediction error block and said pixel error values of said a least one chrominance prediction error block are filtered to determine pixel error values of said at least one luminance prediction error block and said at least one chrominance prediction error block which are significant with respect to a threshold value and a third comparison stage is performed in which significant pixel error values comprised by said at least one chrominance prediction error block of said macroblock are compared with pixel error values at corresponding locations in said at least one luminance prediction error block, wherein if the number of locations for which a pixel error value in said at least one chrominance prediction error block is significant with respect to said threshold value and a pixel error value at a corresponding location in said at least one luminance prediction error block is not significant with respect to said threshold value exceeds a fourth value range, the inter-coded image information for the image block is considered to contain at least one error.