PICTURE QUALITY DETERIORATION DETECTION SYSTEM FOR TELEVISION SIGNAL

摘要

PURPOSE:To improve the quality of a decoded image by estimating a transmission line error by performing edge component decision which detects the presence of an edge component, and comparison with a threshold value decided by the error propagation amplitude of quantize characteristic. CONSTITUTION:Subtractor 5-7 calculate (x-a) to (x-c), respectively based on read in picture elements (a-c), X, and a result is outputted to absolute value calculation parts 9-11 and a sign decision part 8. The sign decision part 8 checks a condition of (x-a) to (x-c) 0 or (x-a) to (x-c)0, and the result is outputted to a minimum value selection part 12. The minimum value selection part 12 outputs the minimum value to a comparative decision part 13 by the output of the sign decision part 8, and the comparative decision part 13 compares the minimum value from the minimum value selection part with the threshold value Th, and when the condition is satisfied, the correction instruction signal of the picture element X is outputted to an error correction part 14. Thereby, it is possible to heighten the detecting accuracy of a faulty picture element without increasing additional information such as an error correction code, and to improve the quality of the decoded image.