Patent ID: 7031393
Filing Date: 2006-04-18
Classification: G01R

Abstract:
1. A block distortion detection method, comprising: receiving a decoded image signal obtained by decoding code sequences which are obtained by dividing an image signal into plural blocks each comprising plural pixels and then coding the image signal using motion compensation for a unit including at least one block, and obtaining a first difference in pixel values between two pixels across the boundary of blocks/motion-compensation-units which is the boundary between adjacent blocks as well as the boundary between adjacent motion compensation units, and a second difference in pixel values between two pixels which belong to a block in the vicinity of the boundary of blocks/motion-compensation-units; and deciding that a block distortion occurs at the boundary of blocks/motion-compensation-units when the absolute value of the first difference is larger than a first threshold value while the absolute value of the second difference is smaller than a second threshold value, and the amount of motion in motion compensation units across the boundary of blocks/motion-compensation-units is larger than a third threshold value, and deciding that a strong block distortion occurs at the boundary of blocks/motion-compensation-units when the first and second threshold values are small, and the amount of motion in motion compensation units across the boundary of blocks/motion-compensation-units is large.