Patent ID: 8213495

Claim:
A picture decoding method for decoding coded data including coded blocks on a block-by-block basis, and smoothing, using a deblocking filter, blocking distortion for each of the decoded blocks, the blocking distortion occurring at a boundary between decoded blocks, said method comprising: detecting whether or not each of the blocks included in the coded data contains an error; replacing pixel values of pixels in a block that contains an error with pixel values of corresponding co-located pixels of a co-located block in a reference picture by regarding the block that contains the error as a block which has been inter-picture coded with a motion vector of zero; adding, to the block in which the pixel values have been replaced in said replacing, additional information indicating that the block is a block which has been inter-picture coded with a motion vector of zero; and determining, using different methods depending on a result of said detecting, (i) whether or not filtering should be performed on a boundary between two adjacent blocks, and (ii) which one of a plurality of deblocking filters with different smoothing levels should be used for the filtering of the boundary between the two adjacent blocks when it is determined that the filtering should be performed on the boundary between the two adjacent blocks, wherein, for the block to which the additional information is added, said determining uses a same method as for a block that contains no error for determining (i) whether or not the filtering should be performed and (ii) which one of the plurality of deblocking filters should be used for the filtering, and wherein when it is detected that both of the two adjacent blocks contain an error, said determining determines that the filtering should not be performed on the boundary between the two adjacent blocks.