Patent ID: 8194734

Claim:
A picture decoding method for decoding each of a plurality of coded pictures, per block, by using a quantization matrix with a step being executed by a processor, said method comprising the following steps: obtaining, from a coded stream, a second quantization matrix other than a default quantization matrix and identification information for identifying the second quantization matrix, and holding the second quantization matrix and the identification information; extracting, from the coded stream, a matrix ID which is added to data generated by coding a current picture and is used for identifying a quantization matrix that has been used to code the current picture; identifying, from the quantization matrices held in said holding, a quantization matrix corresponding to the matrix ID; and decoding the data of the current picture using the identified quantization matrix, wherein each picture is made up of a luma component and two chroma components, and in the identifying step, in the case where there is no quantization matrix for one of the two chroma components in the quantization matrices identified based on the identification information, a quantization matrix for the other of the two chroma components is identified as the quantization matrix to be used for the one of the two chroma components.