Encoder, decoder, encoding method, decoding method, and picture compression program

Abstract

An encoder (100) partitions into blocks using a set of block partition modes obtained by combining one or more block partition modes defining a partition type. The set of block partition modes includes a first partition mode 5 defining the partition direction and number of partitions for partitioning a first block, and a second block partition mode defining the partition direction and number of partitions for partitioning a second block which is one of blocks obtained after the first block is partitioned. When the number of partitions of the first block partition mode is three, the second block is a center block among 10 the blocks obtained after partitioning the first block, and the partition direction of the second block partition mode is same as the partition direction of the first block partition mode, the second block partition mode includes only a block partition mode indicating that the number of partitions is three. 5 10 20 26 23 39 80 15 S ep 2 02 6 2 0 2 6 2 3 3 9 8 0 1 5 S e p 2 0 2 6

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