Encoder, decoder, encoding method, and decoding method
An encoder according to one aspect of the present disclosure encodes a block of an image, and includes a processor and memory connected to the processor. Using the memory, the processor partitions a block into a plurality of sub blocks and encodes a sub block included in the plurality of sub blocks in an encoding process including at least a transform process or a prediction process. The block is partitioned using a multiple partition including at least three odd-numbered child nodes and each of a width and a height of each of the plurality of sub blocks is a power of two.
1. A non-transitory computer readable medium storing a bitstream, comprising:
the bitstream including a parameter according to which a decoder performs:
determining prediction mode information;
determining a set of partition modes in accordance with the prediction mode information;
parsing the parameter from the bitstream;
selecting a partition mode from the set of partition modes in accordance with the parameter;
partitioning a block into a plurality of sub blocks using the selected partition mode; and
decoding a sub block included in the plurality of sub blocks in a decoding process, wherein the decoder performs:
partitioning the block into three sub blocks in response to the parameter indicating a first value, each of a width and a height of each of the three sub blocks being a power of two; and
partitioning the block into an even number of sub blocks in response to the parameter indicating a second value, the second value being different from the first value, each of the even number of sub blocks having a same size.
2. The non-transitory computer readable medium according to claim 1 , wherein the decoder performs:
determining a first set of partition modes in response to the prediction mode information indicating an inter prediction mode; and
determining a second set of partition modes in response to the prediction mode information indicating an intra prediction mode, a partition mode included in the second set of partition modes producing smaller sub blocks than all of sub blocks produced by the first set of partition modes.