Image decoding method
An image decoding method includes: dividing a current block into sub-blocks; deriving, for each sub-block, one or more prediction information candidates; obtaining an index; and decoding the current block using the prediction information candidate selected by the index. The deriving includes: determining whether a neighboring block neighboring each sub-block is included in the current block, and when not included in the current block, determining the neighboring block to be a reference block available to the sub-block, and when included in the current block, determining the neighboring block not to be the reference block; and deriving a prediction information candidate of the sub-block from prediction information of the reference block; and when the number of prediction information candidates is smaller than a predetermined number, generating one or more new candidates without using the prediction information of the reference block till the number of prediction information candidates reaches the predetermined number.
1. A decoding method for decoding an image included in a bitstream, the method comprising:
dividing a current block into a plurality of partitions including a first partition;
deriving one or more prediction information candidates, each of the one or more prediction information candidates being a candidate for prediction information indicating a motion vector;
obtaining, from the bitstream, an index for selecting a prediction information candidate to be used for predicting the current block from among the one or more prediction information candidates; and
decoding the current block using the prediction information candidate selected by the index,
wherein the deriving includes:
when a second partition neighboring the first partition is not included in the current block, determining the second partition to be a reference block available to the first partition;
when the second partition is included in the current block, determining the second partition not to be the reference block; and
deriving a prediction information candidate of the first partition from prediction information of the reference block.
2. A decoding apparatus which decodes an image included in a bitstream, the decoding apparatus comprising:
a division unit configured to divide a current block into a plurality of partitions including a first partition;
a deriving unit configured to derive one or more prediction information candidates, each of the one or more prediction information candidates being a candidate for prediction information indicating a motion vector;
an index obtainment unit configured to obtain, from the bitstream, an index for selecting a prediction information candidate to be used for predicting the current block from among the one or more prediction information candidates; and
a decoding unit configured to decode the current block using the prediction information candidate selected by the index,
wherein the deriving unit is configured to:
when a second partition neighboring the first partition is not included in the current block, determined the second partition to be a reference block available to the first partition;
when the second partition is included in the current block, determine the second partition not to be the reference block; and
derive a prediction information candidate of the first partition from prediction information of the reference block.
3. A decoding apparatus which decodes an image included in a bitstream, the decoding apparatus comprising:
storage; and
processing circuitry that is coupled to the storage and executes the decoding, wherein the decoding includes:
dividing a current block into a plurality of partitions including a first partition;
deriving one or more prediction information candidates, each of the one or more prediction information candidates being a candidate for prediction information indicating a motion vector;
obtaining, from the bitstream, an index for selecting a prediction information candidate to be used for predicting the current block from among the one or more prediction information candidates; and
decoding the current block using the prediction information candidate selected by the index,
wherein the deriving includes:
when a second partition neighboring the first partition is not included in the current block, determining the second partition to be a reference block available to the first partition;
when the second partition is included in the current block, determining the second partition not to be the reference block; and
deriving a prediction information candidate of the first partition from prediction information of the reference block.