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, on a block-by-block basis, an image included in a bitstream, the method comprising:
dividing a current block that is a unit of decoding into a plurality of sub-blocks each of which is a unit of prediction;
deriving, for each of the plurality of sub-blocks, one or more prediction information candidates each of which is a candidate for prediction information indicating a reference picture list, a motion vector, and a reference picture index; and
decoding the current block using the one or more prediction information candidates,
wherein the deriving includes:
determining, for each adjacent block that is adjacent to a sub-block among the plurality of sub-blocks, whether the adjacent block is included in the current block or not included in the current block, and determining a block not included in the current block to be a reference block available to the sub-block;
determining a block included in the current block not to be the reference block; and
deriving a prediction information candidate of the sub-block from the predication information of the reference block.
2. A decoding apparatus which decodes, on a block-by-block basis, an image included in a bitstream, the apparatus comprising:
a division unit configured to divide a current block that is a unit of decoding into a plurality of sub-blocks each of which is a unit of prediction;
a deriving unit configured to derive, for each of the plurality of sub-blocks, one or more prediction information candidates each of which is a candidate for prediction information indicating a reference picture list, a motion vector, and a reference picture index; and
a decoding unit configured to decode the current block using the one or more prediction information candidates,
wherein the deriving unit is configured to:
determine, for each adjacent block that is adjacent to a sub-block among the plurality of sub-blocks, whether the adjacent block is included in the current block or not included in the current block, and determine a block not included in the current block to be a reference block available to the sub-block;
determine a block included in the current block not to be the reference block; and
derive a prediction information candidate of the sub-block from the predication information of the reference block.
3. A decoding apparatus which decodes, on a block-by-block basis, an image included in a bitstream, the apparatus comprising:
storage; and
processing circuitry that is coupled to the storage and executes the decoding, wherein the decoding includes:
dividing a current block that is a unit of decoding into a plurality of sub-blocks each of which is a unit of prediction;
deriving, for each of the plurality of sub-blocks, one or more prediction information candidates each of which is a candidate for prediction information indicating a reference picture list, a motion vector, and a reference picture index; and
decoding the current block using the one or more prediction information candidates,
wherein the deriving includes:
determining, for each adjacent block that is adjacent to a sub-block among the plurality of sub-blocks, whether the adjacent block is included in the current block or not included in the current block, and determining a block not included in the current block to be a reference block available to the sub-block;
determining a block included in the current block not to be the reference block; and
deriving a prediction information candidate of the sub-block from the predication information of the reference block.