Image decoding device and image encoding device
View Patent ↗The present invention avoids waste caused by performing both a Secondary Transform and an Adaptive Multiple Core Transform. Provided is a device including: a core transform unit ( 1521 ) that can perform an Adaptive Multiple Core Transform on a Coding Tree Unit; and a Secondary Transform unit ( 1522 ) that can perform, before the Adaptive Multiple Core Transform, a Secondary Transform on at least any one of sub-blocks included in the Coding Tree Unit. The device omits any of the Adaptive Multiple Core Transform and the Secondary Transform in accordance with at least any of a flag associated with the Adaptive Multiple Core Transform and a flag associated with the Secondary Transform, or in accordance with a size of the Coding Tree Unit.
1. An image decoding device configured to decode a picture by splitting the picture into a Coding Unit, the device comprising:
a first transform circuit configured to be capable of applying a core transform to a transform unit included in the Coding Unit;
a second transform circuit configured to be capable of applying, before the core transform, a secondary transform to the transform unit;
a first decoding circuit configured to be capable of decoding a flag specifying whether or not a first index is present;
a second decoding circuit configured to be capable of decoding the first index associated with the core transform; and
a third decoding circuit configured to be capable of decoding a secondary index associated with the secondary transform,
wherein the second decoding circuit decodes the first index in a case where the secondary index specifies that the secondary transform is not used and in a case where the flag specifies that the first index is present, and
the second decoding circuit derives the first index equal to 0 in a case where the secondary index specifies that the secondary transform is used or in a case where the flag specifies that the first index is not present.
2. An image encoding device configured to encode a picture by splitting the picture into a Coding Unit, the device comprising:
a first transform circuit configured to be capable of applying a core transform to a transform unit included in the Coding Unit;
a second transform circuit configured to be capable of applying, after the core transform, a secondary transform to the transform unit;
a first encoding circuit configured to be capable of encoding a flag specifying whether or not a first index is present;
a second encoding circuit configured to be capable of encoding the first index associated with the core transform; and
a third encoding circuit configured to be capable of encoding a secondary index associated with the secondary transform,
wherein the second encoding circuit encodes the first index in a case where the secondary index specifies that the secondary transform is not used and in a case where the flag specifies that the first index is present, and
the second encoding circuit derives the first index equal to 0 in a case where the secondary index specifies that the secondary transform is used or in a case where the flag specifies that the first index is not present.
3. An image decoding method for decoding a picture by splitting the picture into a Coding Unit, the method comprising:
applying a core transform to a transform unit included in the coding unit;
applying, before the core transform, a secondary transform to the transform unit:
decoding a flag specifying whether or not a first index is present;
decoding a secondary index associated with the secondary transform;
decoding the first index associated with the core transform in a case where the secondary index specifies that the secondary transform is not used and in a case where the flag specifies that the first index is present; and
deriving the first index equal to 0 in a case where the secondary index specifies that the secondary transform is used or in a case where the flag specifies that the first index is not present.