Decoding device, encoding device, bitstream generation device, decoding method, and encoding method

WO2026133952A1PCT designated stage Publication Date: 2026-06-25PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA
Filing Date
2025-12-03
Publication Date
2026-06-25

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    Figure JP2025042094_25062026_PF_FP_ABST
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Abstract

A decoding device (200) comprises a circuit (b1) and a memory (b2) which is connected to the circuit (b1), wherein the circuit (b1) selects an intra prediction mode from among a plurality of intra prediction modes (S601), the plurality of intra prediction modes include a regular intra prediction mode and one or more decoder derivation intra prediction modes, the selected intra prediction mode is used to generate a prediction image for a block to be processed (S602), a first prediction method and a second prediction method are selectable when the regular intra prediction mode is selected, and when a first mode among the one or more decoder derivation intra prediction modes is selected, the first prediction method is unselectable, and the second prediction method is selectable.
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Claims

1. A decoding device comprising a circuit and a memory connected to the circuit, wherein the circuit, in operation, selects an intra-prediction mode from a plurality of intra-prediction modes, the plurality of intra-prediction modes include a regular intra-prediction mode that decodes information regarding the prediction direction for a block to be processed from a bitstream, and one or more decoder-derived intra-prediction modes that do not decode the information regarding the prediction direction from the bitstream, generates a predicted image of the block to be processed using the selected intra-prediction mode, when the regular intra-prediction mode is selected, in generating the predicted image, a first prediction method that generates the predicted image by matrix operation between a matrix and a first reference pixel set and a second prediction method that generates the predicted image from a second reference pixel set based on the prediction direction are selectable, and when a first mode that derives the prediction direction using the gradient of pixel values ​​around the block to be processed is selected from the one or more decoder-derived intra-prediction modes, in generating the predicted image, the first prediction method is not selectable, but the second prediction method is selectable.

2. The decoding device according to claim 1, wherein when the regular intra prediction mode is selected, a prediction method is selected from a plurality of prediction methods, including the first prediction method and the second prediction method, based on information regarding the prediction direction.

3. The decoding device according to claim 1 or 2, wherein, among the one or more decoder derivation intra-prediction modes, a second mode is selected in which the prediction direction for the processing target block is derived using the frequency of occurrence of the prediction direction used for intra-prediction around the processing target block, and in the generation of the prediction image, the first prediction method is not selectable, and the second prediction method is selectable.

4. The decoding device according to claim 1 or 2, wherein, among the one or more decoder derivation intra-prediction modes, a second mode is selected in which the prediction direction for the processing target block is derived using the frequency of occurrence of the prediction direction used for intra-prediction around the processing target block, and in the generation of the prediction image, the first prediction method and the second prediction method are selectable.

5. The decoding device according to claim 1 or 2, wherein, among the one or more decoder derivation intra-prediction modes, a third mode is selected in which the prediction direction is derived using a cost calculated by applying intra-prediction to a template around the processing target block, the first prediction method is not selectable and the second prediction method is selectable in the generation of the predicted image.

6. The decoding device according to claim 1 or 2, wherein, among the one or more decoder derivation intra-prediction modes, a third mode is selected in which the prediction direction is derived using a cost calculated by applying intra-prediction to a template around the processing target block, and in the generation of the predicted image, the first prediction method and the second prediction method are selectable.

7. The decoding device according to claim 1 or 2, wherein, among the one or more decoder derivation intra-prediction modes, a fourth mode is selected in which the prediction direction is derived without evaluating the first prediction method and the second prediction method, and in the generation of the predicted image, the first prediction method is not selectable and the second prediction method is selectable.

8. Encoding device comprising a circuit and a memory connected to the circuit, wherein the circuit, in operation, selects an intra-prediction mode from a plurality of intra-prediction modes, the plurality of intra-prediction modes include a regular intra-prediction mode that encodes information regarding the prediction direction for a block to be processed into a bitstream, and one or more decoder-derived intra-prediction modes that do not encode information regarding the prediction direction into the bitstream, generates a predicted image of the block to be processed using the selected intra-prediction mode, when the regular intra-prediction mode is selected, in generating the predicted image, a first prediction method that generates the predicted image by matrix operation between a matrix and a first reference pixel set and a second prediction method that generates the predicted image from a second reference pixel set based on the prediction direction are selectable, and when a first mode that derives the prediction direction using the gradient of pixel values ​​around the block to be processed is selected from the one or more decoder-derived intra-prediction modes, in generating the predicted image, the first prediction method is not selectable and the second prediction method is selectable.

9. The encoding device according to claim 8, wherein the circuit selects an intra prediction mode from a plurality of intra prediction modes based on a cost value derived from the predicted image and the input image of the block to be processed, and if the regular intra prediction mode is selected, it evaluates the first prediction method associated with the first prediction direction and the second prediction method associated with a second prediction direction in the vicinity of the first prediction direction to derive the prediction direction.

10. A circuit and a memory connected to the circuit, wherein the circuit, in operation, selects an intra-prediction mode from a plurality of intra-prediction modes, the plurality of intra-prediction modes include a regular intra-prediction mode that encodes information regarding the prediction direction for a block to be processed into a bitstream, and one or more decoder-derived intra-prediction modes that do not encode information regarding the prediction direction into the bitstream, generates a predicted image of the block to be processed using the selected intra-prediction mode, generates the bitstream by encoding the block to be processed into a bitstream using the predicted image, when the regular intra-prediction mode is selected, in generating the predicted image, a first prediction method that generates the predicted image by matrix operation between a matrix and a first reference pixel set and a second prediction method that generates the predicted image from a second reference pixel set based on the prediction direction are selectable, when a first mode that derives the prediction direction using the gradient of pixel values ​​around the block to be processed is selected from the one or more decoder-derived intra-prediction modes, in generating the predicted image, the first prediction method is not selectable, and the second prediction method is selectable. Bitstream generator.

11. A decoding method comprising: selecting an intra-prediction mode from a plurality of intra-prediction modes, wherein the plurality of intra-prediction modes include a regular intra-prediction mode that decodes information regarding the prediction direction for a block to be processed from a bitstream, and one or more decoder-derived intra-prediction modes that do not decode the information regarding the prediction direction from the bitstream; generating a predicted image of the block to be processed using the selected intra-prediction mode; when the regular intra-prediction mode is selected, a first prediction method that generates the predicted image by matrix operations between a matrix and a first reference pixel set, and a second prediction method that generates the predicted image from a second reference pixel set based on the prediction direction, are selectable in the generation of the predicted image; when the first mode among the one or more decoder-derived intra-prediction modes that derives the prediction direction using the gradient of pixel values ​​around the block to be processed is selected, the first prediction method is not selectable, and the second prediction method is selectable in the generation of the predicted image.

12. An encoding method for selecting an intra-prediction mode from a plurality of intra-prediction modes, wherein the plurality of intra-prediction modes include a regular intra-prediction mode that encodes information regarding the prediction direction for a block to be processed into a bitstream, and one or more decoder-derived intra-prediction modes that do not encode information regarding the prediction direction into the bitstream, and for generating a predicted image of the block to be processed using the selected intra-prediction mode, wherein when the regular intra-prediction mode is selected, in generating the predicted image, a first prediction method that generates the predicted image by matrix operations between a matrix and a first reference pixel set, and a second prediction method that generates the predicted image from a second reference pixel set based on the prediction direction are selectable, and when a first mode that derives the prediction direction using the gradient of pixel values ​​around the block to be processed is selected from the one or more decoder-derived intra-prediction modes, the first prediction method is not selectable, but the second prediction method is selectable in generating the predicted image.