Image encoding/decoding, method for an inter-component prediction of a chroma block
An image encoding/decoding method and apparatus for performing intra prediction mode based intra prediction are provided. An image decoding method may comprise decoding an intra prediction mode of a current block, deriving at least one intra prediction mode from the decoded intra prediction mode of the current block, generating two or more intra prediction blocks using the intra prediction mode of the current block and the derived intra prediction mode, and generating an intra prediction block of the current block based on the two or more intra prediction blocks.
1. An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
determining whether an inter-component prediction mode is applicable to a current chroma block;
deriving information related to whether one of inter-component prediction modes is applied to the current chroma block, based on the inter-component prediction mode being applicable to the current chroma block;
deriving an intra prediction mode of the current chroma block based on index information indicating one of the inter-component prediction modes;
deriving at least one luma reference sample line neighboring a current luma block corresponding to the current chroma block and a chroma reference sample line adjacent to the current chroma block for inter-component prediction of the current chroma block;
down-sampling luma samples of the current luma block;
deriving prediction parameters for inter-component prediction based on the intra prediction mode; and
deriving prediction samples for the current chroma block based on the down-sampled luma samples and the prediction parameters,
wherein whether the inter-component prediction mode is applicable to the current chroma block is determined based on a size of the current chroma block, a partition depth of the current chroma block and a shape of the current chroma block.
2. The image decoding method of claim 1 , wherein the determining whether the inter-component prediction mode is applicable to the current chroma block comprises determining whether the size of the current chroma block is a predetermined size.
3. The image decoding method of claim 1 , wherein the index information indicates any one of an LA mode that uses left neighboring samples and upper neighboring samples for the inter-component prediction, an L mode that uses the left neighboring samples for the inter-component prediction, and an A mode that uses the upper neighboring samples for the inter-component prediction.
4. The image decoding method of claim 1 , wherein one of the inter-component prediction modes is derived based on the index information and a preset lookup table.
5. The image decoding method of claim 1 , further comprises deriving flag information related to whether the inter-component prediction mode is enabled to the current chroma block.
6. An image encoding method performed by an image encoding apparatus, the image encoding method comprising:
determining whether an inter-component prediction mode is applicable to a current chroma block;
deriving one of the inter-component prediction modes as an intra prediction mode of the current chroma block, based on the inter-component prediction mode being applicable to the current chroma block;
deriving at least one luma reference sample line neighboring a current luma block corresponding to the current chroma block and a chroma reference sample line adjacent to the current chroma block for inter-component prediction of the current chroma block;
down-sampling luma samples of the current luma block;
deriving prediction parameters for inter-component prediction based on the intra prediction mode;
deriving prediction samples for the current chroma block based on the down-sampled luma samples and the prediction parameters, and
encoding image information including information related to whether one of the inter-component prediction modes is applied to the current chroma block and index information indicating one of the inter-component prediction modes,
wherein whether the inter-component prediction mode is applicable to the current chroma block is determined based on a size of the current chroma block, a partition depth of the current chroma block and a shape of the current chroma block.
7. The image encoding method of claim 6 , wherein the determining whether the inter-component prediction mode is applicable to the current chroma block comprises determining whether the size of the current chroma block is a predetermined size.
8. The image encoding method of claim 6 , wherein the index information indicates any one of an LA mode that uses left neighboring samples and upper neighboring samples for the inter-component prediction, an L mode that uses the left neighboring samples for the inter-component prediction, and an A mode that uses the upper neighboring samples for the inter-component prediction.
9. The image encoding method of claim 6 , wherein the encoding image information further comprises deriving flag information related to whether the inter-component prediction mode is enabled to the current chroma block.
10. A transmitting method for image data, the method comprising:
obtaining a bitstream of encoded image information, wherein the encoded image information is generated based on determining whether an inter-component prediction mode is applicable to a current chroma block, deriving one of the inter-component prediction modes as an intra prediction mode of the current chroma block, based on the inter-component prediction mode being applicable to the current chroma block, deriving at least one luma reference sample line neighboring a current luma block corresponding to the current chroma block and a chroma reference sample line adjacent to the current chroma block for inter-component prediction of the current chroma block, down-sampling luma samples of the current luma block, deriving prediction parameters for inter-component prediction based on the intra prediction mode, deriving prediction samples for the current chroma block based on the down-sampled luma samples and the prediction parameters, and encoding image information including information related to whether one of the inter-component prediction modes is applied to the current chroma block and index information indicating one of the inter-component prediction modes, and
transmitting the image data comprising the bitstream,
wherein whether the inter-component prediction mode is applicable to the current chroma block is determined based on a size of the current chroma block, a partition depth of the current chroma block and a shape of the current chroma block.
11. The transmitting method of claim 10 , wherein the determining whether the inter-component prediction mode is applicable to the current chroma block comprises determining whether the size of the current chroma block is a predetermined size.
12. The transmitting method of claim 10 , wherein the index information indicates any one of an LA mode that uses left neighboring samples and upper neighboring samples for the inter-component prediction, an L mode that uses the left neighboring samples for the inter-component prediction, and an A mode that uses the upper neighboring samples for the inter-component prediction.