Parallel processing method for color component of video signal, and device therefor

1. A method for decoding images based on an intra prediction mode, the method comprising:

parsing, by a processor, a first syntax element indicating a composition of components of bitstream data, the composition of components being one of a first structure in which sequential component data comprises each coding tree unit and a second structure in which same component data comprises coding tree units in a unit of specific regions, the component data being one of luma data or chroma data;

parsing, by the processor, information related to entry points for respective component data;

accessing, by the processor, the component data within the bitstream data based on the first syntax element and the information related to the entry points;

parsing, by the processor, a second syntax element indicating whether a CCLM (cross-component linear model) intra prediction on a current chroma block is disabled or not;

deriving, by the processor, an intra prediction mode applied to the current chroma block; and

generating, by the processor, a prediction sample for the current chroma block based on the intra prediction mode,

wherein, when the CCLM intra prediction is disabled, the intra prediction mode is derived in a predetermined first prediction mode set,

when the CCLM intra prediction is not disabled, the intra prediction mode is derived in a predetermined second prediction mode set, and

the second prediction mode set includes intra prediction modes included in the first prediction mode set and the CCLM intra prediction mode.

2. The method of claim 1 , wherein, when the intra prediction mode is the CCLM intra prediction mode, the generating of a prediction sample comprises:

deriving, by the processor, a parameter used for the CCLM intra prediction by using a neighboring sample of a luma block corresponding to the current chroma block and a neighboring sample of the current chroma block; and

generating, by the processor, a prediction sample for the current chroma block by using the parameter and a reconstructed sample of the luma block.

3. The method of claim 1 , wherein the second syntax element is transmitted from an encoder in a unit of a picture, a slice, a tile, or a tile group.

4. The method of claim 1 , wherein, when the CCLM intra prediction is disabled, the current chroma block is decoded with reference to data of a previously parsed luma block.

5. The method of claim 1 , wherein, when the CCLM intra prediction is disabled, the current chroma block is decoded with reference to a residual signal of a previously parsed luma block and an intra prediction mode for the previously parsed luma block.

6. The method of claim 1 , wherein the information related to the entry points comprises a number of the entry points, and at least one of an offset or a bitlength indicating a position of corresponding component data.

7. The method of claim 1 , further comprising:

parsing, by the processor, a first flag indicating whether an entropy initialization for the component data is performed or not; and

performing, by the processor, parallel processing for entropy decoding on each component data based on the first flag.

8. The method of claim 7 , further comprising:

parsing, by the processor, a second flag indicating whether corresponding component data is collected or not; and

collecting, by the processor, the corresponding component data without applying the entropy initialization based on the second flag and performing the entropy decoding based on accumulated probability.

9. A method for encoding images based on an intra prediction mode, comprising:

generating, by a processor, a first syntax element indicating a composition of components of bitstream data, the composition of components being one of a first structure in which sequential component data comprises each coding tree unit and a second structure in which same component data comprises coding tree units in a unit of specific regions, the component data being one of luma data or chroma data;

generating, by the processor, information related to entry points for respective component data;

generating, by the processor, a prediction sample for a current chroma block based on an intra prediction mode;

generating, by the processor, a residual sample for the current chroma block based on the prediction sample for the current chroma block; and

generating, by the processor, a second syntax element indicating whether a cross-component linear model (CCLM) intra prediction on the current chroma block is disabled or not,

wherein, when the intra prediction mode is determined from a predetermined first prediction mode set, the CCLM intra prediction is disabled,

when the intra prediction mode is determined from a predetermined second prediction mode set, the CCLM intra prediction is not disabled, and

the second prediction mode set includes intra prediction modes included in the first prediction mode set and the CCLM intra prediction mode.

10. The method of claim 9 , wherein the second syntax element is transmitted from an encoder in a unit of a picture, a slice, a tile, or a tile group.

11. The method of claim 9 , wherein, when the CCLM intra prediction is disabled, the current chroma block is encoded with reference to data of a previously constructed luma block.

12. The method of claim 9 , wherein, when the CCLM intra prediction is disabled, the current chroma block is encoded with reference to a residual signal of a previously constructed luma block and an intra prediction mode for the previously constructed luma block.

13. The method of claim 9 , wherein the information related to the entry points comprises a number of the entry points, and at least one of an offset or a bitlength indicating a position of corresponding component data.

14. The method of claim 9 , further comprising:

generating, by the processor, a first flag indicating whether an entropy initialization for the component data is performed or not.

15. The method of claim 14 , further comprising:

generating, by the processor, a second flag indicating whether corresponding component data is collected or not.

16. A non-transitory decoder-readable storage medium for storing a bitstream generated based on the method of claim 9 .