Method and device for decoding with palette mode

1. A method for decoding a video sequence of a coded video stream, performed by at least one processor, using at least one color palette in a palette mode, each of the at least one color palette including at least one luma value or at least one chroma value, the method comprising:

determining whether a current tree structure is a dual tree structure where a luma color plane has a split tree structure that is different from a split tree structure of a chroma color plane;

receiving, in a case where the current tree structure is determined to be the dual tree structure, a signal indicating whether a current chroma block is to be decoded using the palette mode;

determining whether the current chroma block is to be decoded using the palette mode based at least on the signal; and

decoding at least one image of the video sequence using one or more color palettes of the at least one color palette based on the determining whether the current tree structure is the dual tree structure,

wherein the decoding comprises decoding, based on determining that the current tree structure is the dual tree structure, the current chroma block using a palette of the at least one color palette in the case where the signal indicates the current chroma block is to be decoded using the palette mode.

2. The method of claim 1 , further comprising:

updating a palette predictor list, the updating comprising:

providing, in a case where the current tree structure is determined to be the dual tree structure, a first luma value of a first palette of the at least one color palette to the palette predictor list and ignoring all chroma values of the first palette, such that no chroma value of the first palette is provided to the palette predictor list, wherein

the decoding the at least one image comprises decoding the at least one image of the video sequence by predicting a second palette of the at least one color palette using the palette predictor list.

3. The method of claim 2 , further comprising:

receiving a palette predictor initializer;

initializing, in the case where the current tree structure is determined to be the dual tree structure, the palette predictor list with a luma value signaled by the palette predictor initializer; and

setting, in the case where the current tree structure is determined to be the dual tree structure, a chroma value of the palette predictor list with a predefined value, without the palette predictor initializer signaling any chroma value to the palette predictor list.

4. The method of claim 1 , further comprising:

receiving, in a case where the luma color plane is to be decoded while the current tree structure is determined to be the dual tree structure, a signal indicating a luma value of an escape pixel without receiving any signal indicating a chroma value of the escape pixel to be used in the palette mode, wherein

the decoding the at least one image comprises using the luma value of the escape pixel in the palette mode.

5. The method of claim 1 , wherein

the signal indicating whether the current chroma block is to be decoded using the palette mode is received based on at least one of co-located luma blocks being in the palette mode.

6. The method of claim 1 , further comprising:

determining whether at least one luma block, co-located to the current chroma block, is using the palette mode; and

determining whether the current chroma block is to be using the palette mode based on the determining whether the at least one luma block is using the palette mode, wherein

the decoding the at least one image comprises decoding the current chroma block using the palette of the at least one color palette in the case where the current chroma block is to be decoded using the palette mode.

7. The method of claim 6 , wherein

the at least one luma block is a plurality of luma blocks co-located to the current chroma block, and

the current chroma block is determined to be using the palette mode based on all of the plurality of luma blocks being determined to be using the palette mode.

8. The method of claim 6 , wherein

the at least one luma block is a plurality of luma blocks co-located to the current chroma block, and

the current chroma block is determined to be using the palette mode based on a number of the plurality of luma blocks, greater than a predetermined threshold, being determined to be using the palette mode.

9. The method of claim 1 , wherein

the at least one image decoded is a part of a video with three color components,

the at least one color palette comprises a respective color palette table for each of the three color components, and

the method further comprises predicting the respective color palettes tables for each of the three color components using a respective palette predictor list for each of the three color components.

10. A non-transitory computer-readable storage medium storing instructions that cause at least one processor to:

determine whether a current tree structure is a dual tree structure where a luma color plane has a split tree structure that is different from a split tree structure of a chroma color plane;

determine whether a current chroma block is to be decoded using a palette mode based on at least a signal that is received, in a case where the current tree structure is determined to be the dual tree structure, and that indicates whether the current chroma block is to be decoded using the palette mode; and

decode at least one image of a video sequence using one or more color palettes of an at least one color palette in the palette mode based on determining whether the current tree structure is the dual tree structure, wherein

the instructions are configured to cause the at least one processor to decode, based on determining that the current tree structure is the dual tree structure, the current chroma block using a palette of the at least one color palette in the case where the signal indicates the current chroma block is to be decoded using the palette mode, and

each of the at least one color palette includes at least one luma value or at least one chroma value.

11. The non-transitory computer-readable storage medium of claim 10 , wherein the instructions further cause the at least one processor to:

update a palette predictor list by providing, in a case where the current tree structure is determined to be the dual tree structure, a first luma value of a first palette of the at least one color palette to the palette predictor list and ignoring all chroma values of the first palette, such that no chroma value of the first palette is provided to the palette predictor list, wherein

the instructions cause the at least one processor to decode the at least one image of the video sequence by predicting a second palette of the at least one color palette using the palette predictor list.

12. A system comprising:

at least one processor; and

memory storing computer code that is for decoding a video sequence of a coded video stream using at least one color palette in a palette mode, each of the at least one color palette including at least one luma value or at least one chroma value, the computer code comprising:

first code configured to cause the at least one processor to determine whether a current tree structure is a dual tree structure where a luma color plane has a split tree structure that is different from a split tree structure of a chroma color plane;

second code configured to cause the at least one processor to determine whether a current chroma block is to be decoded using the palette mode based on at least a signal that is received, in a case where the current tree structure is determined to be the dual tree structure, and that indicates whether the current chroma block is to be decoded using the palette mode; and

third code configured to cause the at least one processor to decode at least one image of the video sequence using one or more color palettes of the at least one color palette in the palette mode based on determining whether the current tree structure is the dual tree structure, wherein

the third code is configured to cause the at least one processor to decode, based on determining that the current tree structure is the dual tree structure, the current chroma block using a palette of the at least one color palette in the case where the signal indicates the current chroma block is to be decoded using the palette mode.

13. The system of claim 12 , wherein the computer code further comprises:

fourth code configured to cause the at least one processor to update a palette predictor list, by providing, in a case where the current tree structure is determined to be the dual tree structure, a first luma value of a first palette of the at least one color palette to the palette predictor list and ignoring all chroma values of the first palette, such that no chroma value of the first palette is provided to the palette predictor list, wherein

the third code is configured cause the at least one processor to decode the at least one image of the video sequence by predicting a second palette of the at least one color palette using the palette predictor list.

14. The system of claim 13 , wherein the computer code further comprises:

fifth code configured to cause the at least one processor to initialize, in the case where the current tree structure is determined to be the dual tree structure, the palette predictor list with a luma value signaled by a palette predictor initializer that is received; and

sixth code configured to cause the at least one processor to set, in the case where the current tree structure is determined to be the dual tree structure, a chroma value of the palette predictor list with a predefined value, without the palette predictor initializer signaling any chroma value to the palette predictor list.

15. The system of claim 12 , wherein

the third code is configured cause the at least one processor to decode the at least one image using a luma value of an escape pixel in the palette mode that is indicated by a signaled received, in a case where the luma color plane is to be decoded while the current tree structure is determined to be the dual tree structure and without receiving any signal indicating a chroma value of the escape pixel to be used in the palette mode.

16. The system of claim 12 , wherein

the signal indicating whether the current chroma block is to be decoded using the palette mode is received based on at least one of co-located luma blocks being in the palette mode.

17. The system of claim 12 , wherein the computer code further comprises:

fourth code configured to cause the at least one processor to determine whether at least one luma block, co-located to the current chroma block, is using the palette mode; and

fifth code configured to cause the at least one processor to determine whether the current chroma block is to be using the palette mode based on the determining whether the at least one luma block is using the palette mode, wherein

the third code is configured to cause the at least one processor to decode the current chroma block using the palette of the at least one color palette in the case where the current chroma block is to be decoded using the palette mode.

18. The system of claim 17 , wherein

the at least one luma block is a plurality of luma blocks co-located to the current chroma block, and

the fifth code is configured to cause the at least one processor to determine the current chroma block to be using the palette mode based on all of the plurality of luma blocks being determined to be using the palette mode.

19. The system of claim 17 , wherein

the at least one luma block is a plurality of luma blocks co-located to the current chroma block, and

the fifth code is configured to cause the at least one processor to determine the current chroma block to be using the palette mode based on a number of the plurality of luma blocks, greater than a predetermined threshold, being determined to be using the palette mode.

20. The system of claim 12 , wherein

the at least one image decoded is a part of a video with three color components,

the at least one color palette comprises a respective color palette table for each of the three color components, and

the computer code further comprises fourth code that is configured to cause the at least one processor to predict the respective color palettes tables for each of the three color components using a respective palette predictor list for each of the three color components.