Method and apparatus for point cloud coding

1. A method of point cloud geometry decoding in a point cloud decoder, comprising:

receiving, from a coded bitstream for a point cloud that includes a set of points, chroma prediction residual information of a point in the set of points, the chroma prediction residual information including a Cb component and a Cr component;

determining, by processing circuitry and from the coded bitstream for the point cloud, a type of correlation from among a plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information; and

decoding the chroma prediction residual information based on the determined type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information.

2. The method of claim 1 , wherein the decoding comprises:

decoding the Cb component of the chroma prediction residual information and the Cb component minus the Cr component of the chroma prediction residual information based on the determined type of the correlation from among the plurality of correlation types between the Cb component and the Cr component being positive.

3. The method of claim 1 , wherein the decoding comprises:

decoding the Cb component of the chroma prediction residual information and the Cb component plus the Cr component of the chroma prediction residual information based on the determined type of the correlation from among the plurality of correlation types between the Cb component and the Cr component being negative.

4. The method of claim 1 , wherein the decoding comprises:

decoding the Cb component of the chroma prediction residual information and the Cr component of the chroma prediction residual information based on no indicated correlation between the Cb component and the Cr component.

5. The method of claim 1 , wherein the determining comprises:

determining the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is positive based on a first number of residual points from one of a coded region, a previous level of detail (LOD), or N nearest-neighboring points of the point being positively correlated; and

determining the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is negative based on a second number of residual points from the one of the coded region, the previous LOD, or the N nearest-neighboring points of the point being negatively correlated.

6. The method of claim 5 , wherein the coded region comprises at least one of a frame, a video sequence, a group of pictures (GOP), a picture, a slice, or a tile.

7. The method of claim 5 , wherein the N is a positive integer that is equal to 3 or 4.

8. The method of claim 1 , wherein

the coded bitstream includes signaling information that is indicative of the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information,

the signaling information indicating the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is positive based on a first number of residual points from one of a coded region, a previous level of detail (LOD), a LOD to which the point belongs, and N nearest-neighboring points of the point being positively correlated, and

the signaling information indicating the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is negative based on a second number of residual points from the one of the coded region, the previous LOD. the LOD to which the point belongs, and the N nearest-neighboring points of the point being negatively correlated.

9. A method of point cloud geometry decoding in a point cloud decoder, comprising:

receiving, from a coded bitstream for a point cloud that includes a set of points, first signaling information that indicates first chroma prediction residual information and second chroma prediction residual information of a point in the set of points is decoded based on a type of correlation from among a plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information, the coded bitstream including the first chroma prediction residual information and the second chroma prediction residual information;

determining the type of the correlation from among the plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information based on the first signaling information; and

reconstructing first chroma information and second chroma information based on the first chroma prediction residual information, the second chroma prediction residual information, and the determined type of the correlation from among the plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information.

10. The method of claim 9 , wherein the determining further comprises:

determining second signaling information based on the first signaling information being a first value, the second signaling information indicating that the type of the correlation from among the plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information is indicated by third signaling information;

determining the third signaling information based on the second signaling information being the first value, the third signaling information indicating the type of the correlation from among the plurality of correlation types between the first chroma prediction residual nation and the second chroma prediction residual information; and

determining the type of the correlation from among the plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information based on the third signaling information.

11. The method of claim 10 , wherein the determining the type of the correlation further comprises:

determining the type of the correlation from among the plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information is negative based on the third signaling information being the first value; and

determining the type of the correlation from among the plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information is positive based on the third signaling information being a second value.

12. The method of claim 9 , wherein the reconstructing further comprises:

reconstructing the first chroma information by performing a first inverse-quantization process on the first chroma prediction residual information; and

in response to the first signaling information being a first value, reconstructing the second chroma information that includes a first portion and a second portion, wherein:

the first portion is obtained by performing a second inverse-quantization process on the second chroma prediction residual information, and

the second portion is obtained by multiplying the reconstructed first chroma information and the type of the correlation from among the plurality of correlation types between the first chroma prediction residual information and the second chroma prediction residual information.

13. The method of claim 9 , wherein the reconstructing further comprises:

reconstructing the first chroma information by performing a first inverse-quantization process on the first chroma prediction residual information; and

in response to the first signaling information being a second value, reconstructing the second chroma information by performing a second inverse-quantization process on the second chroma prediction residual information.

14. The method of claim 8 , wherein the first chroma prediction residual information and the second chroma prediction residual information are correlated in a first order relation with zero offsets.

15. An apparatus of processing point cloud data, comprising:

processing circuitry configured to:

receive, from a coded bitstream for a point cloud that includes a set of points, chroma prediction residual information of a point in the set of points, the chroma prediction residual information including a Cb component and a Cr component;

determine, from the coded bitstream for the point cloud, a type of correlation from among a plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information; and

decode the chroma prediction residual information based on the determined type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information.

16. The apparatus of claim 15 , wherein the processing circuitry is further configured to:

decode the Cb component of the chroma prediction residual information and the Cb component minus the Cr component of the chroma prediction residual information based on the determined type of the correlation from among the plurality of correlation types between the Cb component and the Cr component being positive.

17. The apparatus of claim 15 , wherein the processing circuitry is further configured to:

decode the Cb component of the chroma prediction residual information and the Cb component plus the Cr component of the chroma prediction residual information based on the determined type of the correlation from among the plurality of correlation types between the Cb component and the Cr component being negative.

18. The apparatus of claim 15 , wherein the processing circuitry is further configured to:

decode the Cb component of the chroma prediction residual information and the Cr component of the chroma prediction residual information based on no indicated correlation between the Cb component and the Cr component.

19. The apparatus of claim 15 , wherein the processing circuitry is further configured to:

determined the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is positive based on a first number of residual points from one of a coded region, a previous level of detail (LOD), or N nearest-neighboring points of the point being positively correlated; and

determine the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is negative based on a second number of residual points from the one of the coded region, the previous LOD, or the N nearest-neighboring points of the point being negatively correlated.

20. The apparatus of claim 15 , wherein

the coded bitstream includes signaling information that is indicative of the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information,

the signaling information indicating the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is positive based on a first number of residual points from one of a coded region, a previous level of detail (LOD), a LOD to which the point belongs, and N nearest-neighboring points of the point being positively correlated, and

the signaling information indicating the type of the correlation from among the plurality of correlation types between the Cb component and the Cr component of the chroma prediction residual information is negative based on a second number of residual points from the one of the coded region, the previous LOD, the LOD to which the point belongs, and the N nearest-neighboring points of the point being negatively correlated.