Techniques and apparatus for inter-channel prediction and transform for point-cloud attribute coding

1. A method for coding attribute information of a point cloud, the method performed by at least one processor and comprising:

obtaining the point cloud including a set of points in a three-dimensional space; and

coding the attribute information of at least one point of the point cloud using a YCoCg-R transform as a lossless inloop transform of prediction residuals of the at least one point and based on determining to use the lossless inloop transform of prediction residuals of the at least one point by a conditional check comprising at least one of:

determining whether a number of neighboring points to the at least one point experience any of reduced residual magnitude and reduced residual variance by application of the YCoCg-R transform as the lossless inloop transform of prediction residuals to ones of the neighboring points,

determining a maximum absolute difference in channel values of the neighboring points, and

determining interchannel correlation from the neighboring points.

2. The method of claim 1 , further comprising:

transmitting the point cloud based on coding the attribute information using the YCoCg-R transform.

3. The method of claim 1 , wherein the YCoCg-R transform is used for graph-based point cloud compression (G-PCC).

4. The method of claim 1 , wherein Co=R−B.

5. The method of claim 4 , wherein t=B+(Co>>1).

6. The method of claim 5 , wherein Cg=G−t.

7. The method of claim 6 , wherein Y=t+(Cg>>1).

8. A device for coding attribute information of a point cloud, the device comprising:

at least one memory configured to store program code; and

at least one processor configured to read the program code and operate as instructed by the program code, the program code including:

obtaining code configured to cause the at least one processor to obtain the point cloud including a set of points in a three-dimensional space; and

coding code configured to cause the at least one processor to code the attribute information of at least one point of the point cloud using a YCoCg-R transform as a lossless inloop transform of prediction residuals of the at least one point and based on determining to use the lossless inloop transform of prediction residuals of the at least one point by a conditional check comprising at least one of:

determining whether a number of neighboring points to the at least one point experience any of reduced residual magnitude and reduced residual variance by application of the YCoCg-R transform as the lossless inloop transform of prediction residuals to ones of the neighboring points,

determining a maximum absolute difference in channel values of the neighboring points, and

determining interchannel correlation from the neighboring points.

9. The device of claim 8 , wherein the program code further includes:

transmitting code configured to cause the at least one processor to transmit the point cloud based on coding the attribute information using the YCoCg-R transform.

10. The device of claim 8 , wherein the YCoCg-R transform is used for graph-based point cloud compression (G-PCC).

11. The device of claim 8 , wherein Co=R−B.

12. The device of claim 11 , wherein t=B+(Co>>1).

13. The device of claim 12 , wherein Cg=G−t.

14. The device of claim 13 , wherein Y=t+(Cg>>1).

15. A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more instructions that, when executed by one or more processors of a device for coding attribute information of a point cloud, cause the one or more processors to:

obtain the point cloud including a set of points in a three-dimensional space; and

code the attribute information of at least one point of the point cloud using a YCoCg-R transform as a lossless inloop transform of prediction residuals of the at least one point and based on determining to use the lossless inloop transform of prediction residuals of the at least one point by a conditional check comprising at least one of:

determining whether a number of neighboring points to the at least one point experience any of reduced residual magnitude and reduced residual variance by application of the YCoCg-R transform as the lossless inloop transform of prediction residuals to ones of the neighboring points,

determining a maximum absolute difference in channel values of the neighboring points, and

determining interchannel correlation from the neighboring points.

16. The non-transitory computer-readable medium of claim 15 , wherein the one or more instructions further cause the one or more processors to transmit the point cloud based on coding the attribute information using the YCoCg-R transform.

17. The non-transitory computer-readable medium of claim 15 , wherein Co=R−B.

18. The non-transitory computer-readable medium of claim 17 , wherein t=B+(Co>>1).

19. The non-transitory computer-readable medium of claim 18 , wherein Cg=G−t.

20. The non-transitory computer-readable medium of claim 19 , wherein Y=t+(Cg>>1).