DIRECTIONAL CROSS COMPONENT FILTER FOR VIDEO CODING

1 . A video decoding method, comprising:

decoding a bitstream associated with one or more pictures, wherein the decoding of the bitstream reconstructs a first luma block and a first chroma block, the first luma block and first chroma block being collocated;

determining a direction of luma samples in the first luma block;

filtering the first chroma block based on the determined direction, to generate a second chroma block;

determining an offset for a chroma sample in the first chroma block along the determined direction, wherein the offset is determined based on the first luma block and the determined direction;

adding the offset to the second chroma block, to generate a third chroma block; and

generating a decoded video frame based on the third chroma block.

2 . The method according to claim 1 , wherein generating the decoded video frame based on the third chroma block comprises:

applying a filter to the third chroma block, to generate a fourth chroma block; and

generating the decoded video frame based on the fourth chroma block.

3 . The method according to claim 2 , wherein the filter is a Wiener filter or a dual self-guided filter.

4 . The method according to claim 1 , wherein determining the offset for the chroma sample in the first chroma block along the determined direction comprises:

determining, for chroma sample in the first chroma block along the determined direction, a collocated luma sample in the first luma block;

determining, in the first luma block, a plurality of neighboring luma samples of the collocated luma sample; and

applying a filter to the plurality of neighboring luma samples, to determine the offset.

5 . The method according to claim 4 , wherein the plurality of neighboring luma samples forms a cross shape.

6 . The method according to claim 4 , wherein applying the filter to the plurality of neighboring luma samples comprises:

decoding a set of filter coefficients from the bitstream, the set of filter coefficients being associated with the determined direction; and

applying the set of filter coefficients to the plurality of neighboring luma samples, to determine the offset.

7 . The method according to claim 4 , wherein the filter is an 8-tap filter.

8 . The method according to claim 1 , wherein filtering the reconstructed luma block and reconstructed chroma block based on the direction comprises:

selecting a set of filter coefficients based on the direction; and

applying the selected set of filter coefficients to the reconstructed luma block and reconstructed chroma block.

9 . The method according to claim 1 , wherein the chroma sample in the first chroma block along the determined direction is a Cb sample or a Cr sample.

10 . A video encoding method, comprising:

encoding an input video frame;

reconstructing a luma block and a chroma block based on the encoded video frame, the reconstructed luma and chroma blocks being collocated;

determining a direction of luma samples in the reconstructed luma block;

determining a set of filter coefficients for a chroma sample in the reconstructed chroma block along the determined direction, wherein the set of filter coefficients is determined based on the input video frame and the reconstructed luma block; and

encoding the set of filter coefficients into a bitstream.

11 . The method according to claim 10 , wherein determining the set of filter coefficients for the chroma sample in the reconstructed chroma block along the determined direction comprises:

determining, for chroma sample in the reconstructed chroma block along the determined direction, a collocated luma sample in the reconstructed luma block;

determining, in the reconstructed luma block, a plurality of neighboring luma samples of the collocated luma sample; and

determining the set of filter coefficients based on the input video frame and the plurality of neighboring luma samples.

12 . The method according to claim 11 , wherein the plurality of neighboring luma samples forms a cross shape.

13 . The method according to claim 11 , wherein the plurality of neighboring luma samples comprises 8 neighboring luma samples of the collocated luma sample.

14 . The method according to claim 10 , wherein determining the set of filter coefficients for the chroma sample in the reconstructed chroma block along the determined direction comprises:

determining a difference between the input video frame and the chroma sample in the reconstructed chroma block along the determined direction; and

determining the set of filter coefficients based on the difference.

15 . The method according to claim 10 , wherein the chroma sample in the reconstructed chroma block along the determined direction is a Cb sample or a Cr sample.

16 . A method of storing a bitstream of a video, the method comprising:

reconstructing, based on an input video frame, a luma block and a chroma block, the reconstructed luma and chroma blocks being collocated;

determining a direction of luma samples in the reconstructed luma block;

determining a set of filter coefficients for a chroma sample in the reconstructed chroma block along the determined direction, wherein the set of filter coefficients is determined based on the input video frame and the reconstructed luma block;

generating a bitstream comprising the set of filter coefficients; and

storing the bitstream in a non-transitory computer readable medium.

17 . The method according to claim 16 , wherein determining the set of filter coefficients for the chroma sample in the reconstructed chroma block along the determined direction comprises:

determining, for chroma sample in the reconstructed chroma block along the determined direction, a collocated luma sample in the reconstructed luma block;

determining, in the reconstructed luma block, a plurality of neighboring luma samples of the collocated luma sample; and

determining the set of filter coefficients based on the input video frame and the plurality of neighboring luma samples.

18 . The method according to claim 17 , wherein the plurality of neighboring luma samples forms a cross shape.

19 . The method according to claim 17 , wherein the plurality of neighboring luma samples comprises 8 neighboring luma samples of the collocated luma sample.

20 . The method according to claim 16 , wherein determining the set of filter coefficients for the chroma sample in the reconstructed chroma block along the determined direction comprises:

determining a difference between the input video frame and the chroma sample in the reconstructed chroma block along the determined direction; and

determining the set of filter coefficients based on the difference.