Illumination compensation for video encoding and decoding

1 . A method for a video decoder, the method comprising:

determining that a sub-block based motion compensation mode is used for a first block of picture information;

enabling illumination compensation for decoding the first block based on a plurality of motion vectors associated with respective ones of a plurality of sub-blocks of the first block of picture information meeting a similarity criterion, wherein the similarity criterion comprises at least the plurality of motion vectors having a magnitude relationship that comprises a standard deviation of each component of the plurality of motion vectors being less than a value;

determining that a second block of picture information spatially neighboring the first block is decoded based on an illumination compensation; and

based on determining that the second block of picture information spatially neighboring the first block was decoded based on the illumination compensation, decoding the first block based on the sub-block based motion compensation mode and the illumination compensation.

2 . A method for a video encoder, the method comprising:

determining that a sub-block based motion compensation mode is used for a first block of picture information;

enabling illumination compensation for encoding the first block based on a plurality of motion vectors associated with respective ones of a plurality of sub-blocks of the first block of picture information meeting a similarity criterion, wherein the similarity criterion comprises at least the plurality of motion vectors having a magnitude relationship that comprises a standard deviation of each component of the plurality of motion vectors being less than a value;

determining that a second block of picture information spatially neighboring the first block is encoded based on an illumination compensation; and

based on determining that the second block of picture information spatially neighboring the first block was encoded based on the illumination compensation, encoding the first block based on the sub-block based motion compensation mode and the illumination compensation.

3 . A video decoding device comprising:

a processor configured to:

determine that a sub-block based motion compensation mode is used for a first block of picture information;

enable illumination compensation for decoding the first block based on a plurality of motion vectors associated with respective ones of a plurality of sub-blocks of the first block of picture information meeting a similarity criterion, wherein the similarity criterion comprises at least the plurality of motion vectors having a magnitude relationship that comprises a standard deviation of each component of the plurality of motion vectors being less than a value;

determine that a second block of picture information spatially neighboring the first block is decoded based on an illumination compensation; and

based on determining that the second block of picture information spatially neighboring the first block was decoded based on the illumination compensation, decode the first block based on the sub-block based motion compensation mode and the illumination compensation.

4 . A video encoding device comprising:

a processor configured to:

determine that a sub-block based motion compensation mode is used for a first block of picture information;

enable illumination compensation for encoding the first block based on a plurality of motion vectors associated with respective ones of a plurality of sub-blocks of the first block of picture information meeting a similarity criterion, wherein the similarity criterion comprises at least the plurality of motion vectors having a magnitude relationship that comprises a standard deviation of each component of the plurality of motion vectors being less than a value;

determine that a second block of picture information spatially neighboring the first block was encoded based on an illumination compensation; and

based on determining that the second block of picture information spatially neighboring the first block was encoded based on the illumination compensation, encode the first block based on the sub-block based motion compensation mode and the illumination compensation.

5 . The method of claim 1 , wherein the sub-block based motion compensation mode comprises a sub-block based temporal motion vector prediction mode.

6 . The method of claim 1 , wherein the plurality of sub-blocks comprises the sub-blocks of the first block of picture information and the plurality of motion vectors comprises the motion vectors of the sub-blocks of the first block of picture information.

7 . The method of claim 1 , wherein the similarity criterion further comprises at least one of:

the plurality of motion vectors having the same reference picture or reference pictures; or

the plurality of motion vectors having the same direction.

8 . The method of claim 7 , wherein the plurality of motion vectors having the same direction comprises any of the plurality of motion vectors being unidirectional with the same reference index or being bidirectional with the same reference indices.

9 . The method of claim 1 , wherein the value comprises five samples.

10 . The method of claim 1 , wherein the similarity criterion comprises a maximum value of a difference between a maximum and a minimum of each vector component of each of the plurality of motion vectors.

11 . The method of claim 10 , wherein the maximum value of the difference between the maximum and the minimum of each vector component of each of the plurality of motion vectors comprises a greater difference among a difference for an x-component for each of the plurality of motion vectors and a difference for a y-component for each of the plurality of motion vectors.

12 . The method of claim 1 , wherein the similarity criterion comprises an average difference between a first motion vector in a scan order and each sub-block motion vector.

13 . The method of claim 12 , wherein the average difference between the first motion vector in the scan order and each sub-block motion vector comprises an average of a sum of x-component differences between each sub-block motion vector and the first motion vector and y-component differences between each sub-block motion vector and the first motion vector.

14 . The method of claim 13 , wherein the first motion vector in the scan order is associated with a top-left sub-block.

15 . The device of claim 3 , wherein the plurality of sub-blocks comprises the sub-blocks of the first block of picture information and the plurality of motion vectors comprises the motion vectors of the sub-blocks of the first block of picture information.

16 . The device of claim 3 , wherein the similarity criterion further comprises at least one of:

the plurality of motion vectors having the same reference picture or reference pictures; or

the plurality of motion vectors having the same direction.

17 . The device of claim 16 , wherein the plurality of motion vectors having the same direction comprises any of the plurality of motion vectors being unidirectional with the same reference index or being bidirectional with the same reference indices.

18 . The device of claim 3 , wherein the value comprises five samples.

19 . The device of claim 3 , wherein the similarity criterion comprises a maximum value of a difference between a maximum and a minimum of each vector component of each of the plurality of motion vectors.

20 . The device of claim 19 , wherein the maximum value of the difference between the maximum and the minimum of each vector component of each of the plurality of motion vectors comprises a greater difference among a difference for an x-component for each of the plurality of motion vectors and a difference for a y-component for each of the plurality of motion vectors.

21 . The device of claim 3 , wherein the similarity criterion comprises an average difference between a first motion vector in a scan order and each sub-block motion vector.

22 . The device of claim 21 , wherein the average difference between the first motion vector in the scan order and each sub-block motion vector comprises an average of a sum of x-component differences between each sub-block motion vector and the first motion vector and y-component differences between each sub-block motion vector and the first motion vector.

23 . The device of claim 22 , wherein the first motion vector in the scan order is associated with a top-left sub-block.