Local illumination compensation for video encoding or decoding

Inventors: Philippe Bordes (Laille, FR); Franck Galpin (Thorigne-Fouillard, FR); Fabrice Urban (Thorigne-Fouillard, FR)

Assignee: InterDigital Madison Patent Holdings, SAS

H04N19/52 H04N19/105 H04N19/132 H04N19/139 H04N19/159 H04N19/172 H04N19/176 H04N19/182 H04N19/196

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Quick Facts

Patent No.: US 12713056
App. No.: 18/625,733
Granted: Aug 18, 2026
Kind: B2

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Abstract

Described are methods and apparatuses for encoding/decoding a picture comprising predicting at least one block, wherein the predicting comprises performing motion compensation and local illumination compensation based on a reference block, the local illumination compensation including applying a linear model based on sums of absolute differences of neighboring reconstructed samples and corresponding reference samples of the reference block, wherein the neighboring reconstructed samples and corresponding reference samples of the reference block are co-located according to an L-shape substantially adjacent to the block to be predicted, the L-shape comprising a row of pixels located to the top side of the predicted block and a column of pixels located to the left side of the predicted block, the co-location being determined according a motion vector of the predicted block.

Claims (40)

1 . A method for decoding picture data for at least one block in a picture, the method comprising:

determining a first set of local illumination compensation (LIC) parameters of a first LIC model based on a first set of reconstructed samples in an L-shape associated with the at least one block and a second set of local illumination compensation parameters of a second LIC model based on a second set of reconstructed samples in the L-shape, wherein the first set of reconstructed samples comprises reconstructed samples below a first value and the second set of reconstructed samples comprises reconstructed samples above the first value;

determining a predictor for the at least one block responsive to the determining; and

reconstructing the at least one block based on the predictor.

2 . The method of claim 1 , wherein determining the predictor for the at least one block responsive to the determining comprises disabling local illumination compensation in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters.

3 . The method of claim 1 , wherein determining the predictor for the at least one block responsive to the determining comprises determining a predictor based on a single set of local illumination compensation parameters in a case where a discontinuity greater than a third value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters or in a case where a ratio between a number of samples of the set of reconstructed samples with highest number of samples and a number of samples of the other set of reconstructed samples is greater than a fourth value.

4 . The method of claim 3 , wherein the local illumination compensation parameters of the single set are determined based on an average value of the first set of reconstructed samples and an average value of the second set of reconstructed samples.

5 . The method of claim 1 , wherein in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters, the method comprises correcting the first set of local illumination compensation parameters and the parameters the second set of local illumination compensation parameters based on a value obtained for the first value by the first LIC model and a value obtained for the first value by the second LIC model.

6 . The method of claim 1 , wherein the first value is equal to an average value of the reconstructed samples in the L-shape.

7 . The method of claim 1 , wherein the first value is determined so that a number of reconstructed samples in the first set and a number of reconstructed samples in the second set are substantially the same.

8 . An apparatus for decoding picture data for at least one block in a picture, the apparatus comprising one or more processors and at least one memory coupled to said one or more processors, wherein said one or more processors are configured to perform:

determining a predictor for the at least one block responsive to the determining; and

reconstructing the at least one block based on the predictor.

9 . The apparatus of claim 8 , wherein determining the predictor for the at least one block responsive to the determining comprises disabling local illumination compensation in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters.

10 . The apparatus of claim 8 , wherein determining the predictor for the at least one block responsive to the determining comprises determining a predictor based on a single set of local illumination compensation parameters in a case where a discontinuity greater than a third value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters or in a case where a ratio between a number of samples of the set of reconstructed samples with highest number of samples and a number of samples of the other set of reconstructed samples is greater than a fourth value.

11 . The apparatus of claim 10 , wherein the local illumination compensation parameters of the single set are determined based on an average value of the first set of reconstructed samples and an average value of the second set of reconstructed samples.

12 . The apparatus of claim 8 , wherein in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters, the one or more processors being configured to perform correcting the first set of local illumination compensation parameters and the second set of local illumination compensation parameters based on a value obtained for the first value by the first LIC model and a value obtained for the first value by the second LIC model.

13 . The apparatus of claim 8 , wherein the first value is equal to an average value of the reconstructed samples in the L-shape.

14 . The apparatus of claim 8 , wherein the first value is determined so that a number of reconstructed samples in the first set and a number of reconstructed samples in the second set are substantially the same.

15 . A method for encoding picture data for at least one block in a picture, the method comprising:

determining a predictor for the at least one block responsive to the determining; and

encoding the at least one block based on the predictor.

16 . The method of claim 15 , wherein determining the predictor for the at least one block responsive to the determining comprises disabling local illumination compensation in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters.

17 . The method of claim 15 , wherein determining the predictor for the at least one block responsive to the determining comprises determining a predictor based on a single set of local illumination compensation parameters in a case where a discontinuity greater than a third value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters or in a case where a ratio between a number of samples of the set of reconstructed samples with highest number of samples and a number of samples of the other set of reconstructed samples is greater than a fourth value.

18 . The method of claim 17 , wherein the local illumination compensation parameters of the single set are determined based on an average value of the first set of reconstructed samples and an average value of the second set of reconstructed samples.

19 . The method of claim 15 , wherein in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters, the method comprises correcting the first set of local illumination compensation parameters and the second set of local illumination compensation parameters based on a value obtained for the first value by the first LIC model and a value obtained for the first value by the second LIC model.

20 . The method of claim 15 , wherein the first value is equal to an average value of the reconstructed samples in the L-shape.

21 . The method of claim 15 , wherein the first value is determined so that a number of reconstructed samples in the first set and a number of reconstructed samples in the second set are substantially the same.

22 . An apparatus for encoding picture data for at least one block in a picture, the apparatus comprising one or more processors and at least one memory coupled to said one or more processors, wherein said one or more processors are configured to perform:

determining a predictor for the at least one block responsive to the determining; and

encoding the at least one block based on the predictor.

23 . The apparatus of claim 22 , wherein determining the predictor for the at least one block responsive to the determining comprises disabling local illumination compensation in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters.

24 . The apparatus of claim 22 , wherein determining the predictor for the at least one block responsive to the determining comprises determining a predictor based on a single set of local illumination compensation parameters in a case where a discontinuity greater than a third value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters or in a case where a ratio between a number of samples of the set of reconstructed samples with highest number of samples and a number of samples of the other set of reconstructed samples is greater than a fourth value.

25 . The apparatus of claim 24 , wherein the local illumination compensation parameters of the single set are determined based on an average value of the first set of reconstructed samples and an average value of the second set of reconstructed samples.

26 . The apparatus of claim 22 , wherein in a case where a discontinuity greater than a second value is determined between the first set of local illumination compensation parameters and the second set of local illumination compensation parameters, the one or more processors being configured to perform correcting the first set of local illumination compensation parameters and the second set of local illumination compensation parameters based on a value obtained for the first value by the first LIC model and a value obtained for the first value by the second LIC model.

27 . The apparatus of claim 22 , wherein the first value is equal to an average value of the reconstructed samples in the L-shape.

28 . The apparatus of claim 22 , wherein the first value is determined so that a number of reconstructed samples in the first set and a number of reconstructed samples in the second set are substantially the same.