Signaling color values for 3D lookup table for color gamut scalability in multi-layer video coding

A method of encoding video data, the method comprising:

• generating a three-dimensional (3D) lookup table for color gamut scalability based on a number of octants for each of three color components and color values for each of the octants;
• for each of the octants for each of the color components, encoding color mapping coefficients for a linear color mapping function of the color values in the 3D lookup table used to convert color data in a first color gamut for a lower layer of the video data to a second color gamut for a higher layer of the video data, wherein encoding the color mapping coefficients comprises, for a first one of the octants for each of the color components, encoding at least one coefficient of the color mapping coefficients based on a predicted value of the at least one coefficient of the color mapping coefficients, and wherein the predicted value of the at least one coefficient of the color mapping coefficients is a predefined fixed value;
• predicting video blocks of the video data based on at least one reference picture generated using the 3D lookup table;
• and
• encoding residual data of the video blocks in a bitstream.

A video decoding device comprising:

• a memory configured to store video data;
• and
• one or more processors in communication with the memory and configured to:
• determine a number of octants for each of three color components of a three-dimensional (3D) lookup table for color gamut scalability of the video data,
• for each of the octants for each of the color components, decode color mapping coefficients for a linear color mapping function of color values in the 3D lookup table used to convert color data in a first color gamut for a lower layer of the video data to a second color gamut for a higher layer of the video data, wherein the one or more processors are configured to, for a first one of the octants for each of the color components, decode at least one coefficient of the color mapping coefficients based on a predicted value of the at least one coefficient of the color mapping coefficients, and wherein the predicted value of the at least one coefficient of the color mapping coefficients is a predefined fixed value,
• generate the 3D lookup table based on the number of octants for each of the color components and color values associated with the color mapping coefficients for each of the octants,
• decode residual data of video blocks of the video data, and
• reconstruct the video blocks of the video data based on the decoded residual data and at least one reference picture generated using the 3D lookup table.

A video encoding device comprising:

• a memory configured to store video data;
• and
• one or more processors in communication with the memory and configured to:
• generate a three-dimensional (3D) lookup table for color gamut scalability of the video data based on a number of octants for each of three color components and color values for each of the octants,
• for each of the octants for each of the color components, encode color mapping coefficients for a linear color mapping function of the color values in the 3D lookup table used to convert color data in a first color gamut for a lower layer of the video data to a second color gamut for a higher layer of the video data, wherein the one or more processors are configured to, for a first one of the octants for each of the color components, encode at least one coefficient of the color mapping coefficients based on a predicted value of the at least one coefficient of the color mapping coefficients, and wherein the predicted value of the at least one coefficient of the color mapping coefficients is a predefined fixed value,
• predict video blocks of the video data based on at least one reference picture generated using the 3D lookup table, and
• encode residual data of the video blocks in a bitstream.

A video decoding device comprising:

• means for determining a number of octants for each of three color components of a three-dimensional (3D) lookup table for color gamut scalability;
• means for decoding, for each of the octants for each of the color components, color mapping coefficients for a linear color mapping function of color values in the 3D lookup table used to convert color data in a first color gamut for a lower layer of the video data to a second color gamut for a higher layer of the video data, wherein the means for decoding the color mapping coefficients comprises means for decoding, for a first one of the octants for each of the color components, at least one coefficient of the color mapping coefficients based on a predicted value of the at least one coefficient of the color mapping coefficients, and wherein the predicted value of the at least one coefficient of the color mapping coefficients is a predefined fixed value;
• means for generating the 3D lookup table based on the number of octants for each of the color components and color values associated with the color mapping coefficients for each of the octants;
• means for decoding residual data of video blocks of the video data;
• and
• means for reconstructing the video blocks of the video data based on the decoded residual data and at least one reference picture generated using the 3D lookup table.

A non-transitory computer-readable storage medium storing instructions for decoding video data that, when executed, cause one or more processors to:

• determine a number of octants for each of three color components of a three-dimensional (3D) lookup table for color gamut scalability;
• for each of the octants for each of the color components, decode color mapping coefficients for a linear color mapping function of color values in the 3D lookup table used to convert color data in a first color gamut for a lower layer of the video data to a second color gamut for a higher layer of the video data, wherein the instructions that cause the processor to decode the color mapping coefficients comprise instructions that cause the processor to, for a first one of the octants for each of the color components, decode at least one coefficient of the color mapping coefficients based on a predicted value of the at least one coefficient of the color mapping coefficients, and wherein the predicted value of the at least one coefficient of the color mapping coefficients is a predefined fixed value;
• generate the 3D lookup table based on the number of octants for each of the color components and color values associated with the color mapping coefficients for each of the octants;
• decode residual data of video blocks of the video data;
• and
• reconstruct the video blocks of the video data based on the decoded residual data and at least one reference picture generated using the 3D lookup table.