A method of decoding video data, the method comprising: determining a number of octants for each of three color components of a three-dimensional lookup table for color gamut scalability; for each of the octants for each of the color components, decoding 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 decoding the color mapping coefficients comprises, for a first one of the octants for each of the color components, decoding 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, wherein the at least one coefficient of the color mapping coefficients comprises a key coefficient that defines a weighting factor for the linear color mapping function between a same color component of the lower layer of the video data and the higher layer of the video data, and wherein, for the first one of the octants for each of the color components, decoding the key coefficient based on a predicted value equal to a predefined non-zero value, and decoding remaining coefficients of the color mapping coefficients based on a predicted value equal to zero; 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; decoding residual data of video blocks of the video data; and 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. determining a number of octants for each of three color components of a three-dimensional lookup table for color gamut scalability; for each of the octants for each of the color components, decoding 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 decoding the color mapping coefficients comprises, for a first one of the octants for each of the color components, decoding 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, wherein the at least one coefficient of the color mapping coefficients comprises a key coefficient that defines a weighting factor for the linear color mapping function between a same color component of the lower layer of the video data and the higher layer of the video data, and wherein, for the first one of the octants for each of the color components, decoding the key coefficient based on a predicted value equal to a predefined non-zero value, and decoding remaining coefficients of the color mapping coefficients based on a predicted value equal to zero; 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; decoding residual data of video blocks of the video data; and 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.