Robust 3D LUT estimation method for SHVC color gamut scalability

Color gamut scalability (CGS) in scalable extensions of High Efficiency Video Coding (SHVC) supports scalable coding with multiple layers in different color spaces. Base layer conveying HDTV video in BT.709 color space and enhancement layer conveying UHDTV video in BT.2020 color space is identified as a practical use case for CGS. Efficient CGS coding can be achieved using a 3D Look-up Table (LUT) based color conversion process. This paper proposes a robust 3D LUT parameter estimation method that estimates the 3D LUT parameters globally using the Least Square method. Problems of matrix sparsity and uneven sample distribution are carefully handled to improve the stability and accuracy of the estimation process. Simulation results confirm that the proposed 3D LUT estimation method can significantly improve coding performance compared with other gamut conversion methods.