JVET-AG0172 EE2-related: Chroma LIC derivation with template costs [T. M. Bae, S. Deshpande (Sharp)]

This input document proposes deriving and utilizing chroma LIC flags. The derived chroma LIC flags are used to control LIC processing of chroma components separately. The derivation process of chroma LIC flags avoids the signalling of these chroma flags. When the LIC flag of the CU is enabled, chroma LIC flags are derived by utilizing the template costs that are used to derive the LIC flag of merge candidates in ECM. On top of ECM-11.0, the performance of the proposed method is reported as follows:

LB: {-0.07%, 0.26%, 0.11% }

No RA results were provided in the contribution.

In ECM-11, one LIC flag is sent to control whether LIC is enabled for all three colour components. This proposal suggests to use the signaled flag to control LIC for luma component only, and use template cost to determine whether LIC should be enabled for the two chroma components.

It was asked why RA results couldn’t be made available, the proponent said that different thresholds to determine whether to enable LIC for chroma or not based on the proposed method are needed for RA config, however optimal values for those thresholds have not been found yet.

Overall, the current gain in LB is small (small luma gain and some chroma loss), and performance in RA is not available.

Further study of this was requested.