CCALF COEFFICIENT DERIVATION USING COMBINED NEIGHBORS

Loop filtering is widely used in recent video coding standards to reduce coding artifacts introduced by prediction and residual coding process. Versatile Video Coding (VVC) standard employs Cross Component Adaptive Loop Filter (CCALF) to improve chroma fidelity. This paper describes CCALF coefficient derivation that uses combined luma neighboring pixels. With the proposed combination, more correlated pixels provide less contribution to CCALF process resulting in improving performance. Simulation results show the proposed method has combined BD-rate gains of -1.51%, -2.01%, -2.40% for all intra (AI), random access (RA), and low delay (LB) conditions, respectively, compared to VTM-7.0 reference software.