Decoder-side chroma intra prediction mode gradient-based derivation

Abstract

A VVC-standard encoder and a VVC-standard decoder are provided, implementing a decoder-side chroma intra prediction mode gradient-based derivation method, which improves coding efficiency of chroma intra prediction, thereby saving on signaling cost. A VVC-standard decoder configures one or more processors of a computing system to derive one of multiple possible chroma intra prediction modes by computing gradients of adjacent luma samples and chroma samples of a current chroma block. With minimal increase in signaling cost, the VVC-standard coding and decoding processes are enhanced to base intra prediction modes for chroma blocks on collocated luma block-adjacent reconstructed luma samples adjacent reconstructed chroma samples, enabling prior computational work done on coding and decoding adjacent blocks to be referenced. In this fashion, coding gains can be achieved in matching texture characteristics of the current chroma block based on a texture gradient including adjacent blocks.