Guided Detail Filter for AVM

This paper proposes an additional filter — that aims at enhancing the fidelity of local details in reconstructed frames and consequently improving coding efficiency — to the in-loop filtering process in the AOM next generation video codec (AVM). This involves correcting each sample through a rectification (i.e., scaling and clipping) process applied to the expected coding error obtained via a multidimensional table look-up with respect to a query vector that is derived by passing the sample’s spatial neighborhood and its intensity gradients through a multichannel filter. Guiding information comprising (multichannel) linear kernels and the table of expected coding errors is chosen according to edge classification and coding settings for optimal adaptation to local sample activity and coding context. Experimental results demonstrate that our approach achieves significant improvements over AVM v7.0.1, with PSNR-Y bitrate saving of -0.57% and -0.52% for All Intra and Random Access configurations respectively.