Accelerated and Adaptive Non-local Mean Temporal Filtering for Improved HEVC Coding Efficiency

As modern video codecs exploit at their basis temporal and spatial correlations in video signal for compression, and such correlations are corrupted by noise that is present in the video signal, temporal filtering has been shown to be effective for improving coding efficiency in various encoder implementations [1], [2], [3]. In particular, the non-local mean approach in [1] has been applied in AV1, an open video coding format competing with HEVC (aka H.265), which includes built-in mechanisms that allow effective temporal filtering using non-displayable reference frames (aka ALTREF frames).