Adaptive loop filter with directional features and similarity mapping for video coding

PoLin Lai; Felix C. A. Fernandes

doi:10.1117/12.909750

15 February 2012 Adaptive loop filter with directional features and similarity mapping for video coding

PoLin Lai, Felix C. A. Fernandes

Proceedings Volume 8305, Visual Information Processing and Communication III; 830506 (2012) https://doi.org/10.1117/12.909750
Event: IS&T/SPIE Electronic Imaging, 2012, Burlingame, California, United States

Abstract

To improve both coding efficiency and visual quality of video coding, in this paper, we present an adaptive loop filtering design which exploits local directional characteristics exhibit in the video content. The design combines linear spatial filtering and directional filtering with a similarity mapping function. We compute and compare multiple simple directional features to classify blocks in a video frame into classes with different dominant orientations. Each class of blocks adapt to a directional filter, with symmetric constraints imposed on the filter coefficients according to the dominant orientation determined by the classification. To emphasis pixel similarity for explicit adaptation to edges, we use a simple hard-threshold mapping function to avoid artifacts arising from across-edge filtering. Our design uses only 4 filers per frame with fixed 7×7 diamond-shaped filter support, while achieving better coding efficiency and improved visual quality especially along edges, as compared to other approaches using up to 16 filters with up to 7 vertical × 9 horizontal diamond-shaped filter support.

Citation Download Citation

PoLin Lai and Felix C. A. Fernandes "Adaptive loop filter with directional features and similarity mapping for video coding", Proc. SPIE 8305, Visual Information Processing and Communication III, 830506 (15 February 2012); https://doi.org/10.1117/12.909750

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