A Spatially Adaptive Gradient-Projection Algorithm to Remove Coding Artifacts of H.264

Kwon-Yul CHOI  Min-Cheol HONG  

IEICE TRANSACTIONS on Information and Systems   Vol.E94-D   No.5   pp.1073-1081
Publication Date: 2011/05/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E94.D.1073
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Image Processing and Video Processing
H.264,  coding artifacts,  weighted constrained least squares,  human visual system,  projection onto convex sets,  

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In this paper, we propose a spatially adaptive gradient-projection algorithm for the H.264 video coding standard to remove coding artifacts using local statistics. A hybrid method combining a new weighted constrained least squares (WCLS) approach and the projection onto convex sets (POCS) approach is introduced, where weighting components are determined on the basis of the human visual system (HVS) and projection set is defined by the difference between adjacent pixels and the quantization index (QI). A new visual function is defined to determine the weighting matrices controlling the degree of global smoothness, and a projection set is used to obtain a solution satisfying local smoothing constraints, so that the coding artifacts such as blocking and ringing artifacts can be simultaneously removed. The experimental results show the capability and efficiency of the proposed algorithm.