Unified Loop Filter for Video Compression

This letter proposes a unified loop filter for video coding, which suppresses the quantization noise optimally and improves the objective and subjective qualities of the reconstructed picture simultaneously. The proposed filter unifies nonlinear enhancement filter and linear restoration filter within the classical optimization framework of least mean square error. To adapt to locally diverse quantization error characteristics, classification-based strategy is employed to design unified loop filters with different characteristics, which further improves the capability of picture restoration. Experimental results show that the proposed filter achieves superior objective coding gain and better visual quality improvement around edges and textures, compared with H.264/AVC high profile.