Compression artifact reduction for low bit-rate images based on non-local similarity and across-resolution coherence

This paper proposes a method to estimate coefficients for blocking artifact reduction at low bit rate. Across-resolution coherence that low and high resolution image are similar is introduced to preserve signal continuity. Non-local similarity is used to provide samples for estimation by searching similar blocks of reference block. We have two sources of estimation. One source is exploiting non-local similarity to estimate coefficients of low resolution of decoded image, and interpolating the low resolution image to high resolution. We obtain the coefficients estimation for high resolution image based on the coherence across different resolutions. The other source of estimation is the quantization coefficients. These estimations are fused by their reliability respectively. Experimental results demonstrate that the proposed algorithm outperforms some recently presented methods in terms of both objective and subjective qualities of the reconstruction images.