Blocking artifacts reduction in block-coded images using self-similarity

Transform coding is the most popular image compression method. However, for high compression it produces noticeable blocking artifacts in the decoded image. This paper presents new algorithms for reducing blocking artifacts. The algorithms use piecewise self-similarity within different parts of the image as a priori to give reasonable modification to the block boundary pixels. The proposed postprocessing algorithm includes block classification in transform coefficient domain, and each block boundary area smoothing is performed by searching similar blocks. In experiments it outperforms an existing method and gives significant subjective and objective improvement over the decoded image.