Edge-protection nonlinear filters for removing compression block artifacts and noise
Daben Liu, Sos С. Agaian, Joseph P. Noonan · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1997
JPEG is perhaps the most commonly used still-image standard due to its good compression rate, flexibility in choosing image quality and fast algorithm for implementation. In JPEG, the DCT is used for 8 by 8 block transforms. However the notorious block artifacts caused by the DCT are of great concern. In this article, we focus on the DCT and try different filters to smooth the annoying block boundaries which are very visible under a high compression rate. A new nonlinear filter is proposed which outperforms which are very visible under a high compression rate. A new nonlinear filter is proposed which outperforms existing techniques. The results are demonstrated for images with a comparison of mean-square-errors. For a general application, the new filter is used to cancel gaussian noise added to an image and the performance is compared with that of other commonly used filters.