Reducing artifacts in JPEG decompression by segmentation and smoothing

The major artifacts of the JPEG compressed images are blocking and ringing, which are mainly due to the coarse quantization of low frequency and high frequency DCT components, respectively. At a very low bit rate, these artifacts might be rather disturbing to human eyes. While research for reduction of blocking effects has been relatively extensively conducted, little has been done for improving ringing. The latter is particularly dominant in document images, where sharp edges present commonly in text and graphics are more likely to be encountered. In this paper we propose an algorithm, which was designed mainly for ringing effects removal. The same principle can be also applied to reduce blocking effects