Scheme of retaining image edge features in JPEG image compression technology
Chunsheng Wang, Jie Li, Anlong Jiao · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1998
The features of image edges are very important in its applications such as in medicine and remoting images. JPEG image compression standard has now gained wide applications, which take advantage of the features of human visual system. It quantizes the low frequency DCT coefficients with fine level and quantizes the high frequency DCT coefficients with coarse level. But JPEG does not specifically process the image edges, which partly hiding in high frequency DCT coefficients. On analyzing the spectrum of image edge features, this paper got the energy distribution of DCT coefficients of a image subblock with a single straight edge through theoretical deduction and illustration by numerical examples. And we designed a quantization table (Q table) in JPEG. Experiments show that the Q table does not influence the image subblock with no single straight edge and can retain the image edge of image subblock with a single edge effectively.