Title :
Reducing artifacts in BDCT-coded images by adaptive pixel-adjustment
Author_Institution :
Sch. of Eng. & Ind. Design, Univ. of Western Sydney, NSW, Australia
Abstract :
Generating artifacts is a major problem with compressed images coded by the block discrete cosine transform (BDCT). An iterative deblocking method based on projection onto convex sets (POCS) is presented in this paper. The method considers pixel-wise local adaptability. The adjustment of a pixel is determined by local properties of the pixel. A coded image is iteratively projected onto two locally adaptive smoothness constraint sets, a locally adaptive quantization constraint set and an intensity constraint set to obtain an improved image where artifacts are reduced. The proposed method is tested on JPEG encoded images with excellent results.
Keywords :
discrete cosine transforms; image coding; iterative methods; quantisation (signal); set theory; smoothing methods; JPEG encoded images; adaptive pixel adjustment; adaptive quantization constraint set; adaptive smoothness constraint set; artifact reduction; block discrete cosine transform; compressed coded images; intensity constraint set; iterative deblocking method; projection onto convex sets; Adaptive control; Australia; DC generators; Design engineering; Discrete cosine transforms; Image coding; Image reconstruction; Pixel; Programmable control; Quantization;
Conference_Titel :
Pattern Recognition, 2004. ICPR 2004. Proceedings of the 17th International Conference on
Print_ISBN :
0-7695-2128-2
DOI :
10.1109/ICPR.2004.1334179
