Compression artifacts reduction using variational methods : Algorithms and experimental study

• Published in: 2008 IEEE International Conference on Acoustics, Speech and Signal Processing pp. 1173 - 1176
• Main Authors: Weiss, P., Blanc-Feraud, L., Andre, T., Antonini, M.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.03.2008
• Subjects: Bit rate; Compression algorithms; Convergence; Convex optimization; Image coding; Image converters; Image quality; Image restoration; Optimization methods; Transform coding; Variational methods; Wavelet transforms
• ISBN: 9781424414833; 1424414830
• ISSN: 1520-6149; 2379-190X
• DOI: 10.1109/ICASSP.2008.4517824

Many compression algorithms consist of quantizing the coefficients of an image in a linear basis. This introduces compression noise that often look like ringing. Recently some authors proposed variational methods to reduce those artifacts. They consists of minimizing a regularizing functional in the set of antecedents of the compressed image. In this paper we propose a fast algorithm to solve that problem. Our experiments lead us to the conclusion that these algorithms effectively reduce oscillations but also reduce contrasts locally. To handle that problem, we propose a fast contrast enhancement procedure. Experiments on a large dataset suggest that this procedure effectively improves the image quality at low bitrates.