Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Context-Based Defading of Archive Photographs | Hindawi Publishing Corporation EURASIP Journal on Image and Video Processing Volume 2009 Article ID 986183 11 pages doi 2009 986183 Research Article Context-Based Defading of Archive Photographs V. Bruni EURASIP Member 1 G. Ramponi 2 A. Restrepo 2 3 and D. Vitulano1 1Istituto per le Applicazioni del Calcolo Via dei Taurini 19 00185 Rome Italy 2DEEI Universita di Trieste Via Valerio 10 34127 Trieste Italy 3Departmento deIngenềria Electrica y Electronica Universidad de los Andes Bogota Colombia Correspondence should be addressed to V. Bruni bruni@ Received 30 January 2009 Accepted 15 September 2009 Recommended by Anna Tonazzini We present an algorithm for the enhancement of contrast in digitized archive photographic prints. It aims at producing an adaptive enhancement based on the local context of each pixel and is able to operate without direct user s intervention. A relation between the variation of contrast at different resolutions and the local Lipschitz regularity of the image is exploited. In this way each pixel is defaded according to its nature noise edge or smooth region. This strategy provides for an algorithm that drastically reduces typical annoying artifacts like halo effects and noise amplification. Copyright 2009 V. Bruni et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. Introduction Antique photographic prints are very often subject to fading. Two typical examples of faded images are shown in Figure 1. Fading can be described using a model based on silver oxidation. The intensity and speed of this process are extremely variable and depend on the technology used to get the print as well as on the way the print under consideration was processed. Indeed several factors influence the stability of a print. In the oldest salted papers fading can be traced to the .