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 A New Denoising System for SONAR Images | Hindawi Publishing Corporation EURASIP Journal on Image and Video Processing Volume 2009 Article ID 173841 14 pages doi 2009 173841 Research Article A New Denoising System for SONAR Images Alexandru Isar 1 Sorin Moga 2 and Dorina Isar1 1 Electronics and Telecommunications Faculty Politehnica University y Parvan Boulevard 300223 Timisoara Romania 2Institut TELECOM TELECOM Bretagne Lab STICC CNRS UMR 3192 Brest France Correspondence should be addressed to Alexandru Isar Received 1 November 2008 Revised 21 May 2009 Accepted 21 July 2009 Recommended by Sven Loncaric The SONAR images are perturbed by speckle noise. The use of speckle reduction filters is necessary to optimize the image exploitation procedures. This paper presents a new denoising method in the wavelet domain which tends to reduce the speckle preserving the structural features and textural information of the scene. Shift-invariance associated with good directional selectivity is important for the use of a wavelet transform WT in many fields of image processing. Generally complex wavelet transforms for example the Double Tree Complex Wavelet Transform DT-CWT have these useful properties. In this paper we propose the use of the DT-CWT in association with Maximum A Posteriori MAP filters. Such systems carry out different quality denoising in regions with different homogeneity degree. We propose a solution for the reduction of this unwanted effect based on diversity enhancement. The corresponding denoising algorithm is simple and fast. Some simulation results prove the performance obtained. Copyright 2009 Alexandru Isar 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 The SONAR images represent a particular case of Synthetic Aperture Radar SAR images. The SAR images are perturbed by speckle. It
