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Refined adaptive speckle filtering for SAR images / Y. Smara (31/05/1999)

Public contenu dans Remote sensing in the 21st century : economic and environmental applications / José Luis Casanova (2000) Titre : Refined adaptive speckle filtering for SAR images Type de document : Article/Communication Auteurs : Y. Smara, Auteur Editeur : Lisse et Amsterdam : Balkema (August Aimé) Année de publication : 31/05/1999 Conférence : EARSeL 1999, 19th symposium, Remote sensing in the 21st century : economic and environmental applications 31/05/1999 02/06/1999 Valladolid Espagne Importance : pp 549 - 555 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] filtre de déchatoiement [Termes IGN] image radar [Termes IGN] Laghouat (Algérie) [Termes IGN] radar à antenne synthétique Résumé : (Auteur) The presence of speckle in SAR images reduces the ability to perceive fine details and rules out a visual perception of systematic structures that would make it possible to describe a specific feature of the earth's surface and makes the radiometric and textural aspects less efficient for class discrimination. Many adaptive filters have been developed for speckle reduction and they are based on a test related to the local coefficient of variation of the observed image, which describes the heterogeneity of the scene. In this paper, the well-known non linear adaptive filters such as Frost, Wu, and Nezry filters are presented, and considering the limitations of the analysed filters and the good results achieved using the ratio edge extraction, a modified adaptive speckle filter has been implemented based on both geometrical and statistical properties (coefficient of variation) of the local area. The procedure has depended on several parameters such as window size, the width of the linear features, the thresholds, the values of Cu (coefficient of variation of multiplicative noise) and Cmax(the maximum value of the distribution of Cu). The successful use of the ratio edge and line detectors has been employed in adaptive speckle filter, in order to apply the enhanced frost version in every window or subwindow selected. As was expected, the new filter performs better, i.e., we can achieve very good smoothing in the homogeneous areas preserving, at the same time, structural and textural information, edges, linear features. The filters are tested on a ERS-1 SAR image corresponding to an area of southern Algeria called Laghouat. The good results obtained and the improvements with respect to the classic algorithms are presented and discussed. Numéro de notice : C1999-074 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Communication Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65818