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Speckle filtering in SAR images by contrast modification, comparison with a large class of filters

Filtrage du speckle dans les images ros par modification de contraste, comparaison avec une grande classe de filtres

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Abstract

Speckle appearing in synthetic aperture radar (sar) images is generated by coherent processing of radar signals. Basically the speckle has the nature of multiplicative noise. Recently, several methods have been proposed to remove speckle in sar images, among them, Lee’s methods, Frost’s method and Zamperoni’s method. In this paper, we propose an effective method for smoothing speckle-corrupted images. Digital processing is introduced, based on a contrast modification in a multi-resolution pyramid image representation. The contrast modification is realized by a median filter or an adaptive order filter giving a reconstructed image. For assessing this new method, we realized a comparative study with several noise-smoothing algorithms.

Résumé

Le phénomène du speckle est caractéristique des images laser, des images radiographiques et des images radar à ouverture synthétique (ros). Dans ces images le speckle se présente comme une granularité ayant les caractéristiques d’un bruit aléatoire multiplicatif. Plusieurs méthodes ont été proposées récemment pour la réduction du speckle dans les images ros, les principales étant celles de Lee, de Frost, de Zamperoni. Dans cet article, une nouvelle méthode de réduction du speckle est proposée. Celle-ci est basée sur la modification du contraste de l’image à partir d’une représentation multi-résolution pyramidale. La modification du contraste à chaque étage de la pyramide est réalisée à l’aide d’un filtre médian ou d’un filtre d’ordre adaptatif. L’image est reconstruite à partir du contraste modifié et engendre ainsi l’image filtrée. Pour évaluer les performances de cette nouvelle méthode, une étude comparative avec les principales méthodes existantes a été réalisée.

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Authors and Affiliations

  1. sei (Systèmes Electroniques et Informatiques), ireste, La Chantrerie, CP 3003, F-44087, Nantes Cedex 03, France

    Ali Saad, Safwan EL Assad & Dominique Barba

Authors
  1. Ali Saad
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  2. Safwan EL Assad
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  3. Dominique Barba
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Saad, A., Assad, S.E. & Barba, D. Speckle filtering in SAR images by contrast modification, comparison with a large class of filters. Ann. Télécommun. 51, 233–244 (1996). https://doi.org/10.1007/BF02999803

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  • DOI: https://doi.org/10.1007/BF02999803

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