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  • Research Article
  • Open Access

M-Estimators of Roughness and Scale for -Modelled SAR Imagery

  • 1Email author,
  • 1 and
  • 2
EURASIP Journal on Advances in Signal Processing20022002:297349

  • Received: 31 July 2001
  • Published:


The GA0 distribution is assumed as the universal model for multilook amplitude SAR imagery data under the multiplicative model. This distribution has two unknown parameters related to the roughness and the scale of the signal, that can be used in image analysis and processing. It can be seen that maximum likelihood and moment estimators for its parameters can be influenced by small percentages of "outliers"; hence, it is of outmost importance to find robust estimators for these parameters. One of the best-known classes of robust techniques is that of M-estimators, which are an extension of the maximum likelihood estimation method. In this work we derive the M-estimators for the parameters of the distribution, and compare them with maximum likelihood estimators with a Monte-Carlo experience. It is checked that this robust technique is superior to the classical approach under the presence of corner reflectors, a common source of contamination in SAR images. Numerical issues are addressed, and a practical example is provided.


  • inference
  • likelihood
  • M-estimators
  • Monte-Carlo method
  • multiplicative model
  • speckle
  • synthetic aperture radar
  • robustness

Authors’ Affiliations

Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, 5000, Argentina
Centro de Informática, Universidade Federal de Pernambuco, CP 7851, Recife, PE, 50732-970, Brazil


© Bustos et al. 2002