Title :
Spatially Adaptive Wavelet-Based Method Using the Cauchy Prior for Denoising the SAR Images
Author :
Bhuiyan, M.I.H. ; Ahmad, M.O. ; Swamy, M.N.S.
Author_Institution :
Center for Signal Process. & Commun., Concordia Univ., Montreal, Que.
fDate :
4/1/2007 12:00:00 AM
Abstract :
The speckle noise complicates the human and automatic interpretation of synthetic aperture radar (SAR) images. Thus, the reduction of speckle is critical in various SAR image processing tasks. In this paper, we introduce a new spatially adaptive wavelet-based Bayesian method for despeckling the SAR images. The wavelet coefficients of the logarithmically transformed reflectance and speckle noise are modeled using the zero-location Cauchy and zero-mean Gaussian distributions, respectively. These prior distributions are then exploited to develop a Bayesian minimum mean absolute error estimator as well as a maximum a posteriori estimator. A new context-based technique with a reduced complexity is proposed for incorporating the spatial dependency of the wavelet coefficients with the Bayesian estimation processes. Experiments are carried out using typical noise-free images corrupted with simulated speckle noise as well as real SAR images, and the results show that the proposed method performs favorably in comparison to some of the existing methods in terms of the peak signal-to-noise ratio, speckle statistics and structural similarity index, and in its ability to suppress the speckle in the homogeneous regions
Keywords :
Bayes methods; Gaussian distribution; image denoising; least mean squares methods; maximum likelihood estimation; radar imaging; synthetic aperture radar; wavelet transforms; Bayesian method; Bayesian minimum mean absolute error estimator; Cauchy prior; SAR images denoising; context-based technique; despeckling; logarithmically transformed reflectance; maximum a posteriori estimator; peak signal-to-noise ratio; spatially adaptive wavelet-based method; speckle noise; structural similarity index; synthetic aperture radar; zero-location Cauchy; zero-mean Gaussian distributions; Bayesian methods; Gaussian noise; Humans; Image processing; Noise reduction; PSNR; Reflectivity; Speckle; Synthetic aperture radar; Wavelet coefficients; Cauchy distribution; spatial adaptation; speckle noise; synthetic aperture radar (SAR) image; wavelet transform;
Journal_Title :
Circuits and Systems for Video Technology, IEEE Transactions on
DOI :
10.1109/TCSVT.2006.888020