We present a Wiener filter that is especially suitable for speckle and noise reduction in multilook synthetic aperture radar (SAR) imagery. The proposed filter is nonparametric, not being based on parametrized analytical models of signal statistics. Instead, the Wiener–Hopf equation is expressed entirely in terms of observed signal statistics, with no reference to the possibly unobservable pure signal and noise. This Wiener filter is simple in concept and implementation, exactly minimum mean-square error, and directly applicable to signal-dependent and multiplicative noise. We demonstrate the filtering of a genuine two-look SAR image and show how a nonnegatively constrained version of the filter substantially reduces ringing.
© 2000 Optical Society of America
(100.2000) Image processing : Digital image processing
(100.2980) Image processing : Image enhancement
(100.3020) Image processing : Image reconstruction-restoration
(280.6730) Remote sensing and sensors : Synthetic aperture radar
Robert S. Caprari, Alvin S. Goh, and Emily K. Moffatt, "Noise and speckle reduction in synthetic aperture radar imagery by nonparametric Wiener filtering," Appl. Opt. 39, 6633-6640 (2000)