Speckle reduction and enhancement of SAR images in the wavelet domain

Three methods are investigated for speckle reduction and enhancement of synthetic aperture radar (SAR) images in the orthogonal wavelet domain. The first method is a nonlinear method based on soft thresholding the wavelet coefficients for logarithmically transformed SAR image data (Guo et al. 1994). The second method uses an enhanced adaptive Lee filter (Lopes et al., 1990) of the wavelet coefficients of SAR images. Finally, the third method introduces nonlinear speckle reduction based on adaptive sigmoid thresholding of the wavelet coefficients for logarithmically transformed SAR images. The wavelet methods show great promise for speckle removal and hence provide better detection performance for SAR based recognition.