SPECKLE SUPPRESSION USING RECURSIVE WAVELET TRANSFORMS

An effective algorithm for digital image noise smoothing using wavelet transform techniques is presented in this paper. This algorithm is mo re powerful when compared to other existing filtering algorithms in te rms of speckle suppression for synthetic aperture radar images where t he presence of speckle makes the ratio of standard deviation to mean ( STM) very high. Examples show that the original STM of about 0.30 (equ ivalent to three-look images) can be reduced to 0.05-0.03 (equivalent to more than 100-look images), with a possible small sacrifice of losi ng some details and narrow edges. The quantitative analysis is carried out and compared with the results of some existing filtering algorith ms including median, K nearest neighbour averaging, Lee's multiplicati ve and Crimmins' geometric filters, showing that imagery filtered by t he wavelet transform is the smoothest.