Suppression of speckle in SAR images using wavelet-based HMM

In order to suppress the speckle appearing in synthesis aperture radar (SAR) images, a novel speckle reduction method based on wavelet domain hidden Markov tree (HMT) was proposed. First, logarithmic transform for the image was performed to change the statistical property of the speckles. Then an HMT was constructed in the correspondent wavelet domain. Based on this model, the image signal was restored by maximum likelihood estimation and the speckle noise was suppressed. It is shown from the illustrative example for SAR image that the performance of the method is satisfactory for both speckle smoothing and edges presentation, and for generating visually natural images as well.