A novel multiscale nonlinear thresholding method for ultrasonic speckle suppressing

This paper presents a novel speckle suppression method for medical B-scan u ltrasonic images. An original image is first separated into two parts with an adaptive filter. These two parts are then transformed into a multiscale wavelet domain and the wavelet coefficients are processed by a soft thresho lding method, which is a variation of Donoho's soft thresholding method. Th e processed coefficients for each part are then transformed back into the s pace domain. Finally, the denoised image is obtained as the sum of the two processed parts. A computer-simulated image and an in vitro B-scan image of a pig heart have been used to test the performance of this new method. Thi s technique effectively reduces the speckle noise, while preserving the res olvable details. It performs well in comparison to the multiscale threshold ing technique without adaptive preprocessing and two other speckle-suppress ion methods.