关键词: 医学超声图像, 斑点噪声, 冗余小波变换, 广义高斯分布, 贝叶斯萎缩阈值

Abstract: The inherent speckle noise in ultrasound（US） images severely degrades the image interpretation and affects the following-up image processing tasks.A speckle reduction algorithm is proposed for medical ultrasound images based on Redundant Wavelet Transform（RWT）.At first，logarithmical transform is performed to original speckled US image to transform multiplicative noise into additive ones.Secondly，redundant wavelet transform is carried out to the transformed image.Under the assumption that the statistics of wavelet coefficients is Generalized Gaussian Distribution（GGD），BayesShrink threshold is calculated for each high frequency subband，and wavelet coefficients in the subband are modified via soft-thresholding rule.Experiment results show that the presented algorithm yields better despeckling performance than traditional spatial filterings and thresholding denoising algorithms based on Discrete Wavelet Transform（DWT）.

Key words: medical ultrasound images, speckle noise, Redundant Wavelet Transform（RWT）, Generalized Gaussian Distribution（GGD）, BayesShrink thresholding