瑞利微调双边滤波超声图像降噪去斑算法

Noise and speckle reduction of ultrasonic images using an improved Rayleigh-trimmed bilateral filtering algorithm

为有效抑制超声图像的噪声和斑点,提出了一种新的瑞利微调双边滤波器(Rayleigh-trimmed bilateral filter,RBF)。方法采用先噪声检测再针对性滤波的两步骤方案,并充分利用了噪声及斑点的分布统计特性。根据排序象限中值向量(SQMV)准则计算出滤波窗口的相关中值,通过比较该值和目标像素值,可将目标像素分为噪声、斑点和边缘像素;用双边滤波器和瑞利微调滤波器分别滤除噪声和斑点而保持边缘像素不变。用合成和真实超声图像的视觉效果和客观指标评估提出方法的性能,实验结果表明,该算法能有效地滤除超声图像的斑点和噪声并且较好地保留图像的边缘细节特征。

To suppress noise and speckle in ultrasound images efficiently, a new Rayleigh-trimmed bilateral filter （RBF） is pro posed. The proposed method makes use of the statistical characteristics of noise and speckle, and then the two-step algorithm which contains a texture and noise detector is adopted to reduce noise and speckle while keeping the noise-free pixel unchanged. Firstly, the target pixel is classified as noise, speckle or noise-free based on the sorted quadrant median vector （SQMV） scheme by calculating a reference median in the filtering window and comparing it with the target pixel. Subsequently, bilateral filter and Rayleigh-trimmed filter are switched to filter noise and speckle, respectively. Visual and numerical indices on synthetic and real ultrasound images are used to evaluate the performance of the proposed method, experiment results indicate that the algorithm is effective to reduce speckle and noise in ultrasonic images while reservin~ edge details