基于树状小波的超声医学图像阈值函数降噪

The De-noising of the Ultrasound Medical Image with Threshold Functions Based on Tree-structure Wavelet Analysis

针对超声医学图像中存在特有的斑点噪声,利用树状小波分解比传统小波分解精度高的特点,将超声医学图像进行树状小波分解,然后分别采用硬阈值、软阈值和半软阈值函数三种方法进行降噪处理。结果表明半软阈值函数方法是较优阈值函数方法,可以有效地降低原图像的斑点噪声并保留图像细节。

There were inherent speckle noises in the ultrasound medical image. Th e tree-structure wavelet had higher resolution than the conventional wavelet. Th erefore, the ultrasound medical image was discomposed to the tree-structure wave let domain. Then its coefficients were shrunk with the three methods of hard thr eshold, soft threshold, and semi-soft threshold function differently for the ima ge de-noising. The result indicated that the semi-soft threshold was the effecti ve function method. The speckle noise in the original image was removed efficien tly and at the same time the image details were reserved.