辐射图像脉冲去噪方法

An Impulse Noise Removing Method in Radiography

为去除辐射图像中的脉冲噪音,建立了一种先进行脉冲噪音检测再进行噪音数据修复的联合去噪音方法.首先采用测地膨胀方法从减灰度图像出发对原图像进行形态学灰度重构,再采用灰度阈值法从原图像与重构图像的差值图像中分割检测出脉冲噪音,然后采用改进非本地均值方法对噪音数据进行修复.改进非本地均值方法对相似像素的选择范围进行了限制,从原理上避免了传统非本地均值方法用于去除辐射图像脉冲噪音时易发生的以错纠错问题,本文对其进行了数学表述.实验证明,该方法对不同类型辐射图像的脉冲噪音均具有较好滤除效果,表现出良好的噪音数据修复和图像细节保护能力.

By analyzing of the causes and features of impulse noises in radiography,a joint denoising method based on impulse noise segmentation and data repair is presented.The radiograph is reconstructed from its gray-reduced image by geodesic dilation method,and impulse noises are segmented from the differential image between the reconstructed image and the radiograph by the global thresholding technique.The impulse noises in the radiograph are removed by an improved NL-means filter method.To avoid an intrinsic problem that fixes noise by noise in the classical NL-means method,the improved NL-means method limits the searching area of the similar pixels.An equation is used to describe the improved NL-means filter.The experimental results show that impulse noises in different radiographs can be removed effectively by the joint method,and the trivial information of the radiographs remains with high fidelity.