超声全聚焦成像中等声程线伪影剔除方法

针对超声全聚焦成像算法中等声程线扩散产生的原理性伪影问题，提出了一种基于超声回波声场有效等声程线和图像强度分布特征相结合的伪影剔除方法。首先分析了全聚焦成像算法中等声程线产生伪影的机理，根据数据均方根误差自适应辨识有效等声程线；通过Canny算子获取全聚焦图像待处理候选区域，再根据候选区域中有效等声程线相交次数和图像强度的分布特征辨识缺陷图像和伪影，利用图像中强度最低像素值扩展填充剔除伪影后的区域，进而达到剔除伪影的目的。通过在不同直径通孔类和槽类标准缺陷试块上声场模拟实验，结果表明伪影剔除效果显著。同时，该方法对噪声也有一定的抑制能力，在不加滤波的条件下信号信噪比高于15 dB时就可获得较好的去伪影效果。

The method of eliminating isoacoustic contour artifacts in ultrasonic total focus method

Aiming at the problem of artifacts caused by the diffusion of Isoacoustic contour of ultrasonic total focus method, an artifact elimination method based on the combination of Isoacoustic contour of the ultrasonic echo field and the characteristic of image intensity distribution is proposed. Firstly, it analyzes the mechanism of the artefacts caused by the diffusion of Isoacoustic contour of ultrasonic total focus method, and adaptively identifies the effective Isoacoustic contour according to the root mean square error of the data; obtains the candidate area of the ultrasonic total focus method images by the Canny operator which to be processed, and then identify defects and artifacts according to the times of effective Isoacoustic contours intersections and the characteristic of image intensity distribution in the candidate area, and use the lowest intensity pixel value in the image to expand and fill the area which are eliminated artifacts, thereby achieving the purpose of removing artifacts. Through ultrasonic field simulation experiments on different diameters holes and grooves standard defect test blocks, the results show that the artifact eliminated effect is significant. At the same time, this method has a certain ability to suppress noise. When the signal-to-noise ratio is higher than 15dB under the condition of no filtering, the better artifact eliminated effect can be obtained.