基于X射线图像的厚钢管焊缝中气孔缺陷的自动检测

由于厚钢管X射线图像强度分布不均匀，对比度低、噪声大，且气孔缺陷的大小、形状、位置、对比度各异，使得自动检测各种类型的气孔较为困难。针对传统缺陷检测算法中手工标记缺陷数据工作量大，焊缝边缘难以准确提取等问题，提出一种新的无监督学习的各种气孔缺陷检测算法。首先，采用快速独立分量分析从钢管X射线图像集合中学习一组独立基底，并用该基底的线性组合来选择性重构带气孔缺陷的测试图像；随后，测试图像与其重构图像相减获得差异图像，通过全局阈值从差异图像中将各种气孔分割出来。实验的训练集有320幅，测试集有60幅图像，所提算法检测结果的平均敏感性和准确率为90.5%和99.7%。实验结果表明，该算法无需手工标记数据或提取焊缝边缘，可准确检测各种气孔缺陷。

Automatic detection of blowholes defects in X-ray images of thick steel pipes

Due to the intensity distribution of X-ray image of thick steel pipe is not uniform, the contrast is low, the noise is big, and the size, shape, position and contrast of the blowholes defects are different, it is difficult to detect various types of blowholes automatically. Aiming at the problems that the traditional defect detection algorithm has a large workload of manually marking defect data, and the edge of the weld is difficult to accurately extract and other issues, a new unsupervised learning algorithm was proposed for the detection of various blowholes defects. Firstly, fast Independent Component Analysis (ICA) was used to learn a set of independent base vectors from the steel pipe X-ray image set, and a linear combination of the base vectors was used to selectively reconstruct the test image with blowholes defect. Then, the test image was subtracted from its reconstructed image to obtain the difference image, and the various blowholes were separated from the difference image by global threshold. There were 320 images in the training set and 60 images in the test set. The average sensitivity and accuracy of the proposed algorithm were 90.5% and 99.7%. The experimental results show that the algorithm can accurately detect all kinds of blowholes defects without manual marking the data or extracting the edge of the weld.