Multi-scale multi-intensity defect detection in ray image of weld bead

The radiographic test used to inspect the internal defects is an important non-destructive testing technique for welding. The weld bead radiographs of different detection scenes and different types of defects are very different, which limits the versatility of the automatic detection algorithm. This paper solves this problem by analyzing the radiographic images at different scales and intensities. Firstly, a multi-scale multi-intensity parameter space is established, and the preprocessed images corresponding to the parameters ensure that defects are not missed. Then, through the detection standard of the weld and the properties of the radiographic image, the value range of the parameters is automatically limited and the preprocessed image is optimized. Finally, algorithms for screening and merging defects in different preprocessed images are designed to reduce false detections and describe precise defect boundaries. Experimental results show that the algorithm proposed in this paper is universal, robust and accurate.