Registration of real-time X-ray image sequences for weld inspection

Real-time X-ray inspection is one of the important nondestructive testing methods used for long consecutive weld inspection. Registration of the image sequences is the foundation for spatio-temporal image processing methods in which the position relationship between image sequences is needed, such as spatio-temporal filtering, motion blur removing and defect tracking in image sequences. However, the image registration is difficult because the signal-to-noise ratio of real-time X-ray weld image is rather low and the images are quite similar along the weld direction. In this paper, the image registration processing is separated into rotation registration and translation registration. The slope angle of weld, which is calculated by weld edges, is used to implement the rotation registration. And the translation registration is implemented based on phase correlation by extracting features from difference image. The experimental results show that the proposed method is stable and precise.