Image registration for defects detection of high-speed train bogies

Defects detection of high-speed train bogies by image processing has the advantages of non-contact, fast and high precision. Small defects can be identified and located quickly by comparing the current captured image with the previously saved defects-free image. Actually, the viewing angles and positions of images taken on the same location at different time are usually different. So image registration is needed before the image comparison. This paper proposes an image registration based on binocular stereo matching. The two images taken under different viewing angles or positions can be considered as a stereo image pair. The proposed method utilizes the results of image feature matching and the corresponding essential matrix to obtain the 3D coordinates of feature points. And the 3D coordinates of non-feature points can be estimated by those of adjacent feature points'. By this way, each single pixel on the current image can be re-projected into the normal image, and image registration is accomplished. Compared with the traditional methods, the result image of the proposed approach is more accurate.