A fast algorithm for image registration without predetermining correspondences.

A novel approach for efficient image registration is proposed. The proposed method applies wavelet transforms to extract a number of feature points as the basis for registration. From the selected feature points, a subset of possible matching pairs is selected to obtain the desired registration parameters. This subset is chosen by using the orientation difference between two target images as a criterion to eliminate spurious matching pairs. In order to predetermine the orientation difference between two target images, a so-called histogram is calculated. From the angle histogram, the orientation difference can be decided. Once the orientation difference is obtained, the desired subset can be easily determined. By randomly selecting two matching pairs from this subset, a set of registration parameters can be obtained. By checking how many matching pairs are compatible with the selected parameters, the best estimation can be determined. Compared with conventional algorithms, the proposed scheme is a great improvement in terms of efficiency as well as reliability for the image registration problem.