Abstract: In this paper,a new image registration algorithm is proposed to perfectly address the problem caused by rotation between images.Our algorithm is based on the observation that the geometric features at the edge of an image can provide important information for the image registration.The main novelty of the algorithm is in proposal of a fast high-precision formula being applied to calculate the tangent angles of any point at the edges,and these angles are used as robust features to estimate the approximate rotation angle between two images.By the approach,we first detect the edge of the original images for a set of feature points,calculate their tangent angle with our new formula and then use the statistical differences of the tangent angles of all feature points within two images to estimate the rotation parameters of the geometric transform.Finally,a step of coarse-to-fine image registration is performed based on the correlation criterion.Experimental results in various types of images have been provided to verify the accuracy of our automatic registration algorithm.