1. A method for correcting skew images comprising the steps of: (a) detecting a plurality of edge areas on an image, each of the edge areas having an edge; (b) calculating a plurality of gradient angles of the edge areas to sum up weightings of the gradient angles; and (c) rotating the image according to the gradient angle with the highest weighting; wherein the edge represents that the maximum display difference in each of the edge areas is larger than a threshold.