1. An image registration method of processing a distorted image Y into a registered image Y* which is aligned with a reference image X, the method comprising: (a) determining a scale factor “a” between the reference image X and the distorted image Y; (b) resizing the reference image X with an inverse of the scale factor “a”, thereby generating a resized reference image X 2 ; (c) determining a rotation angle “θ 0 ” between the resized reference image X 2 and the distorted image Y; (d) rotating the distorted image Y by the rotation angle “−θ 0 ” to generate a rotated distorted image Y 3 ; and (e) resizing the rotated distorted image Y 3 with the scale factor “a”, thereby obtaining the registered image Y*.