1. An image alignment method comprising: a. storing a reference image and a current image in a memory, wherein the reference image is defined by a first set of local pixel blocks and the current image is defined by a second set of local pixel blocks; b. applying phase correlation to a first block in the reference image and a first block in the current image to generate a phase correlation surface between the first block of the reference image and the first block of the current image, wherein the phase correlation surface is defined by a set of correlation points each having a correlation value; c. filtering the phase correlation surface using a filter that is fit by a first quadratic surface, thereby forming a filtered phase correlation surface having a filtered set of correlation points; d. determining a sub-pel motion estimation according to a second quadratic surface and a sub-set of correlation values of the filtered set of correlation points and a largest peak correlation point, wherein the sub-set of correlation values correspond to a neighborhood of correlation points about the largest peak correlation point, thereby determining a motion vector corresponding to the first block in the current image; and e. determining a global motion between the reference image and the current image by fitting a set of motion vectors corresponding to the second set of blocks in the current image to a global motion model.