1. An image processing method for image alignment, comprising: sequentially receiving a plurality of images; generating at least one threshold corresponding to each image according to a plurality of intensities of each image of the plurality of images; converting each image according to the thresholds of each image, for generating a plurality of binary images; acquiring a plurality of characteristic pixels of each binary image according to the plurality of binary images; and aligning the plurality of images according to the plurality of characteristic pixels of each binary image.