1. A method of correcting an image with perspective distortion, comprising the steps of: receiving image data including a distorted object image; setting at least a distortion parameter pertaining to the image data according to an operational instruction; calculating a plurality of coordinates of corners of the distorted object image according to the distortion parameter; determining a transformation matrix according to the calculated coordinates of the corners of the distorted object image; and transforming the distorted object image to a corrected object image according to the transformation matrix.