1. A method for uniquely identifying a subject based on an iris image of an eye of the subject, comprising: obtaining the iris image; applying at least one filter to the iris image to produce a filtered iris image, wherein said at least one filter enhances discriminative features of the iris image; applying at least one interpolation method to the filtered iris image to produce a resized iris image; applying at least one differencing process to the resized iris image to produce at least one local difference iris image; and applying at least one encoding process to said at least one local difference iris image to produce an iris code, wherein the iris code uniquely identifies the subject.