A biometric authentication system, including a database of digital images of biometrics of known people, a camera for capturing a digital image of a biometric of an unknown person, a two-dimensional gradient filter coupled with said database and said camera for deriving a spatial gradient of a digital image, and a match processor coupled with the two-dimensional gradient filter for processing two spatial gradients and determining the extent to which the unknown biometric corresponds with a known biometric. A method and a computer-readable storage medium are also described and claimed.