An optical fingerprinting method extracts high quality latent fingerprints
from a surface without any invasive chemical or physical contact with the
examined object, and requires no cooperation of the subject. Rather than
employing extraneous material, the optical properties of the latent
fingerprint are used to generate one or more images with sufficient
contrast to distinguish the latent fingerprint or some other deformation
in the surface. The system includes a light source oriented to apply
light at an angle of incidence to the surface at the position to be
examined for the latent fingerprint or deformation, a camera oriented to
receive light specularly and diffusely reflected from the surface and/or
by the fingerprint or deformation on the surface, and a processor that
performs the computation for digital contrast enhancement and/or
reprojection of the recovered fingerprint image to a frontal view if
necessary. The technique uses optical polarization properties to enhance
the images by placing a linearly polarized filter(s) in front of the
observing camera. At least two pictures of the same scene with the same
lighting and view angle arrangement are taken whereby each of the
pictures differ only in that the orientations of the polarization filter
are different. At least two light polarization parameters for each pixel
are computed from the two or more images taken with different polarizer
orientations. An image with each pixel value representing the value of
one of the polarization parameters or a function of the polarization
parameters is generated and displayed, with some digital contrast
enhancement and/or reprojection applied. The hidden latent fingerprint
pattern is revealed in at least one such image with the interfering
background pattern significantly suppressed.