In Fig. 4, the microscopic images of the fingerprints on a reflecting aluminum sheet are shown: (a) and (b) are bright-field images while (c) and (d) are the dark-field images. In this case, the plain fingerprint marks can hardly be seen at all in the bright-field image due to the strong reflection from the aluminum sheet [Fig. 4(b)], while the fingerprint debris can be resolved only slightly better in the dark-field image. This is due to the highly scattering nature of the rough surface of the aluminum which masks the scattering from the fingerprint debris. But it can be seen that the CTF deposition on the fingerprint debris can be clearly discerned as continuous lines in both the bright field and the dark-field images. The visibility of the fingerprint marks with the CTF deposition was comparable in the bright-field mode and the dark-field mode in this case of a highly reflecting and scattering substrate