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Before latent fingerprints are
scanned into an NEC AFIS computer, they must be photographically enlarged,
traced, and the tracing then later photographically reduced to the
one-to-one size of the latent fingerprint. This is done because latent
prints are usually dark gray or black on a light gray or dirty surface.
There can be water spots, greasy marks, or bits of sand, dirt or debris to
interfere with the scanner. The computer has difficulty scanning this small,
yet finely-detailed image unless it is high-contrast and has little or no
background "noise." The easiest way to achieve this high-contrast,
finely-detailed image is to trace the latent fingerprint, drawing in only
the ridge details and leaving out the smudges, dirt and broken ridges.
The NEC computer experts have
determined that only a certain brand of tracing paper is acceptable. This is
the "official", pal .002 Clear Matte Polyester Tracing Film (Somar-Palna
B-200) required by the NEC system. Each box contains 100 sheets (8 1/4" x 11
3/4"). |
