Page 96 - Automated Fingerprint Identification Systems (AFIS)

AFIS SUMMAR Y—HOW THE SYSTEM WORKS 81

Figure 4.5
Local CSS Patrol
Latent Print Processing
Overview
Of
Value

Search Search
IAFIS AFIS Latent Cog
Records

Save to
Relaunch
Verification UL File

is digitized. The examiner can check for image quality and if not satisfied,
re-digitize the image. Next, the examiner, with the help of the coder, identifies
and marks each minutia on the image of the fingerprint displayed on the input
workstation, selects orientation, and repeats the process with each additional
latent print.
The function of the coder is to identify or code the minutiae in the finger
image. The ridge endings, bifurcations, and direction provide unique identifi-
cation points. Intervening ridges between minutiae may also provide unique
information. The minutiae points are identified by the coder and displayed on
the screen. The examiner may choose to add additional minutiae points not
found by the coder, or remove points considered marginal.
After all latents have been entered, the latent examiner checks the work and
launches the case. The latent fingerprint is searched by the matchers against a
latent cognizant database containing hundreds of thousands or even millions
of images. Candidates for a match are made available at a verification worksta-
tion at the originating central or remote site and are retrieved for verification.
Print images of the candidates are displayed side by side with the image of the
latent print. Various functions assist in the verification process, including locked
cursor movement and marking verification points. The latent and candidate
images may also be sent to a high-quality image printer for an off-screen com-
parison. As part of their business practice, many agencies require that the iden-
tification of a latent print be confirmed by a second latent print examiner. The
practices may also require that the identification be made from a comparison
of the latent image against the printed fingerprint card.
It must be stressed that AFIS is only a tool used by the latent examiner. It is
the latent examiner who determines if the latent image is of value, who selects
the search criteria, and who examines the lists of candidates produced by the