Page 274 - Automated Fingerprint Identification Systems (AFIS)

APPENDIX A: GLOSSAR Y 259

LT/LT SEARCH—A search of a latent print against other latent prints, which
are usually stored in the unsolved latent (UL) file. Has potential to link
crimes committed by the same person, even though that person is as yet
unidentified. Also referred to as a LT/UL search.
LT/TPid SEARCH—A search of a latent print against the tenprint identifica-
tion database.
LT/TPlc SEARCH—A search of a latent print against the tenprint latent cog-
nizant (ten finger) database.
LT/UL SEARCH—See LT/LT search.
MASTER NAME INDEX—A subject identification index maintained by crimi-
nal history record repositories that includes the name and other identifiers
for each person with a record on the database.
MATCH—Condition of retrieving a file subject that, because of matcher
score, falls within selection criteria for the probability of a mate to a search
suspect.
MATCHER—An AFIS component that compares the minutiae database fea-
tures of a search print with file prints and selects the file print that comes
closes to matching the search print.
MATCHER ACCURACY—A measure of the matcher subsystem’s ability to place
the correct mates as the selected candidate as a result of the matcher process.
Also a measure of the matcher subsystem’s ability to select no candidate if
the mate is not in the database.
MATCHER QUALITY INDEX (MQI)—Value representing the sum of the
“equivalent number of minutiae” for fingers 2 and 7 (generally the search
fingers). The index is a complex metric that weights the actual minutia count
using local image quality and the number of neighbors in computation. On
the average fingerprint, AFIS/FBI produces about 88 minutiae, and the
average value for the equivalent number of minutia is about 56. Images with
higher values for MQI are more likely to be successfully matched by IAFIS.
MATCHER RELIABILITY—Probability that the mate fingerprint will be
selected as the primary candidate by the matcher if the mate is in the file
being searched or that no candidate will be selected if the mate is not in the
file being searched. Also the probability that the matcher will function as
intended for a specified interval under specific conditions.
MATCHING SCORE—The numerical result of comparing the minutiae data of
two fingerprint digital representations.
MATE—A fingerprint that matches another impression from the same finger.
MINUTIAE—Friction ridge characteristics, which are used to individualize that
print. Minutiae occur at points where a single friction ridge deviates from an
uninterrupted flow. Deviation may take the form of ending, dividing into two
or more ridges, or immediate origination and termination.