Page 121 - Automated Fingerprint Identification Systems (AFIS)

106 AUTOMATED FINGERPRINT IDENTIFICATION SYSTEMS

would be no minutiae to match against. The perpetrator has a record on file,
but there are not sufficient minutiae or image characteristics to make an iden-
tification. This can be very frustrating. To repeat, the identification technology
is severely hampered if the booking officer does not take a nail-to-nail roll cap-
turing good image characteristics.

5.2.4 INKED IMAGES VERSUS LIVESCAN IMAGES
The images captured with ink are considered by many (particularly by latent
print examiners) to be preferable to images produced by an electronic scan.
They hold that the impression produced by the ink-and-roll process by a trained
officer on certified paper stock, when the ink is uniform in distribution and the
finger is rolled from nail to nail, is the very best image possible. Inked cards
are believed to contain more definition and more information than the image
produced by a scan because of the levels of grayscale possible in the inked image
and the retention of ink on the card.
The first generation of scanned images produced by livescan machines was
captured at 500ppi, a resolution with sufficient detail to complete a tenprint
search, but not always enough for a latent print search or identification. Newer
livescan devices capture images at 1,000ppi, retaining four times as much infor-
mation as the first generation. Newer generations of livescan machines also
capture palm impressions, which may contain as much as ten times the size and
minutiae as the individual finger images.
Scanned images usually go through a quality check on the livescan machine
before the images are saved. Out-of-sequence fingers or hands, or low-quality
images, can be corrected while the subject is still being printed. Since the trans-
mission of the record to an AFIS immediately follows, the subject can be re-
rolled if the transmission is garbled. Because of the transmission of scanned
records, each image may have to be compressed prior to transmission and then
decompressed in order to display the image, which may cause the image to lose
some definition.
Which process is better process remains a topic of great debate and concern
as electronic images begin to replace paper images.

5.2.5 IMAGE CAPTURE PROCESSES

As mentioned in Chapter 4, the information contained in the paper or elec-
tronic version of the tenprint card can be divided into three sections: alpha
information, images, and minutiae. Alpha information, much of which will be
kept in the CCH file, is descriptive information about the subject, including the
name, address, reason for fingerprinting, charge, etc. This is the information