Safescan TA-900 series Manual - page 50
50
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Each time a user’s fingerprint is scanned, the safescan TA-900 series searches its database for a matching
fingerprint. if the safescan TA-900 series finds the user’s fingerprint, then his/her “attendance” is recorded in the
safescan TA-900 series “audit log” and will be noted in subsequent reports.
13.2 Getting Good Fingerprint Images
The quality of fingerprint images is relative to the number of minutiae points captured by the safescan TA-900 series
sensor. Fingerprint images not possessing an adequate number of minutiae points may be unreadable. it is advised
to issue a secret password or an rFid card for those users whose fingerprint images lack sufficient minutia points
and cannot be read by the sensor. safescan TA-955 has an integrated card reader if you do not intend to assign
passwords.
Figure A-2 shows poor-quality fingerprints, characterized by smudged, faded or distorted areas on the fingerprint.
These conditions can be caused by excessive dryness, wetness, insufficient pressure.
The safescan TA-900 series fingerprint matching algorithm is capable of extracting the cor-rect minutiae without the
benefit of a perfect print. however, the positioning of the finger and the moisture and pressure of the fingerprint are
significant factors to consider when it is placed on the sensor. This will help achieve a good consistent fingerprint
match.
13.3 Correcting Wet or Dry Fingerprint Images
When the temperature is rigid or when hands have just been washed, fingerprints often be-come very dry. in this
case, the user should moisturize his/her fingerprint simply by breathing on the fleshy pad of his/her fingertip prior
to placing his/her finger on the sensor. The moisture from his/her breath should improve the recognition of his/her
fingerprint.
conversely, if the fingerprint is too wet, the ridges and valleys are rendered indistinguishable. The lack of recognizable
minutiae causes wet fingerprints to be rejected by the safescan TA-900 series. This can be remedied simply by
swiping the finger on a clean dry towel or cloth.
how much pressure is required for a good-quality fingerprint?
if too much pressure is applied when pressing down on the sensor, the finger’s ridges become pressed together and
create an unrecognizable image. Applying too much pressure (similar to fingerprints that are too wet) will create a
“blurred” image which the safescan TA-900 series sensor might not recognize.
if too little pressure is applied, the resulting image will be similar to the dry fingerprint and unidentifiable. issues
related to moisture and pressure can easily be addressed with practice and users getting a feel of the sensor.
Figure A-2