Instructions

U.are.U SDK - Developer Guide 80
Application Notes
THIS CHAPTER DESCRIBES SOME SUGGESTIONS FOR TROUBLESHOOTING YOUR APPLICATION.
General Fingerprint Issues
It is very important that you test your application with multiple and diverse people. The readability of fingerprints is
affected by many factors including wear and tear, skin dryness, and age.
The middle finger often gives better scans than the index finger because the middle finger is typically less worn. We
recommend that you enroll more than one finger for each user, preferably at least the index and middle fingers.
Minex Certification
This current U.are.U SDK includes two versions of the FingerJet matching engine, versions 6 and 7.
Version 6 has a feature extractor certified by the National Institute of Standards and Technology’s Minex program
(http://www.nist.gov/itl/iad/ig/minex.cfm
), as interoperable with other Minex-certified feature extractors and matchers.
Version 7 has both the feature extractor and matcher certified by the Minex program. However, the Minex-certified
matcher is slower than the non-certified matcher in the version 6 FingerJet engine.
For customers who do not have a requirement to use a Minex-certified matcher, we recommend using the version 6
FingerJet engine. Specifically, for customers who use DigitalPersona legacy template formats, the version 7 FingerJet
engine does not provide any improvements in matching performance over version 6.
C/C++ Issues
The dpfj_identify function returns DPFJ_SUCCESS if it is able to do identification (i.e., the FMDs are valid and
correctly formed). However that does not mean that a candidate was found. You must check the number of returned
candidates to see if any actual matches were found.
The
dpfj_compare function returns DPFJ_SUCCESS if it is able to do the requested comparison (i.e., the FMDs are
valid and correctly formed). However that does not mean that the fingerprints matched. To check whether they
matched, you must look at the dissimilarity score (0=no match,
maxint =perfect match, maxint-threshold =
acceptable match).