Instructions

U.are.U SDK - Developer Guide 32
The JAVA API
of setting the threshold as well as the statistical validity of the dissimilarity score and error rates, consult NIST
Fingerprint Image Quality (NFIQ) on page 14
.
Compare() takes two single views from two FMDs and returns a dissimilarity score indicating the quality of the
match.
The majority of applications should use the Identify method to implement both identification and verification.
However, in a few special cases, e.g., using multi-modal biometrics, or doing statistical risk assessment, the Compare
method allows you to compare two FMVs to determine their actual degree of dissimilarity. This is useful for accuracy
testing and diagnostics and is not intended to be used in final applications for actual fingerprint recognition. The
Compare method returns a dissimilarity score with values:
• 0 = fingerprints are NOT dissimilar (i.e., they MATCH perfectly).
• maxint (#7FFFFFFF or 2147483647) = fingerprints are completely dissimilar (i.e., DO NOT match).
• Values close to 0 indicate very close matches, values closer to maxint indicate very poor matches.
The table below shows the relationship between the scores returned from Compare and the false match error rates
observed in our test. The dissimilarity score distribution is estimated based on our internal testing, and may not be
representative of the actual rate that will be observed in deployment.
Enrollment
CreateEnrollmentFmd() creates and returns an enrollment FMD. It takes as input a reference to an object of
type EnrollmentCallback. The client must implement EnrollmentCallback.GetFmd(). This method
acquires and returns an FMD to add to the enrollment. The engine calls EnrollmentCallback.GetFmd() as
many times as needed in order to create an enrollment FMD.
Normally, the client application will implement EnrollmentCallback.GetFmd() to provide the onscreen UI
to capture fingerprints from the reader, extract features using CreateFmd(), and return an enrollment FMD. If the
user wants to cancel the enrollment, EnrollmentCallback.GetFmd() should return null.
Dissimilarity Score False Match Rate
2147483
.1%
214748
.01%
21474
.001%
2147
.0001%
Function Description
Compare Compare two FMDs; supported formats are: Gold SDK, One Touch SDK, ANSI
and ISO.
Identify Identify an FMD: given an array of FMDs, this function returns an array of candi-
dates that match the original fingerprint (an FMV within an FMD) within the
threshold of error. Supported formats are: Gold SDK, One Touch SDK, ANSI and
ISO.