Constructor Detail

• FingerprintMatcher

  public FingerprintMatcher()

  Instantiates an empty fingerprint matcher. Empty matcher does not match any FingerprintTemplate passed to match(FingerprintTemplate). You can call index(FingerprintTemplate) to index probe fingerprint and match(FingerprintTemplate) to match it to some candidate fingerprint.

  See Also:

  index(FingerprintTemplate)

Method Detail

• transparency

  @Deprecated
  public FingerprintMatcher transparency(FingerprintTransparency transparency)

  Deprecated. 
  Enables algorithm transparency. Since FingerprintTransparency is activated automatically via thread-local variable in recent versions of SourceAFIS, this method does nothing in current version of SourceAFIS. It will be removed in some later version.

  Parameters:

  transparency - target FingerprintTransparency or null to disable algorithm transparency

  Returns:

  this (fluent method)

  See Also:

  FingerprintTransparency

• index

  public FingerprintMatcher index(FingerprintTemplate probe)

  Builds search data structures over probe fingerprint template. Once this method is called, it is possible to call match(FingerprintTemplate) to compare fingerprints.

  This method is heavy in terms of RAM footprint and CPU usage. Initialized FingerprintMatcher should be reused for multiple match(FingerprintTemplate) calls in 1:N matching.

  Parameters:

  probe - probe fingerprint template to be matched to candidate fingerprints

  Returns:

  this (fluent method)

  Throws:

  NullPointerException - if probe is null

  See Also:

  match(FingerprintTemplate)

• match

  public double match(FingerprintTemplate candidate)

  Matches candidate fingerprint to probe fingerprint and calculates similarity score. Candidate fingerprint in candidate parameter is matched to probe fingerprint previously passed to index(FingerprintTemplate).

  Returned similarity score is a non-negative number that increases with similarity between probe and candidate fingerprints. Application should compare the score to a threshold with expression (score >= threshold) to arrive at boolean match/non-match decision. Threshold 10 corresponds to FMR (False Match Rate, see Biometric Performance and Confusion matrix) of 10%, threshold 20 to FMR 1%, threshold 30 to FMR 0.1%, and so on.

  Recommended threshold is 40, which corresponds to FMR 0.01%. Correspondence between threshold and FMR is approximate and varies with quality of fingerprints being matched. Increasing threshold rapidly reduces FMR, but it also slowly increases FNMR (False Non-Match Rate). Threshold must be tailored to the needs of the application.

  This method is thread-safe. Multiple threads can match candidates against single FingerprintMatcher.

  Parameters:

  candidate - fingerprint template to be matched with probe fingerprint indexed by this FingerprintMatcher

  Returns:

  similarity score between probe and candidate fingerprints

  Throws:

  NullPointerException - if candidate is null

  See Also:

  index(FingerprintTemplate)