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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Evaluation of Quality Features 

for NFIQ 2.0 

Johannes Merkle 

secunet Security Networks 

Page: 2

IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Considered Features (1) 

• NFIQ1 quality features 

• Foreground (FG) 

• Number of minutiae (NoMin) 

• Minutiae (minimum) quality count (min05, min06, min075, min08, min09) 

• Quality zone (blockwise) count (QZ1, QZ2, QZ3, QZ4) 

• Features derived from digitalPersona FingerJetFX software 

• Minutiae Count (MinCount) • cut-off at 65 

• Minutiae quality (interval) count (MinQual4 – MinQual10) 

• Average minutiae quality (AvMinQual) 
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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Considered Features (2) 

• Quality features from ISO/IEC 29794-4, implemented by hda (Olsen) 

• Frequency Domain Analysis (FDA) 

• Local Clarity Score (LCS) 

• Orientation Certainty Level (OCL) 

• Orientation Flow (OF) 

• (Radial) Power Spectrum (PS) 

• Ridge Valley Uniformity (RVU) 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Considered Features (3) 

• Additional quality features implemented hda Olsen 

• Gabor 

• Gabor Segment (GS) 

• Gabor Shen (GSh) 

• Mu 

• Mu Mu Block (MMB) 

• Mu Mu Sigma Block (MMSB) 

• Mu Sigma Block (MSB) 

• Sigma 

• Sigma Sigma Block (SSB) 
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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Objectives of Evaluation 

• Determine set of features eligible for training of NFIQ2 algorithm 

• Relevance 

• How indicative is the feature for biometric performance of fingerprints 

• Independence: 

• Is the metric redundant with other features? 

• May be good or bad 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Evaluation Methods 

• Spearman (rank) correlation 

• With utility computed from comparison scores acc. ISO 29794-1 

• Utility used as ground truth 

• With other features 

• Measure Impact on biometric performance 

• ROC curve approach: Error rate determination for quality control 

• Error reject curves (ERC): impact of quality filtering to FNMR 
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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Data Basis for Evaluation 

• FingerQS Database 

• Collected in BSI project 

• 79056 fingerprints from 1098 volunteers 

• 8 fingers per individual 

• 9 live scans per finger 

• Taken with 3 different optical sensors 

• Similarity Scores computed with 3 SDKs 

• 8 genuine scores and 60 impostor scores per fingerprint 

• Utility values computed from scores according to ISO/IEC 29794-1 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Correlations NFIQ1 Features 
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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Correlations FJFX Features 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Correlations ISO Features 
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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Correlations other Features 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

ROC Curve Evaluation -Method 

• Simulate biometric application using feature for quality control 

• Select best of 3 impressions during enrolment 

• Realistic scenario: used in enrolment for German visa 

• Compute ROC curve from comparison scores of selected fingerprints 

• No quality control for probe fingerprint 
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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

ROC Curve Evaluation - Results 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

ERC Evaluation -Method 

• Determine impact of quality filtering on FNMR 

• Feature values used as quality indicator 

• Fix operational threshold at certain FNMR 

• Filter genuine comparisons with respect to feature value 

• Neglect scores where value of reference or probe fingerprint is too low 

• Show dependency of FNMR on feature threshold 

• We used FNMR = 3% and FNMR = 10% 

• Can show non-monoton dependency of performance on feature values 
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ERC Evaluation - Results 

FNMR = 3% 

IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle Page: 15 

ERC Evaluation - Results 

FNMR = 10% 

IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle Page: 16 

8 
CASIA Utility 

GSh 0,24 

PS 0,23 

OCL 0,22 

OF 0,22 

Gabor 0,22 

FDA 0,20 

LCS 0,17 

RVU 0,13 

Optical 

FVC2004Db3 Utility 

PS 0,54 

Gabor 0,51 

FDA 0,44

LCS 0,41 

OCL 0,40 

GSh 0,36 

RVU 0,24 

OF 0,24 

Thermal sweeping 

FVC2002Db3 Utility 

PS 0,13 

Gabor 0,12 

RVU 0,11 

OF 0,07 

FDA 0,07 

OCL 0,04 

GSh 0,03 

LCS 0,01 

Capacitive 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Summary of Results 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Additional Evaluation 

• 3 databases with different sensor technologies 

• Comparison scores from other SDK 
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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

Features to be considered for NFIQ2.0 

• From NFIQ1 

• Quality Zone 3 and 4 

• Foreground 

• But: No minutiae-based features 

(computation too slow) 

• From ISO/IEC TR 29794-4 

• Frequency Domain Analysis 

• Local Clarity Score 

• Orientation Certainty Level 

• Orientation Flow 

• Power Spectrum 

• Ridge Valley Uniformity 

• New features 

• Gabor 

• Gabor Segment 

• Gabor Shen 

• Mu Mu Sigma Block 

• Mu Sigma Block 

• From digitalPersona FingerJetFX 

• E.g. Number of Minutiae 

(remove cut-off) 

• E.g. Minutiae quality counts 

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IBPC 2012 / Satellite Workshop on NIFQ 2.0 

NIST Gaithersburg, March 5, 2012 

Johannes Merkle 

secunet Security Networks AG 

Johannes Merkle 

Johannes.merkle@secunet.com 

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