Conformance to Standardized Minutia 

Detection Requirements 

Christoph Busch and Sebastian Abt 

Hochschule Darmstadt 

Center for Advanced Security Research Darmstadt 

IBPC 2012 

NIST - March 6-8,.2012 
Conformance to Standardized Minutia Detection Requirements 

MOTIVATION 

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Motivation 

1. Fingerprint 

image (biometric 

sample) after 

acquisition as 

generated by 

capture device. 

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Minutiae Templates 

2. Features 3. Biometric template encoding. 

(minutiae) as According to ISO/IEC 19794-2: 

identified during 1. Minutia x-coordinate 

feature 2. Minutia y-coordinate 

extraction 3. Minutia angle θ

process. 4. Minutia type t 

5. Minutia quality q 

Ridge line endinge Ridge line bifurcation 

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Motivation 

Minutiae Detection Deficiency 

Vendor A 

Vendor B 

Vendor C 

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Motivation 

Minutiae Misplacement 

• MINEX results presented at BIOSIG 2009 

– 2D histogram of minutiae locations 

– Angle and type information ignored 

(Source: Tabassi et al., BIOSIG2009) 

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Motivation 

Conformance Testing 

• ISO/IEC 29109-x: Conformance testing 

methodology for biometric data 

interchange formats defined in ISO/IEC 

19794-x: 

– Level 1: Data format conformance 

– Level 2: Internal consistency checking 

– Level 3: Content checking 

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Motivation 

Conformance Testing 

• ISO/IEC 29109 - Part2: Finger minutiae data 

• ISO/IEC 29109-2 AMD1: Semantic conformance 

testing - Part2: Finger minutiae data 

- Scope: tests of semantic assertions 

Type A Level 3 as defined in ISO/IEC 29109-1:2009 

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March 8, 2012

Motivation

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• ISO/IEC 29109-2 AMD1:

• „The reason these tests are necessary is because in 

practice minutia detectors sometimes 

• fail to properly place a minutia

• detect a false minutia within the ridge structure of a 

 parent fingerprint; 

• detect a false minutia outside or at the periphery of 

 an image of the parent fingerprint

• fail to detect a minutia within the fingerprint data

• fail to determine type correctly 

• fail to measure angle correctly „

Conformance Testing
March 8, 2012

Motivation

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• ISO/IEC 29109-2 AMD1 (SC37N4834):

• Clause 7.4 Minutiae conformance measure

• Clause 7.5 Out-of-area test

• Clause 7.6 False minutia test

Conformance Testing
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Conformance to Standardized Minutia Detection Requirements

REVISED PERSECTIVE ON

SEMANTIC CONFORMANCE TESTING

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March 8, 2012

• Level 3: Content checking

– „to test that the BDIRs produced by an IUT are faithful 

representations of the original biometric data and that they satisfy 

those requirements of the base standard that are not simply a matter 

of syntax and format [...]“ (ISO/IEC 29109-1)

• Strict (loose) definition of ‚faithfulness‘ 

– „A biometric template resulting from a noise-free and linear 

transformation applied to the input biometric charachteristic‘s 

(sample‘s) traits.“

– Faithfulness in strict sense desired

– Faithfulness in loose sense measured, due to non-linear physical 

effects during data acquisition

Semantic Conformance Testing

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Minutiae Sets
• Faithfulness 

– Modeled as continuous function 

– With reference set and test set

– Measured at minutiae-level

• Per attribute equality

• No addition of spurious minutiae

• Computation Model 

– For a set of feature extractors 

– compute conformance rates 

– based on a reference data set 

– and on definition of faithfulness 

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Semantic Conformance Testing

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Formalisation

Ri 

"
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Semantic Conformance Testing

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• Ground-Truth Minutiae 

• Consists of triplets

– Biometric sample

– Reference template

– Weight

• Based on biometric samples of NIST special databases SD14 and SD29

• Samples manually analyzed by dactyloscopic experts of BKA

➥ Results in a scattered set of ground truth minutiae per biometric sample

➥ Sample fusion?

Reference Data Set
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Semantic Conformance Testing

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• Explicit Fusion Methodology

– Requires explicit data fusion process

– Computes harmonized samples from scattered expert data - see

a) presentation at IBPC 2010: 

http://biometrics.nist.gov/cs_links/ibpc2010/pdfs/Busch_Christoph_IBPC2010-gtm-100224.pdf

b) presentation by Sebastian Abt at BIOSIG 2010: 

http://www.christoph-busch.de/files/Abt-FingerMinutiaeClustering-BIOSIG-2010.pdf

• Implicit Fusion Methodology

– Implicit fusion during conformance rate computation 

where references Rkd are generated by d=1,...,D dactyloscopic experts

– Requires adjusted weights

– Uses scattered samples as-is

• Known-Truth Methodology

– Utilizes synthetically generated data

Testing Methodologies
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Semantic Conformance Testing

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• Minutiae quality scores

– Valued 0 ≤ q ≤ 100 according to ISO/IEC 19794-2

– Can be interpreted as confidence value

– Usage of minutiae quality is controversially discussed in SC37

as no standardized method for determination exists

– However, standardization of minutiae quality not required

• Quality-score honoring instance 

• Function to measure faithfulness 

– Addresses minutiae misplacement and

– spurious minutiae placement problems

– Honores minutiae quality values

A Quality-score Honoring Approach
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Semantic Conformance Testing

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• Quantifies degree to which automatically generated minutiae deviate from 

ground-truth minutiae

• Equally penalizes location, angle and type differences

• Penalty weighted according to minutiae reliability

Minutiae Misplacement Problem
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Semantic Conformance Testing

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• Compute ratio of spurious minutiae 

- no distinction between „out of fingerprint area“ and „inside“

• Weighted according to minutiae reliabilities

Spurious Minutiae Problem

reference minutiae

spurious minutiae

mated minutiae
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Assessing Semantic Conformance of Minutiae-based Feature Extractors

EVALUATION AND RESULTS

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Evaluation and Results

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• Development of feature extractors and comparators using 3 SDKs

• Computation of 162 DET curves

• Analysis of 3294 biometric samples

• Creation of 12661 biometric templates

• Computation of 34,6M comparison scores

Environment
March 8, 2012

Evaluation and Results

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• Comparison of CRs and avg. non-native equal error rates (nnEER)

• nnEER estimate of real-world inter-vendor performance:

– Average of equal error rates in non-native case,

– i.e. using probe templates from Vx and reference templates from Vy

Real World Correlation
March 8, 2012

Evaluation and Results

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• Comparison of CRs and avg. non-native equal error rates (nnEER)

• nnEER estimate of real-world inter-vendor performance:

– Average of equal error rates in non-native case,

– i.e. using probe templates from Vx and reference templates from Vy

• Benchmarked using non quality honoring approach (SCMBL) described in

– Lodrova, Busch, Tabassi, Krodel, Drahansky. „Semantic Conformance Testing 

Methodology for Finger Minutiae Data“. In Proceedings of BIOSIG, 2009.

Real World Correlation
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Evaluation and Results

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• Evaluation of implicit vs. explicit fusion methodologies

• Evaluation shows that both methodologies lead to comparable results

➥ Explicit clustering not necessary!

Testing Methodologies
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Assessing Semantic Conformance of Minutiae-based Feature Extractors

CONCLUSION AND FUTURE WORK

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Conclusion and Future Work

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• Semantic conformance computation 

based on formal definition of faithfulness

• Plausibility testing yields reasonable results

• Conformance rates of quality honoring approach correlate

with real-world inter-vendor performance estimates

• Explicit clustering not necessary

• Contribution

– Integration of ideas into ISO/IEC 29109-2 AMD1

– Abt, Busch, Baier. „A quality-score honoring approach to semantic 

conformance assessment of minutiae-based feature extractors“. In 

Proceedings of BIOSIG 2011, pp. 21-32, 2011. 

A copy is available at: 

http://www.christoph-busch.de/standards-gtd.html

Conclusion and Contribution
March 8, 2012

Conclusion and Future Work

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• ISO/IEC 29109-2 AMD1 requires further contributions

• What is a common definition of a markup?

a) an automated SDK generated minutia?

b) a minutia generated by an individual

 (i.e. a dactyloscopic expert)

c) any minutiae either a) or b)

• Need for Semantic Conformance Computation Challenge (SC3)

- Stronger evaluation (more templates and algorithms) 

- in cooperation with NIST

Future Work
March 8, 2012

Thanks to...

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Elham Tabasssi

Martin Olsen

Patrick Grother

Raffaelle Cappelli

Timo Ruhland

Wolfgang Krodel
March 8, 2012

Thank you!

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Questions?

Discussion!
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Questions?

Discussion!

Contact