Minutiae Interoperability Exchang

(MINEX) 

An Evaluation of the INCITS 378 

Fingerprint Minutiae Templates 

Patrick Grother 

NIST 

IAI :: AFIS Committee Meeting 

NIST, February 28, 2007 
Overview of Talk 

• MINEX primer • MINEX major results • Recent results • Toward an explanation • Recent minutia standardization activ• Conclusions 
MINEX Overview 

• INCITS 378 standard templates 

• MIN:A templates 

• encodes coordinates (x, y), angle 

(θ), type, (no quality) 

• MIN:B templates 

• MIN:A data plus ridge count, 

core, and delta information 

• Proprietary templates 

• Individual vendor’s 

representation of images 

• Performance test 

• Interoperable performance is 

stated in terms of verification accuracy (FNMR vs. FMR) 

• 4 datasets 

• POEBVA, DHS2, P• Left and right index 

• Test size 

• 493418 match “ge

comparisons 

• 975890 non-match 

comparisons 

• Multiple vendors 

• 14 vendors in prop• 14 vendors in MIN• 6 participants in M

• Largest test ever co

• Cubic complexity • 4.4 billion compari
MINEX Purpose 

• MINEX is intended 

• To assess performance of the new INCITS 378 

• INTEROPERABILITY - to assess core capability of 

matching standard templates against those generatesuppliers’ implementations 

• Template “competence” 

• SUFFICIENCY - to compare performance of algorit

on standardized vs. proprietary (i.e. image-based) te

• MINEX is not intended 

• To predict performance of PIV, TWIC, RT ... 

• Why not? Actual performance is dependent on envir

habituation, multiple attempts ... 
Three way interoperabili

Vendor B 

Matcher 

Enrolment Template 

Produced by Vendor A 

Authenticatio

Produced b

similarity score 

Repeat this for all 143 supplier triplets, a

genuine and impostor comparisons 

Measure Performance 
Native vs. Proprietary 

False NonMatch Rate at Supplier of Template Matc

False Match Rate of 0.01 

MINEX 

Vendors Proprietary Na

Sta

Supplier of Enrollment 

Template 

Vendor A 0.0047 0.0Vendor B 0.0089 0.0

Vendor C 0.0089 0.0

PROPRIETARY Representation of the template is completely unconstrained

Construe it to be the supplier’s “best effort maximum accura

NATIVE Representation of the template is constrained by the INCITS 

One supplier generates and matches the template. 
Performance Interoperabi

False Non-Match 

Rate at False 

Supplier of Verificatio

Template + Template Ma

Match Rate of 0.01 Vendor A 

Supplier of Enrollment 

Template 

Vendor A 0.0129 

Red values refer to NATIVE performance : One vendor generates and matches all templates. 
Performance Interoperabi

False Non-Match 

Rate at False 

Supplier of Verificatio

Template + Template Ma

Match Rate of 0.01 Vendor A Vendor B 

Supplier of Enrollment 

Template 

Vendor A 0.0129 0.0205 Vendor B 0.0316 0.0140 

Red values refer to NATIVE performance : One vendor generates and matches all templates. 
Performance Interoperabi

False Non-Match 

Rate at False 

Supplier of Verificatio

Template + Template Ma

Match Rate of 0.01 Vendor A Vendor B Ven

Supplier of Enrollment 

Template 

Vendor A 0.0129 0.0205 0.0

Vendor B 0.0316 0.0140 0.0

Vendor C 0.0417 0.0225 0.0

Red values refer to NATIVE performance : One vendor generates both templates and matches them. 
Interoperability :: Scenario 

Vendor makes enrollment template and executes the comp

Vendor makes enrollment template 

Diagonal elements are usually smallest Within-vend

operation is superior to interoperable 

Single finger, POEBVA dataset, FNMR at FMR = 0.01 
PIV 

• MINEX is being used by GSA as one crite

PIV 

• MINEX Report 2006 formed initial interoperab• Ongoing MINEX testing allows others in. • Minutiae encoders qualify if their output temp

be matched by all matchers with FNMR < 0.0FMR = 0.01 using two fused fingers 

• In all cases, matchers qualify if they compare 

suppliers’ templates with FNMR < 0.01 at FMusing two fused fingers 
MINEX Eligible for GSA 

• Template Generators • Cogent Systems • Dermalog Identification Systems • Bioscrypt • Sagem Morpho • Neurotechnologija • Innovatrics • NEC • Cross Match Technologies • L1 / Identix • Precise Biometrics • XTec • SecuGen • BIO-key International • Motorola • Aware • Sonda Technologies 

16 suppliers 

• Matchers • Cogent Systems • Dermalog Identification • Bioscrypt • Sagem Morpho •• Innovatrics • NEC •• L1 / Identix •• XTec • SecuGen • BIO-key International • Motorola • Startek Engineering • Sagem Morpho (MOC

12 suppliers 
INCITS 378 Conformance Cla

2 Conformance A system conforms to this standard if satisfies the mandatory requirements for extraction of minutiae from a fingerimage as described in Section 5 and tgeneration of a minutiae data record adescribed in Section 6. 
INCITS 378 on Placeme

2004 :: 5.3.2 Minutia Placement on a Ridge Ending The minutia for a ridge ending shall be defined as the point of forkinmedial skeleton of the valley area immediately in front of the ridge evalley area were thinned down to a single-pixel-wide skeleton, the pthe three legs intersect is the location of the minutia. In simpler termwhere the valley “Y”s, or (equivalently) where the three legs of the tvalley area intersect. 2007 :: 5.3.2 Minutia Placement on a Ridge Ending The minutia for a ridge ending shall be defined as the point of forkinmedial skeleton of the valley area immediately in front of the ridge evalley area were thinned down to a single-pixel-wide skeleton, the pthe three legs intersect is the location of the minutia. In simpler termwhere the valley “Y”’s, or (equivalently) where the three legs of the valley area intersect. A Ridge Ending shall be encoded only if all of used to calculate the minutiae angle length (as defined in 5.4.2 – AnRidge Ending) are greater than or equal to 0.02 inches in length. 

The standards contain analogous text for bifurcations also. 
Minutiae from two produc

Insertion / Deletion 

Angle Difference 

Angle, position and type Differences 
2D Minutiae Density 

Intensity, 

I(x, y), is 

to the estimated la minutiae will be template generatoNo registration apNo consideration type, class, or quaEach 2D density festimated from ~ templates derived 368x368 images using a single moThese effects are other optical sens

Order of appearance is not the alphabetic order of vendors in the MINEX reports 
Performance depends on source 

enrollment and verification templa

“Excess” FNMR = FNMRXYZ – FNMRZZZ 

Verification Template Generator 

Enrollment 

Template 

Generator 

0.014 

= 0.023 – 0.014 

D 

0.023 

Top left portion of Table 11a in NIST IR 7296. Scenario 2. Matcher D. 
Interoperability Models 

Regression Models 

When matcher Z compares templates from generators A and produces an “excess” error over it’s native performance. 

Model 1 FNMRABZ – FNMRZZZ ~ RegionalOverlap(T

A, T

B) + 

NonUniformity(T

A) * NonUniformity

Model 2 FNMRABZ – FNMRZZZ ~ RegionalOverlap(T

A, T

B) + Matcher 

NonUniformity(T

A) * NonUniformity

where RegionalOverlap(T

A, T

B) = P

A(x, y) . P

B(x, y) (i.e. 

PB = Estimated 2D PDF for template generator B

A measure of similarity between where A and B are finding m

and NonUniformity(T

A) = Energy( HighPassFilter(P

A(x, y)) ) 

A scalar measure of local non-uniformity in minutiae occurrehere as a proxy for minutiae location quantization. 
Non-uniformity as Proxy fo

Minutiae Misplacement 

Establish a scalar proxy of the degree to which unexpected regupatterns exist in the PDF. 

false color original 

Local no0.011 

original high pass filtered 

Local no0.029 
Interoperability Models :: Res

• Model 1: Adjusted R2 = 0.49 

• Model 2: Adjusted R2 = 0.60 • Non-uniformity (high frequency content) positively contrib

“excess” FNMR 

• Non-uniformity in both the enrollment and verification tem

negatively contributes to FNMR 

• Regional overlap negatively contributes to “excess” FNMR • The matcher significantly contributes to “excess” FNMR, p

and negatively 

• All effects above are strongly significant • The regression is imperfect 

• There are missing explanatory variables (minutiae angle enc

differences and other). 
Standards Activity INCITS 

• A revision of INCITS 378 is progressing thr

• Posted as M1/06-0680, September 13 2006 

• It includes refined guidance on minutia plac
Standards Activity 19794

Text from New Work Item Proposal: SC37N1656 

Approved per National Body vote Sep 14: SC37N1787 

Scope The scope of the proposed new work item is to standardise method

binarisation of gray-scale finger images, for the thinning of ridges (skeletonisation), and for the extraction of location, direction, and tyminutiae from ridge skeletons. Purpose and Justification Interoperability tests have shown that the location, the direction, and minutiae extracted by different minutiae extraction subsystems from finger image tend to be different. This is due to supplier-specific improcessing algorithms. However, in order to achieve interoperability subsystems from different suppliers, it is important that the individuaextraction algorithms yield matchable minutiae. This can be achievstandardising a minutiae extraction method. The results obtained frminutiae extraction algorithms can then be compared to a well-defintruth, which is obtained by applying the standard minutiae extraction This would allow the suppliers to compensate for any biases that thextraction algorithms may produce. 
Conclusions 

• FNMR is lowest when both templates and the mat

from the same supplier (“native”) 

• FNMR is lower when both templates come from on• Template generation is idiosyncratic • Syntactic conformance is not enough for interoper• Some template generators are semantically non-c

• Non-conformance is evident in the 2D minutiae occurren

• Such non-conformance degrades interoperability • Single image-template analysis is necessary to ex

empirical MINEX results further 

• Extraction algorithm standardization should embed • Offline technology testing is suited to measuremen

algorithmic interoperability 
Thank you 

The MINEX report is online 

http://fingerprint.nist.gov/minex04/ 

Ongoing MINEX program 

http://fingerprint.nist.gov/minex 

Feedback will be welcomed. 

For further information contact 

patrick.grother@nist.gov