March 2010 – International Biometrics Performance Conference 1 

Recognition Performance 

in the Case of Juvenile Fingerprints 

Günter Schumacher 

European Commission Joint Research Centre (JRC) 

Institute for the Protection and Security of the Citizen (IPSC) 

Security Technology Assessment Unit (STA) 
Motivation 

March 2010 – International Biometrics Performance Conference 2 

• Children yet to be excluded when it comes 

to verification against templates older than 

1 or 2 years: 

• Children <12 currently not fingerprinted for 

neither EU passport nor Visa Information System 

• Parliament and EDPS not convinced about 

feasibility and accuracy performance 

• Identification and verification to be guaranteed

over time, given the validity of an enrolment for 

about 5 years 

• Biometric verification can be expected 

•to impede child trafficking 

•to reduce abuse of children for fraud 

•to help identifying missed children 
Current Situation 

March 2010 – International Biometrics Performance Conference 3 

• Matchers do not directly take into account the growing of 

the ridge pattern 

• Resolution of scanners and assumptions about dimension 

of ridge structure is another obstacle 

• Children fingerprinting exists only for documentation 

purposes but is hardly applicable to AFIS 

→ Dedicated feasibility study 

more than overdue ! 

Source: Anthony's Mobile Fingerprinting 
More detailed view on images 

March 2010 – International Biometrics Performance Conference 4 

6 years 

12 years 

• Ridge distance of 6 years old only half of 

adults: from ~10 pixels down to ~5 pixels 

[@500dpi] 

• Likelihood of low contrast regions 

increase 

• Quality metrics (like NFIQ) not trained for 

juvenile fingerprints 
NFIQ: Examples from BIODEV* 

March 2010 – International Biometrics Performance Conference 5 

*BIODEV = European study on operational aspects of 

visa application including biometric enrolment 
Why normal matchers fail 

March 2010 – International Biometrics Performance Conference 6 

Time = T0 Time = T1, T1 >>T0 

Difficulties in getting “still” images 

Contrast problems 

Wrong assumption about ridge distance 

Local features displacement beyond 

accepted level of “distortion” 
Acquisition 

March 2010 – International Biometrics Performance Conference 7 

• Can be extremely difficult to enrol young children because 

of inadequate scanning device and overall setup 

• Need for manual help by an operator is disputable 

• Time to enrol can be acceptable for first enrolment but can 

be inacceptable for verification 

• Enrolment should become more 

tolerant against movements 

• Touchless sensors (“on the fly”) 

could become the ultimate choice 

Image: Ultimate Woodlands 
Contrast 

March 2010 – International Biometrics Performance Conference 8 

• Imprint distance between ridge lines can be down to 0.1 mm 

(= 2 pixel @ 500 dpi) for adults! 

• Proper acquisition process can partially avoid this 
Image processing 

March 2010 – International Biometrics Performance Conference 9 

NIST mindtct finds 

• 107 minutiae 

• 15 minutiae have 

reliability score > 0.8 

Raw Image Pre-Processed 

Example: Age = 6, NFIQ = 4 
Matching 

March 2010 – International Biometrics Performance Conference 10 

• Matching should establish a 

similarity score between a template 

and a (kind-of) “zoomed” image 

• Not yet clear whether “zooming” is 

linear or subject to significant 

distortion 

• Feature extraction is usually not the 

same for different zooming levels of 

an image 

• Not only minutiae positions are 

considered 
 

 

 

Further facts 

March 2010 – International Biometrics Performance Conference 11 

• 500 dpi images of very young children can be excellent 

→ Elaboration on relevant conditions necessary 

• Some vendors have already introduced ridge distance 

adoption and experimented with assumed ageing 

→ Feedback to vendors on measured growing effect 

• Yet no statistics available on recognition performance 

against aged templates in case of juveniles 

→ Need for a test database with significant time period 

between enrolments of individual juvenile test subjects 
Roadmap for the study 

March 2010 – International Biometrics Performance Conference 12 

• Find best practice how to acquire images of sufficient 

quality 

• Approximate ridge distance growing curve and use this for 

enhanced feature extraction 

• Use test database to measure local feature displacement 

and degree of deviation from pure affine transformation 

• Cooperate with vendors for introducing “juvenile feature” 

• Use test database to measure performance of enhanced 

matchers 

• Derive overall feasibility conclusion 
Conclusions 

March 2010 – International Biometrics Performance Conference 13 

• Automated verification and identification of children 

fingerprints likely to be feasible in practice at acceptable 

performance level 

• Feasibility question will be tackled in several tasks: 

• Physiological effects 

• Enrolment best practices 

• Algorithmic enhancements 

• Performance test on large data sets 

• Preliminary results might become available by end of 2010 
March 2010 – International Biometrics Performance Conference 14 

Contact: 

Dr. Günter Schumacher 

Guenter-Egon.Schumacher@jrc.ec.europa.eu