Presented at ICITA 2013, 8th International Conference on Information Technology and Applications, Sydney, Australia, 1 - 4 July, 2013 The amount of time taken to enroll or collect data from a subject in a fingerprint recognition system is of paramount importance. Time taken directly affects cost. A trade-off between number of impressions collected and number of interaction attempts allowed to submit those impressions must be realized. In this experiment, data were collected using an optical fingerprint sensor. Each subject submitted six successful impressions with a maximum of 18 interaction attempts. The resulting images were analyzed using three methods: the number of interaction attempts per finger, quality differences from the first three impressions to the last three impressions, and finally matching performance from the first three impressions to the last three impressions. The right middle finger seemed to have the most issues collecting as it required the most interaction attempts. Analysis was performed to show no significant differences in image quality or matching performance. However, after further analysis, a steady improvement was noticed from Group A to Group B in both image quality and matching performance.

1. BIOMETRICS LAB
Biometric Standards, Performance and Assurance Laboratory
Department of Technology, Leadership and Innovation
07/02/2013
Jacob A. Hasselgren, Stephen J. Elliott, Jue Gue
TRADEOFF BETWEEN
IMPRESSION NUMBERS
AND ATTEMPT NUMBERS

2. AGENDA
• Introduction
• Methodology
• Results
• Lessons learned
• Next steps

3. INTRODUCTION
• Many factors can impact the
performance of a biometric system from
poor quality data [1]:
– Skin conditions [2]
– HBSI [3]
– Associated meta-data [4]
• Collect appropriate data and minimize
time/error

4. MOTIVATION
• The efficiency of a biometric system is
important
• While investigating habituation of
biometric systems, the issue of the
proper number of impressions collected
and time arose

5. MOTIVATION
• We collect everyday – at what point do
you stop collecting from a subject?
– 3 samples?
– 6 samples?
– 9 samples?
• We cannot keep subjects forever due to
time and costs

6. MOTIVATION
• Number of subjects is important
• Must design protocol to keep costs low
while still processing as many subjects
as possible
• How many impressions should be
collected from each subject?
• How many attempts should be allowed?
• Which fingers should be collected?

7. QUESTIONS
• Are some fingers harder to collect?
– Do some take longer?
• Is the image quality of the first three any
different from the last three?
• Does the performance change when
slicing groups taken from subjects?
– ie. Do the first three impressions match well
against the last three impressions of the
same subject?

8. DATA
• Collection of multimodal
samples
• Only data from one
fingerprint sensor is be
used for analysis
• U.are.U 4500
• Taken from ongoing aging study in the
BSPA Labs

9. DEFINITIONS
Term Meaning
SAS Successfully acquired sample,
synonymous with impression
Impression number Number given to each SAS, ranging
from 1-6
Interaction attempt number Number given to each interaction
attempt, whether it results in success
or failure, ranging from 1-18

10. BIOMETRICS LAB
Biometric Standards, Performance and Assurance Laboratory
Department of Technology, Leadership and Innovation
METHODOLOGY

11. METHODOLOGY
• 6 impressions/SAS were taken on each
finger with a maximum of 18 interaction
attempts to do so
• Fingers used:
– Left index
– Left middle
– Right index
– Right middle

12. METHODOLOGY
• An impression number was given to
each SAS in order for each finger
– Six impressions per finger, impression
numbers range 1-6
• An interaction attempt number was given
to each interaction attempt in order for
each finger
– Max of 18 interaction attempts was given to
submit 6 SAS’s, intearction attempt numbers
range 1-18

13. METHODOLOGY
• A number of approaches were used to
analyze the samples
– An analysis of the number of attempts
required for each finger
– Compare quality scores between designated
groups (first three, last three)
– Compare matching rates between same
designated groups

14. BIOMETRICS LAB
Biometric Standards, Performance and Assurance Laboratory
Department of Technology, Leadership and Innovation
RESULTS

15. NUMBER OF INTERACTION
ATTEMPTS
• A comparison of the number of SAS’s to
the number of interaction attempts was
performed
• Each subjects submitted six SAS’s
• Did any given finger require more
interaction attempts than others?

16. NUMBER OF ATTEMPTS

17. NUMBER OF ATTEMPTS
• No significant difference between the
fingers was found
• The right middle finger seems to have
the most interaction attempts of all of the
fingers collected
– As well as the most variance

18. DISTRIBUTION OF QUALITY
• A comparison of the first three collected
samples for any given finger to the last
three was performed to find differences
in image quality

19. DISTRIBUTION OF QUALITY
• All of the samples were pushed through
a quality scoring algorithm, Aware WSQ
1000
• Scores a number of different metrics,
with an overall quality score
• This overall quality score was used in the
following analysis

20. DISTRIBUTION OF QUALITY

21. DISTRIBUTION OF QUALITY
• A one-way ANOVA was used to compare
the first three SAS to the last three
• No finger showed a significant difference
Finger P-Value
RI 0.155
RM 0.460
LI 0.090
LM 0.050

22. MATCHING PERFORMANCE
• A comparison of the first three collected
samples for any given finger to the last
three was performed to find differences
in matching performance

23. MATCHING PERFORMANCE
• The samples were enrolled into a
minutiae-based matching
software, Megamatcher 4.3
• The first three SAS’s and last three
SAS’s were enrolled separately
• Equal error rates were used for results

24. MATCHING PERFORMANCE
Finger First 3 vs First 3 Last 3 vs. Last 3 First 3 vs. Last 3
LI 0.0000 0.0000 0.0006
LM 0.3322 0.0000 0.1282
RI 0.0000 0.0000 0.0000
RM 0.0000 0.0000 0.0000

25. MATCHING PERFORMANCE
• No improvements were noticed in
performance for any fingers except for
left middle
– The EER improves from .3322 to .0000

26. BIOMETRICS LAB
Biometric Standards, Performance and Assurance Laboratory
Department of Technology, Leadership and Innovation
LESSONS LEARNED

27. LESSONS LEARNED
• No issues were found when comparing
the number of interactions attempts
between fingers
– Though, right middle finger may require
more attempts to collect impressions
• To save time and unnecessary costs, it
may not be practical to collect additional
samples
– No significant improvement was found after
collecting three additional samples

28. BIOMETRICS LAB
Biometric Standards, Performance and Assurance Laboratory
Department of Technology, Leadership and Innovation
NEXT STEPS

29. NEXT STEPS
• Replicate this study on more sensors
• Attempt to observe habituation using
more than one visit
– Observe effect of habituation on attempt
numbers
• Include time-on-task to get a true
estimation on time required to collect
SAS
• Include hand dominance in interaction
attempts

30. BIOMETRICS LAB
Biometric Standards, Performance and Assurance Laboratory
Department of Technology, Leadership and Innovation
QUESTIONS?
jahassel@purdue.edu