Methods for Quality Determination of Papillary Lines in Fingerprints NIST – Biometric Quality Workshop II, November 7-8, 2007, Gaithersburg, USA Martin Drahansky (www.fit.vutbr.cz/~drahan ) Brno University of Technology, Faculty of Information Technology Bozetechova 2, 612 66, Brno, Czech Republic
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Methods for Quality Determination of Papillary Lines in Fingerprints
NIST – Biometric Quality Workshop II, November 7-8, 2007 , Gaithersburg, USA
Martin Drahansky ( www.fit.vutbr.cz/~drahan )Brno University of Technology, Faculty of Information Technology
Bozetechova 2, 612 66, Brno, Czech Republic
Overview
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� Quality measures derived from the image histogram
� Information entropy in the fingerprint
� Quality estimation of a papillary line
1 – Technologies of Fingerprint Sensors
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Optical Technology
Capacitive Technology
Ultrasound Technology
E-Field Technology
Electro-optical Technology
Pressure Technology
Thermal Technology
Fingerprint Sensor Technologies I.
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� Optical Technology
Protective Glass
Lens
CCD-Camera
Lichtquelle Lichtquelle
Finger
� Capacitive Technology
Silicon Dioxide
↓
Finger
V
δδδδQC1 Cout
V0
~65µ
Metal Plate
Identix
Veridicom
Fingerprint Sensor Technologies II.
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� Ultrasonic Technology
� Electro-optical Technology
xy
T
Isolation Layer
Black Coaxial Layer
Light Emitting Phosphorus Layer
Basic Layer
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Optel
AuthentTec
Fingerprint Sensor Technologies III.
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� Pressure-Sensitive Technology
� Thermal Technology
Finger
Non-Conductive Layer
Electro-Conductive Layer
Insulation Layer
Pyro-electric Cell
Raw Image
Image Reconstruction
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BMF
Atmel
2 – Quality Measures from the Image Histogram
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� Histogram – Example (Suprema SFM 3020 – B&W)
� Histogram – Example (Suprema SFM 3050 – gaps)
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Histogram of a Fingerprint Image I.
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� Histogram – Access Control Systems
� Histogram – Dactyloscopic (Identification) Systems
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Histogram of a Fingerprint Image II.
Quality of Fingerprints I.
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� Image Contrast
� Weber Contrast
� Michelson Contrast
� Average Value of Grayscale (∅ Full G-Scale = 128)
More in: Drahansky, M.: Biometric Security Systems – Fingerprint Recognition Technology, Dissertation, Brno University of Technology, Faculty of Information Technology, 2005
Real Amounts of Minutiae + Entropies
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Amount of minutiae (Bergdata)
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10
User [No]
Num
ber
of m
inut
iae
Maximum Minimum Average
Amount of minutiae (Dactyloscopic)
0
20
40
60
80
100
120
140
160
1 2 3 4 5 6 7 8 9 10
User [No]
Num
ber
of m
inut
iae
Maximum Minimum Average
Amount of minutiae (Veridicom)
0
20
40
60
80
100
120
140
160
1 2 3 4 5 6 7 8 9 10
User [No]
Num
ber
of m
inut
iae
Maximum Minimum Average
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Entropy Computation:
Maximal Entropy (368 minutiae):
Minimal Entropy (12 minutiae):
Quantization = Reduction of Entropy !!!
4 – Quality Estimation of a Papillary Line
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http://162.105.71.163/people/chenxg/fip.jpg
Center Computation I.
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� Finding of Fingerprint’s Center
� Gravity Center of the Minutiae (M1)
� Vertical & Horizontal Maximums of Ridge Count (M2)
� Middle of the Orientation Field (M3)
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CoreCore
DeltaDelta
Type-Lines
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� Finding of Fingerprint’s Center
� Gravity Center of the Minutiae (M1)
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Center Computation II.
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� Finding of Fingerprint’s Center
� Vertical & Horizontal Maximums of Ridge Count (M2)
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37,0031,0051,0024,00Vertical maximum
25,6722,7933,1813,26Vertical average
11,0011,003,005,00Vertical minimum
31,0030,0027,0023,00Horizontal maximum
21,2519,9319,3012,86Horizontal average
10,009,006,006,00Horizontal minimum
050020010000Sensor(Suprema
SFM3xxx)
Center Computation III.
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� Finding of Fingerprint’s Center
� Middle of the Orientation Field (M3)
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Center Computation IV.
Crosscut Through the Fingerprint Image I.
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� Crosscut Through the Fingerprint in the Center
Valley(background)
Ridge(foreground)
� Reason: Perpendicularity of the Cut to Papillary Line
� Same for Horizontal and Vertical Cuts
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Crosscut Through the Fingerprint Image II.
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� Comparison with the Sine Function
� Range:
� Deviation of the Curvature from the Sine Function
2
3,
2
ππ−
sin
1 100%FAA
AD
A
= − ⋅
( )E
S
x
FA
x
A f x dx= ∫ sin sin( )E
S
x
x
A x dx= ∫&…
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Crosscut Through the Fingerprint Image III.
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� Thickness of the Papillary Line
� Deviation of the Thickness from the Defined One (0,33 mm)
[ ]2,54Pix
DPI
Th N cmR
= ⋅
1 100%0,033Th
ThD
= − ⋅
18%
18%
18%
178195 187
5,5 Pixels 8 Pixels 7 Pixels
[ ]2,54Pix
DPI
Th N cmR
= ⋅
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Crosscut Through the Fingerprint Image IV.
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� Steepness of the Papillary Line
� Deviation of the Steepness from Ideal Triangle
Px1 Px2
Py
α β
1
1
arcsin x
x y
P
P Pα
= +
2
2
arcsin x
x y
P
P Pβ
= +
%10060
60⋅
°°−
=β
βD%10060
60⋅
°°−
=α
αD
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The End
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