Biohashing and Fusion of Palmprint and Palm Vein Biometric Data Modris Greitans, Arturs Kadikis, Rihards Fuksis Institute of Electronics and Computer Science Dzerbenes 14,

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Transcript Biohashing and Fusion of Palmprint and Palm Vein Biometric Data Modris Greitans, Arturs Kadikis, Rihards Fuksis Institute of Electronics and Computer Science Dzerbenes 14,

Slide 1

Biohashing and Fusion of Palmprint
and Palm Vein Biometric Data
Modris Greitans, Arturs Kadikis, Rihards Fuksis
Institute of Electronics and Computer Science
Dzerbenes 14, Riga, Latvia
e-mail: [email protected]

International Conference on Hand-based Biometrics
November 17-18, Hong Kong

Rihards Fuksis

International Conference on Hand-based Biometrics


Slide 2

Motivation
Multimodal Palm
Biometrics
Provides:
Easy enrolment
Unique parameters
Hard to falsify

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Slide 3

Image Acquisition (I)

White LEDs

In visible light spectrum using white LEDs
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Slide 4

Image Acquisition (II)

IR LEDs

In infrared light spectrum using IR LEDs
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Slide 5

Image processing (I)
Cross section of the ridge

Cross section of the vessels

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Slide 6

Image processing (II)
Complex 2D Matched Filtering:
• Based on the matched filtering
• Improved processing speed
• Obtains vectors: magnitude – matching rate; angle - orientation in the image

CMF ( x , y ) 
Cross section of the ridge


l

e

jK  l

G ( x , y ,  l )
Cross section of the vessels

For further information:
M.Greitans, M.Pudzs, R.Fuksis. „Object Analysis in Images Using Complex 2d Matched Filters”, Proceedings of
the IEEE Region 8 Conference EUROCON 2009. Saint–Petersburg, Russia, May, 2009., pp. 1392-1397.
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Slide 7

Image processing (III)

Feature
extraction

Filtering result

Vector set

Most significant vectors are extracted to describe the object.
The result is a data set of 64 vectors (256 bytes)

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Slide 8

Raw biometric data comparison

Vector set A

Vector set B

Vector set from the database

Acquired vector set

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Slide 9

Vector comparison
v p ( A) vq ( B )

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Magnitudes:



v p ( A)  vq ( B )

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Slide 10

Vector comparison
v p ( A) vq ( B )

Magnitudes:

Angles:

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v p ( A)  vq ( B )



cos  ( v p ( A ); v q ( B ))

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Slide 11

Vector comparison
v p ( A) vq ( B )

Magnitudes:

Angles:

Distance:

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v p ( A)  vq ( B )

cos  ( v p ( A ); v q ( B ))
 d ||2 
exp   2   exp
  
|| 


 d 2
 2
 



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Slide 12

Vector comparison
v p ( A) vq ( B )

s p ,q

Magnitudes:

v p ( A)  vq ( B )

Angles:

cos  ( v p ( A ); v q ( B ))

Distance:

 d ||2
exp   2
 
||



 d 2 
  exp   2 

  


 d ||2
 v p ( A )  v q ( B )  cos  ( v p ( A ); v q ( B ))  exp   2
 
||



 d 2 
  exp   2 

  


Dot product
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Slide 13

Vector set comparison
Similarity index of two vectors:

s p ,q

 d ||2
 v p ( A )  v q ( B )  cos  ( v p ( A ); v q ( B ))  exp   2
 
||



 d 2 
  exp   2 

  


Similarity of two vector sets:

s ( A, B ) 

s
p

p ,q

q

Similarity index is normalized so that S(A,B) is in the [0;1]

s ( A, B ) 

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s ( A, B )
s ( A, A)  s ( B , B )

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Slide 14

Security of raw biometric data usage
• It is unsecure to use raw biometric data
• Therefore encryption must be introduced

10 11 00 01 01 11 10 10 00 10
Encrypted data
Raw biometric data

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Slide 15

Biohash
du
Pixels

Vectors

dv

Vector Set

CMF

(u,v)
Palm image
Inner
product

Inner
product

Random
number
matrix

...

u1

v1

R-th vector

uR

vR

Inner
product

du1 dv1
...

Token

1st vector

...

duR dvR

Data vector consists
of 4R components

...

Thresholding
1

0
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...

1

Biocode

Biocode consists of
4R bits

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Slide 16

Biohash Advancements(I)

Filtered palm vein image

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Slide 17

Biohash Advancements(I)

Filtered palm vein image

76

27

187

49

83

163

87

44

52

85

146

83

41

57

87

51

Extracted vector magnitudes

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Slide 18

Biohash Advancements(I)

Filtered palm vein image

76

27

187

49

0

0

1

0

83

163

87

44

0

1

0

0

52

85

146

83

0

0

1

0

41

57

87

51

0

0

0

0

Extracted vector magnitudes

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Most intensive vector labeling

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Slide 19

Biohash Advancements(I)

Filtered palm vein image

76

27

187

49

0

0

1

0

83

163

87

44

0

1

0

0

52

85

146

83

0

0

1

0

41

57

87

51

0

0

0

0

Extracted vector magnitudes

Data vector

u1

v1

du1 dv1 ... uR

Most intensive vector labeling

Most intensive vector information

vR

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duR dvR + 0

0

1

0

0

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1 ... 0


Slide 20

Biohash Advancements(I)

Filtered palm vein image

76

27

187

49

0

0

1

0

83

163

87

44

0

1

0

0

52

85

146

83

0

0

1

0

41

57

87

51

0

0

0

0

Extracted vector magnitudes

Data vector

u1

v1

du1 dv1 ... uR

Most intensive vector labeling

Most intensive vector information

vR

duR dvR + 0

0

1

0

0

1 ... 0

New Data vector

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Slide 21

Biohash Advancements(II)
Person 1; Biocode No.1

1 1 0 ...

Person 1; Biocode No.2

1 0 1 ...

Person 1; Biocode No.3

1 1 0 ...

Person 1; Biocode No.4

1 1 1 ...

By looking at the values before
the thresholding in Biohash
algorithm, we can obtain the
information about the distance
from threshold value for each of
the bits in biocodes

4 3 2
Random
number
matrix

Data
vector

Dot
product

Capture this value
Calculate the distance
to the threshold
Thresholding

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Slide 22

Biohash Advancements(II)
Bit #1

Bit #2

Person 1; Biocode No.1

1

0.61

1 0.33 0 0.04

...

Person 1; Biocode No.2

1

0.47

0 0.12 1 0.15

...

Person 1; Biocode No.3

1

0.59

1 0.47 0 0.18

...

Person 1; Biocode No.4

1

0.46

1 0.39 1 0.14

...

4

2.13

3 1.19 2 0.29

...

Distance to
the threshold

Bit #1

Bit #2

Bit #3

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...

Bit #3

If the distance to the
threshold value is greater,
the resulting bit most likely
will not change between
one person’s biocodes

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Slide 23

Biohash Advancements(II)
Distance to
the threshold

Bits
Sort bits into groups
Distance to
the threshold

4

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3

2

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Slide 24

Biohash Advancements(II)
Distance to
the threshold

4

3

2
Sort bits in every group
in ascending order

Distance to
the threshold

4

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3

2

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Slide 25

Biohash Advancements(II)
Distance to
the threshold

4

3

2

What we obtain is the indexes of the most “stable” bits in descending
order. When comparing two biocodes this information is used to
calculate weights for the errors of the bits by using exp or other function

Weight function

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Slide 26

Biocode comparison

= 4 mistakes

Similarity:

Sb 

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l  Dh
l

l – length of the biocode
Dh – Hamming distance

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Slide 27

Database evaluation
• Two databases; 500 images from 50 persons
• 5 images in IR and 5 in visible light spectrum
Raw biometric data comparison results[EER]
EER [%]

Palm Veins

Palm Prints

Fused data

0.32

2.79

0.1

Biohash test results [EER]
Palm Veins

Palmprints

Fused data

Mean

14.043

12.073

6.190

StDev

1.152

1.102

0.803

Proposed Biohash test results [EER]
Palm Veins

Palmprints

Fused data

Mean

1.073

0.471

0

StDev

0.304

0.231

0

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Slide 28

Conclusions
• Complex 2D Matched Filtering approach
speeds up the feature extraction procedure.
• Biohashing with proposed advancements can
be used as a method for securing the
biometric data with similar or better precision
as raw biometric data comparison gives
• Future work: Tests on larger databases and
evaluation of other biometric encryption
methods
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International Conference on Hand-based Biometrics


Slide 29

This presentation was supported by ERAF funding under the
agreement No.2010/0309/2DP/2.1.1.2.0/10/APIA/VIA/012

Rihards Fuksis

International Conference on Hand-based Biometrics