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Fingerprint matching from
minutiae texture maps
Contents
 The Original Approach--Fingercode
 Minutiae, Tessellation, Gabor Filter, Fingercode

 First Improvement
 Minutiae as reference points, local orientation

 Second Improvement
 Section weight, variations

 Performance and Evaluation
Background
 Fingerprint matching
 Widely used
 Give an yes-or-no answer
 fast and convenient

 Shortage for previous approaches
 Be of variable length

 Minutiae
 Ridge Endings
 Bifurcations
Fingercode
 a 640-byte feature vector
 The matching process
 calculate the Euclidean distance between the
sensored fingercode and the template fingercode
Fingercode1
 Reference Frame Determination
 reference point: Maximum curvature
 reference axis: local symmetry of ref point
Fingercode2
 Tessellation
 A plate of 120 pixels is selected and divided into
80 section

 Nomalization
Fingercode3
 3. Gabor Filter
 8 directions Gabor
filters
Fingercode3

normalized

135
Fingercode4
 Feature Vector Extraction
 standard deviation in 8*80 sections
 640 bytes
Finger 1

Finger 2
Why does it work...
 Each Garbor filter contains information about
ridges and furrows both globally and locally.
 Band width is 20 pixels.
 Inter-ridge width is 10 pixels.
 So large variation means ridges and furrows along
the direction.
Why does it work...
 Detected ref point can be 12 pixels away.
 Orientation can be 20 away
 Since fingerprint is "smooth", and we use
statistical (rather than is-or-no) data.
First Adjustment
 Minutiae as reference points
 Fingercode at every minutiae
 Ref axis along the minutiae
direction

1.Avoid pre-alignment risks
2.More robust
Second Adjustmdent
 Weighting: ADD
Problem?
 Wrong detection
of ref point can
make things
disastrous
 Errors
 Location Errors
 Orientation
Errors
Error Correction
 Orientation variation

 Localization Variation
7 Pixels
1
2

3

4
Matching
 Input fingerprints Minutiae list
 Template fingerprints Minutiae list
 Compute the Distances for each pair
8 Directions

80 sectors

 Find the minimum one
Test Data Base
 Exploit databases from Fingerprint
Verifictation Competition
 FVC2000
 FVC2002

 100 distinct fingers for each base
 8 impressions for each finger
Experimental ResultsEER-curve
 DB1 FVC2000
 d
 varied the minutiae orientations
 Compute FRR
Experimental ResultsEERs
 DB1 FVC2000
 EERs estimated for different orientation
variations

 ERR < 6%
Experimental Results
Experimental Results
 Matching performance
 Location errors: [-7,+7]
 Orientation variations:

 FVC2002
Experimental Results
 Rank according to EER
 FVC2002
 compared with other TOP 31 participants
Experimental Results
 Ref Points selection compared to fingerCode
DB1-a

 Reasons
 Noise
 The ref point is close to border
 Scars near the ref points(DB3-a)

DB2-a DB3-a DB4-a
Cons and Pros
 Pros
 Avoid pre-alignment risk
 Able to get correct result from poor picture.

 Cons
 Computaional expensiveness
Assume 30 minutiae every
picture, we have to compute
30*30=900 pairs.
END

Thank you!

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