Jain, 2004
Fingerprint EnhancementFingerprint Enhancement
* To address the problem of poor quality fingerprints
Noisy image Enhanced image
 Jain, 2004
Motivation for Fingerprint
Enhancement
Minutia extracted from a good quality input image
Minutia extracted from a poor quality input image
 Jain, 2004
False MinutiaeFalse Minutiae
Quality Index = 0.04
False Minutiae=27
Quality Index = 0.53
False Minutiae=7
Quality Index = 0.96
False Minutiae=0
 Jain, 2004
Difficulty in Orientation Field
Estimation
 Jain, 2004
Fingerprint Regions
Recoverable
corrupted region
Unrecoverable
corrupted region
Well defined region
 Jain, 2004
Fingerprint Enhancement
Algorithm
* A bank of even-symmetric Gabor filters is applied
to the fingerprint image
* A ridge extraction algorithm is applied to each of
the filtered images and the corresponding ridge
map is obtained
* A voting algorithm is used to generate a coarselevel
ridge map and the unrecoverable region
masks
* Orientation field estimation is applied to the
coarse-level ridge map and from the computed
orientation field enhanced images are obtained
 Jain, 2004
Fingerprint Enhancement
Algorithm
* Gabor filters are both frequency and orientation
selective
* A Gabor filter with the correct local orientation
and local frequency can remove noise while
preserving the true ridges
* The algorithm is computationally intensive and
therefore applied only to the template image
* A fast enhancement algorithm is applied to the
input images during live verification
 Jain, 2004
Enhancement Algorithm
 Jain, 2004
Fingerprint EnhancementFingerprint Enhancement
A set of 8 Gabor filters
with different
orientations is used
Ridge
Voting
 Jain, 2004
Fingerprint as Oriented TextureFingerprint as Oriented Texture
(c) Fourier spectrum of (a)(a) Ridges in local region (b) Ridge directions in (a)
The ridge pattern in a fingerprint may be viewed as an oriented
texture pattern having a fixed dominant spatial frequency and
orientation in a local neighborhood. The frequency is due to the
inter-ridge spacing present in the fingerprint and the
orientation is due to the ridge flow pattern
 Jain, 2004
Even-symmetric Gabor FiltersEven-symmetric Gabor Filters
0o orientation filter 45o orientation filter
 Jain, 2004
Results of Enhancement
Input image Coarse ridge map Unrecoverable region mask
Estimated orientation field Enhanced image Extracted minutiae
 Jain, 2004
Fingerprint EnhancementFingerprint Enhancement
Minutiae extraction before enhancement
Minutiae extraction after enhancement
 Jain, 2004
Fast Enhancement Algorithm
 Jain, 2004
Results of Fast Enhancement
Algorithm
 Jain, 2004
Performance with EnhancementPerformance with Enhancement
Quantitative evaluation of enhancement module