Touchless Fingerprint Biometrics

Touchless Fingerprint Recognition

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5.4.4 Simulation of the Skin Color

The finger color is estimated from a real touchless fingerprint image I

l

.First,a

Gaussian low-pass filter is applied to remove the details of the ridge pattern from I

l

,

thus obtaining an image I

f

representing only the underlying skin color and the vein

pattern.Thistaskisperformedasfollows:

I

f

= I

l

∗ G

l

, (5.48)

where G

l

is a Gaussian filter with an area of m

l

×m

l

pixels and a standard deviation

equal to the empirically estimated value σ

p

.

Then, speckle noise is added using the following equation:

I

p

= I

f

+ n

s

× I

f

, (5.49)

where n

s

represents uniformly distributed random noise with mean equal to 0 and

variance equal to v

s

. Different values of the parameter v

s

are empirically estimated

to simulate ...