Fingerprint Recognition| Matching & Verification techniques

Finger prints are most reliable source of personal identity.

No two finger prints were found to be identical among millions of comparisons.

It is estimated that the chance of these finger prints being identical is 1: 64 billion population.

Hence there is absolutely no chance of identical finger prints as human population is still only around 7 billions.

Finger print recognition has been raising day by day in official transactions, employment, criminal identification etc.

Even fingerprint passwords for computers and fingerprint scanner at ATM’s for money transaction and fingerprint verification for emigration and embassy purposes is about to be widely used.

This is possible as the process of finger print recognition has become very easier and faster due to development of finger print scanner as an important  biometric system.

The finger prints consists of

1. Whole impression of finger ventral surface.

2. The ridges in the ventral surface of finger.

3. Bifurcations in ridges.

4. Horizontal cuts or breaks over the ridges.

5. The minutiae points.

Finger prints are identified by.

♠ Just seeing the impression with naked eye using parameters like

a) Shape of finger print,

b) Which finger the print belongs to i.e index or thumb etc.

c) Length of the print.

d) Width of the print.

e) The pattern of ridge formation i.e.  whorl, arch or loop type on the finger.

For details see ridge patterns in fingerprints 

These above parameters easily help compare and recognize most finger prints. But for additional assurance and accuracy we also rely on comparing the ridges and minutia points on the finger.

Fingerprint security system works by emphasis on the ridges and minutiae.

Ridges: As you can see in the image above, there are many continuous and curvy lines called ridges. These ridges are mostly never same in any two fingers of the population. These ridges travel all over the fingerprint and even may bifurcate or have diversions or sudden breaks.

Minutiae: These are small spots or gaps near bifurcation of  the ridges. These are many and randomly distributed at various places on the fingerprint.

Finger print Ridge verification:

This is done by comparing the ridges in terms of the shape of whorls at the centre of finger, by matching the tangles in ridges or by the length of the ridges etc.

Ridge verification is done in terms of the comparing curve pattern, the length of ridge per defined millimeter or centimeter etc.

Fingerprint minutiae verification:

Minutiae or small bifurcation or gaps in between ridges make fingerprint even more distinct. This makes forgery even tougher on matching two fingerprints. Because the minutiae points in a fingerprint are distributed in such a way that in the visual circle made on the fingerprint, the minutiae are distributed at different radius and position in the circle. Even the number of minutiae vary for two finger prints on verification.

Other contributing factors to personal identity of finger print are.

  1. The cuts or lines on the finger.
  2. The shape of the finger.
  3. The pressure applied during finger print impression etc.

Forgery detection:

The differences in the whorls of ridges on finger.

The finger shape like length, width.

The cuts and cross lines over the finger ridges.

The ridge patterns i.e. their style, curves, and their length.

Minutiae points number and their position on the finger print.

The actual finger i.e. is it thumbs or index finger etc.

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