What Are Fingerprint Minutiae

Fingerprints are known to be unique to every individual. A Minutiae is defined as: the points of interest in a fingerprint, such as bifurcations (a ridge splitting into two) and ridge endings. Types of ridges:

• ridge endings - a ridge that ends abruptly
• ridge bifurcation - a single ridge that divides into two ridges
• short ridges, island or independent ridge - a ridge that commences, travels a short distance and then ends
• ridge enclosures - a single ridge that bifurcates and reunites shortly afterward to continue as a single ridge
• spur - a bifurcation with a short ridge branching off a longer ridge
• crossover or bridge - a short ridge that runs bbetween two parallel ridges

Relevant papers:
www.research.ibm.com/ecvg/pubs/aws-constructive.pdf

MSI vs TIR

This week we read up a little bit more on Multispectral images (MSI) and total internal reflection images (TIR). The way that these MSI scanners are programmed is that they integrate both the capabilities of MSI and TIR images when the user places his or her finger on the scanner. The multispectral images are processed to enhance the fingerprint minutiae. Both MSI and TIR images are then passed into the the SDK for the scanner to detect the minutiae in the fingerprint.

Similarities:

1. Light Source - provides the light for our sensor to illuminate the platen on top of which the finger rests.
2. Imaging System – creates the digital imaging array from the image pn the platen.

Differences:

• MSI - The orientation of the light source and imagers do not exceed any critical angle conditions.
• TIR – In normal TIR sensors, the light strikes a medium larger than the critical angle.
• MSI - Has multiple illumination wavelengths,
• TIR - Monochromatic illumination system.
• MSI - uses polarizers that are arranged orthogonally to highlight the light that penetrates the skin surface. Once the light penetrates the skin surface, it undergoes multiple scattering events, once the light exits the skin it makes its way to the image array

Full Research Description of this is found in the following papers:

1. Multispectral Fingerprint Biometrics

2. Fingerprint enhancement using a multispectral sensor