What are Fingerprints? People have tiny ridges of skin on their fingers They help the fingers grip things, like the rubber thread pattern on a tire help grip the road There is no chance that the same exact pattern forming twice
What does a Fingerprint Scanner Do? It has two basic jobs It first gets an image of the person’s finger Then it needs to match the pattern of the ridges and valleys in that imagine with an the pattern of a pre- scanned images.
How do you get an Image of a Somebody’s Finger? The two most common methods are Optical Scanning Capacitance Scanning
Optical Scanning It starts when a person places their finger on a glass plate, and a CCD (Charged Coupled Device) camera takes a picture. The CCD system generates an inverted image of the finger with darker areas representing the ridges of the finger and lighter areas representing the valleys between the ridges.
Optical Scanning Cont. After it proceeds to comparing the captured fingerprint with fingerprints on file.
Capacitive Scanner It starts out like an optical scanner but instead of sensing the print using light, it uses an electrical current. A finger ridge will result in a different voltage output then a finger valley. The scanner processor will put together an overall picture of the finger print