How Finger Print work

Fingerprint systems are now widely used, both as Attendance System and as an access control system into a room, place, or into a system.

An attendance finger print scanner has two jobs, which take a picture of your fingerprint, and decide whether the flow pattern of the fingerprint images taken with the pattern of ridges that exist in the database. There are several ways to take a picture of a person's fingerprint, but one of the most widely used methods today are optical scanning.

The core of the optical scanner is a charge coupled device (CCD), the same light sensor system used in digital cameras and camcorders. CCD is simply an array of light sensitive diodes called photosites, which generate an electrical signal in response to light photons. Each photosite records a pixel, a tiny dot representing the light that hit. These pixels form a pattern of bright and dark picture of a person's fingerprint scans.

The scanning process starts when you place your finger on a glass plate and a CCD camera takes a picture. The scanner has its own light source, usually an array of light emitting diodes (LEDs) to illuminate the ridges of your finger. CCD system produces an inverted image of the finger, with darker areas representing more reflected light (the ridges of the fingerprint), and lighter areas representing less reflected light (the valleys between the ridges).

Before comparing the images taken with the newly saved data, ensure that processor CCD scanner has taken a clear picture by checking the average pixel darkness, and will reject the results of the scan if the resulting image is too dark or too bright. If the image is rejected, the scanner adjusts the exposure time, then try the scan again.

If the darkness level is adequate, the scanner system goes on to check the definition of the picture, how sharp the fingerprint scan. The processor looks at several straight lines across the horizontal and vertical. If the definition of qualified fingerprint images, a vertical line that runs will be made up of pixels the darkest and the brightest. If the resulting fingerprint image is really sharp and well tercahayai, then the processor will compare the fingerprint images in the database.