Saturday, January 27, 2007



The word "bio" means living, and "metrics" means by measure.


Biometrics can be defined as the technique of studying the physical characteristics of a person, such as finger
prints, hand geometry, eye structure etc.


An increased need for security has prompted even every day office goers to install finger print recognition devices. The question is why? Simply because finger prints are more secure, far better than password. Unlike passwords the finger prints cannot be faked.


Your finger is the key that unlocks your car and starts the ignition. Your eyes are your bankcard to withdraw
cash. Your hand is the security software that protects your network from intrusions and fraud. Your face opens the door to your workplace.


The concept of biometric verification is simple. The system has some pre-stored data. When you approach the system your finger is scanned and matched with a record of finger prints already in database only when it finds a match access is granted.


Humans have finger prints for the exact same reason the tyres have treads. Different people have entirelydifferent sets of finger prints which enables identification. The most commonly used method of scanning is optical scanning. An optical scanner has a CCD (charge coupled devices)Similar to ones used in Digital cameras. There is an array of light sensitive diodes. When these diodes come in to contact with light, then generate electrical signal. Every signal records a pixel representing the light it came in contact with. The process begins as soon as you place finger on the scanner or sensor. It scans the finger patterns of your finger, but it does not just rush off to match if with images in database. It first checks for integrity of image in terms of contrast sharpness and sheer quality.


Retinal scanning is rather older technology used. Research on this started in 1930's. For retina to be scanned the user looks through a small hole in scanning device and focuses on a particular point for some time. During this time the low intensity light and a CCD analyze layer of blood vessels at back of eye for atching patterns. This technology is still not in the public domain, and is used in high sensitive areas.There is absolutely no known method of replicating persons retina and to use dead mans retina is no good as it gets damaged soon.


Iris scan, though related to the eye, uses a completely different method of identification. The Iris is colored
ring surrounding pupil. Over 200 points can used for comparison such as the rings. The scan is done with a
regular camera and the subject stands about a foot from lens come so it is convenient.Iris pattern is much more unique than finger print. The probability of matching two irises is 1/10 power 78.


Facial recognition is completely different from the above. Since people going through finger print, retinal, iris are aware and they take precautions. But by using a facial recognition we can pick up a face from say thousands of people in an airport, etc. We can identify a person with some distinguishable
features.The software divides the face into 80 nodes. Some of common nodes are distance between two eyes, ears, width of nose, width of mouth, width of cheek bones, pattern of chin, etc. This software has the ability to pick up a face we wanted from a crowd.The system generally needs 14-25 nodes in order to get a +ve ID.


Like a finger prints and face attributes every person has a unique speech pattern.Speech recognition is that Converts text to speech.Voice recognition is that Converts person’s voice into an audio file known as “Voice Print”. Every person has some different pitch of voice with which we can identify a person. During this process system asks to choose a phrase and asks to repeat it. The phrase should be 1 to 1.5 seconds in length.Voice recognition cannot be practiced in heavy traffic, etc.


  • Recently Microsoft Launched laptops, note books, with finger print enabled software to log in.
  • ATM’s in USA use finger print recognition, if every thing goes right, we are allowed to make transaction.
  • The TIRUPATHI DEVASTHANAMS in our country has also deployed use of finger print recognition.
  • US military uses IRIS, RETINAL scanning to combat terrorism.

-Manoranjan Reddy Mandadi