With the release of the new iPhone, apple paved way for its competitors to develop more on the facial recognition aspects of biometric security. The system is fool proof they say, it could work even without proper lighting conditions in the room (tho the Chinese say iPhones are racist as some of them got bad experiences with their colleagues and siblings opening their personal iPhones easily, without a twist). Anyways, these systems which are revolutionizing for quite a period now has caught our attention. Some of the inclined people might even get too curious and wonder how the basic biometric systems work. Like how do they understand a person’s individual physical characteristics and recognize the person correctly? This indeed is a vast subject, but today we will concentrate on the technicality of a basic fingerprint recognition system. And thus we begin to understand… Minutiae.

Iphone Fingerprint Sensor

Why do we have fingerprints?

I doubt that you have thought about it prior reading this. Our mammalian evolution chain has granted us with a lot of useful features like opposable thumbs and so on. Everything in our body serves a purpose. Have you ever seen someone when pulling something with a rope, tying the rope around 3-4 times around the object? Why is it needed?

As you might have guessed, tying it more than once increases the frictional grip of the rope above the object. And thus the rope grabs more tightly on the object enabling us to pull it. The fingerprints in out hands serves a similar purpose. The ridges at the end of out fingers (frictional ridges) increase the force of friction between our fingers and the object we hold. The significance of this fingerprint feature which we obtain even before we are born out to this world, is in the fact that it’s unique to every living person in this world. Brilliant minds exploited this aspect to cash it out into a unique security feature that enabled our thumbs to unlock our phones.

How does it work?

Look closely into your fingers and you would see some of the lines terminating and some of the lines splitting into two. A computer looks for these patterns, measures the angles and distances between these features and stores these information, pointed out by a unique numeric code. When a person request a computer to validate his fingerprint, the information he currently provided is matched with the other records stored in the database and if a match is found, his fingerprint will be accepted. These patterns which a computer checks for in your finger are called as Minutiae.


The Mind of the Scanner

Let’s see how a fingerprint scanner works.

  1. Bright lights (commonly LEDs) are placed right below the glass screen surface in which we touch to register our fingerprints.
  2. The light which reflects back from the ridges in our hands are captured by an image sensor (CCD/CMOS). The quality of the image captured by the sensor depends hugely upon the cleanliness of our fingers.
  3. If the fingerprint is kept pressed for a longer time, a brighter image is captured. If the image is not usable, the checking algorithm gives a sound and LED feedback to the user.
  4. If the image is acceptable, another algorithm counts the minutiae details and saves the information into the memory.
  5. The information is stored to be used later, when the user requests access.



Biometrics is a vast field with new technologies popping up every minute. The only way to be even remotely significant in this area is to be updated constantly about new technologies. For that to happen, we need to learn how the present systems work.

Kudos to technology.

Thanks for reading.