Facial recognition, how it works and when to use it: from cell phone unlocking to security

The Facial recognition has now become a technology used daily by many people: it is a technology capable of recognizing a person's face through a camera or an image. For a few years, in fact, it has been possible to unlock one's smartphones simply by putting your face in front of the screen. It's such a simple gesture that it seems banal to us, but it isn't at all! It's about a very sophisticated technology used in various fields, including safety in crowded places such as shopping centers or airports, where it is also used for skip the lines!
Let's see in this article how the technology behind facial recognition works and its different declinations.

  • 1How facial recognition works
    • 1.1The perception of facial changes
  • 2The advantages of facial recognition
    • 2.1The risk in the 2D case
    • 2.2Gaze detection
  • 3The other uses of the phone
  • 4Safety in crowded places
  • 5The Privacy Guarantor and the AI ​​Act

How facial recognition works

For a few years now it has been possible to unlock your phone with your face. You can set up facial recognition to unlock your phone directly from your phone's settings. What we do is educate the phone to recognize us through a video that we record with our cell phone with our smartphone moving our head, through which technology has the opportunity to understand the depths of our face from different angles.

face registration facial recognition face mapping

What the phone does through this video is to map ours precisely face through the camera, that is, fills it with virtual points (over 30,000) and calculates the distance, for example how far the center of my eye is from my nose. It's about data biometric, that is, data that contains the geometry of our face.

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facial recognition biometric data detection

But not only! The most advanced technologies – such as that of the iPhone and recently also that of the new Samsung – also detect the depth of our face by analyzing the shadows thanks to a infrared light which hits the face – called flood illuminator – and one infrared camera who can read these rays, and therefore the depth of the face.

IR depth face infrared rays

In this way a cast of our facewhich comes translated into data and saved in your phone.

Whenever we want unlock your phonethe camera captures a new castproduces other data and there compare with those of the recorded cast, to decide whether it can unlock or not.

face mapping biometric points

The perception of facial changes

What happens if the our face changes following a trauma, or more simply do we change our haircut or wrinkles appear?

If something happens extreme like breaking your nose – which can thus change shape – there is a sudden change in biometric data and the phone may struggle to recognize us, so it is advisable perform a new registration of our faceas we said previously.

However, if there is some on the face trick or it changes combing, The change And light, so the phone is able to recognize us.
For aging then, it is a change slow and gradual and here too the phone continues to identify our biometric data correctly.

aging facial recognition

But as you get older you can also change a lot! So how does facial recognition know it's always us?
Thanks to a technology called neural network, that is, a mathematical model that imitates the structure of neurons in the brain. The process is this: the network collect dataidentifies gods patterns and can foresee how the data will evolve. In this case, from the facial data collected over time it can predict, for example, the appearance of wrinkles, the growth of the beard, any gradual change in our face so as to continue to recognize us.

simple neural network face recognition
Simple neural network.

But – apart from being very comfortable – what advantages does this technology have?

The advantages of facial recognition

Short answer: One of the benefits of facial recognition is that it is a technology very safe.

In technologies a infrared, the probability that a stranger will be able to unlock our phone is 1/1,000,000, 20 times safer compared to unlocking for Fingerprint, 100 times more secure than the 4-digit codeand it's equally safe compared to 6-digit code. But while it's easy to steal our code – just spy on us or try with our date of birth – our 3D face is much harder to imitate!

face ID vs touch ID

What happens, though, with i twins, very similar brothers or lookalikes? Indeed probability of deception increases greatly in the case of twins or very similar brothers, especially if under the age of 13 because the facial features are not yet marked. However, it is not possible to identify a precise probability because twins and brothers can be more or less similar.

In the case of lookalike, instead, it is a perception that they are similar! There geometry of the face it's a lot different and it is completely unlikely that the biometric data coincide.

twins facial recognition

The risk in the 2D case

It must be said, however, that in 2D case – in which the depth is not detected – actually the safety And inferior. In fact, according to a study by Altroconsumo carried out on 59 different smartphone models, 1 in 4 could have been bypassed by a photo! Therefore, before activating face control you should always check which technology is installed on your phone. You can find the technical data sheets of the various models on the internet.

Gaze detection

An important fact is that the phone cannot be unlocked while we sleep because the eyes they must be open And visible. This also applies to children sunglasses: with some the technology works because the IR camera can perceive our open eye, with others it doesn't work because some lenses block the IR rays. However this function can be deactivated – for example, if I am visually impaired or have physical disabilities and need to be able to unlock my phone even without opening my eyes. It can be done, but it makes the phone unfortunately less sure.

The other uses of the phone

Some smartphones grouped into folders the people in the images. This function is possible thanks to 2D facial recognition.

Then there are thousands of app who use facial recognition to change our face, grow old… Here, very important: if written in the privacy policy – which we must accept to use the apps – the apps can collect our biometric data, and potentially give them to third parties. In Privacy information of apps or sites – even if they are long – there are parts that always need to be read: those that concern how our information is shared with third parties, or what are ours rights on ours data.

aged face app

However, the law tries to protect us in this sense, we will see it shortly. Let's first see in which other cases – outside of the smartphone – facial recognition is used. And here we are entering an action movie!

Safety in crowded places

In many states, facial recognition is used with the intent to improve the safety of citizens. In Italy we have a system called SARI: Automatic Image Recognition System. And it looks like an action movie: when a crime is committed, if there were any cameras Of video surveillance on site, the SARI compares the faces taken up with those present in the AFIS databasei.e. a State Police database that contains fingerprints and mug images of subjects already registered.

SARI is used in crowded places like shopping centers, casinos, stadiums and venues airports where it is also used to speed up queues! In fact, from this March at the airport of Dubai it's possible travel without passportregistering your biometric data at check-in.

What if you don't want to be filmed? Let's see what the law says.

The Privacy Guarantor and the AI ​​Act

The protection of our data is very important, in fact there is the Privacy Guarantor (GPDP), which is an independent authority designated precisely to protect our data. The European Parliament recently passed the Artificial Intelligence Act (AI Act) which basically states that our biometric data they cannot be acquired from the internetimages from offices or schools. But most of all there can be no LIVE surveillance. In fact, there is a version of SARI which provides for the immediate control of the faces filmed by the cameras, so as to identify dangerous subjects. This version is not in use, because it is considered illegal, unless prior authorization is obtained from the authorities or if there is an imminent risk of terrorist attacks.

For unlocking the phone, different brands have increasingly secure technologies to prevent the spread of this data. For example on the iPhone the data is protected by a system called Secure Enclave which does not pass data to any server, and has a memory separate from the rest of the operating system. So the data remains masked – actually we should say encrypted – inside our device. That is, they cannot be stolen. The same thing goes for fingerprints.