WTF is… Apple Face ID

Apple's new iPhone is great with faces - but how does it work?

Apple’s new iPhone X is a 5.8in slab of all-screen wonder. But without a home button, how do you get into it?

With your face, that’s how.

With just a glimpse of your ugly mug Apple’s new Face ID tech can tell whether the phone is being held by its rightful owner.

But how does it do it? And is it secure enough to stop your friends unlocking your new phone and filling your camera roll with with ridiculous selfies?

How does Face ID work?

At the top of the screen on the iPhone X, where the cut-out bit for the front-facing camera is, you’ll also find a infrared camera, a dot projector, a proximity sensor, a flood illuminator and an ambient light sensor.

They’re not there to take sci-fi selfies, they combine to scan your face every time you want to access your phone. Apple calls it a TrueDepth camera system.

Every time you pick up your phone the flood illuminator (we’d never heard of one either) detects that a face has been presented to it, which then triggers the IR camera and the dot projector. The former takes an infrared photo, while the dot projector maps 30,000 points on your face - a bit like motion capturing an actor for an animated movie or game.

The phone then compares those images to the map it holds of your face. If it’s a match, you’re in.

How do you set it up?

Face ID will be setup automatically when you unbox your new iPhone but it’s a very simple process. You just point the camera at your face and let it get a good look at you from all angles. That’s it.

Apple says you can even change your appearance and it’ll still recognise you, so even putting on a hat and glasses and growing a beard won’t fool it.

How secure is it?

According to Apple, TouchID had a 1 in 50,000 chance of accepting the wrong fingerprint, whereas with Face ID it’s 1 in 1,000,000. That is unless you have an identical twin, in which case you might want to stick to using a passcode, especially if they’re evil.

Face ID can be used to authorise Apple Pay transactions or access apps that used to require a fingerprint such as Mint and OnePassword. That means the banks are obviously convinced by it and those guys keep their money in massive vaults, so you can be fairly sure they take security seriously.

As with Touch ID, the scan of your face that it compares others to is stored on the phone itself, so Apple never has access to it. That’s important in the event of any hackers breaking into the systems at HQ in Cupertino.

Is it just for security?

No, the iPhone X also uses the TrueDepth camera to copy your facial expressions and paste them onto its new moving animojis, which you can then send via iMessages. Because there’s never been a panda emoji that quite captures that feeling that you've wasted hours of your life looking for the right emoji.

But does it really work?

We weren’t able to test out Face ID during our hands-on with the iPhone X, and it failed to work during Apple’s on-stage demo during the keynote, but face recognition isn’t a new technology and it’d be very unlike Apple to introduce something it’s not entirely confident will work more times than it doesn’t.

The flood illuminator is supposed to work in all lighting conditions and the infrared camera and dot sensor mean it won’t need your face to be well lit to function either.

Touch ID would often fail if you tried to use it with a wet or clammy digit, so removing the need for physical contact with the phone puts an end to that.

Our only concern is that holding your phone in front of your face to read a text message is far more hassle than just pressing the home button.

Check back soon to find out in our full iPhone X review.