The new iPhone X puts face recognition front and centre. Why? Because it is the quickest and easiest way to unlock your phone. Before you’ve even thought about placing your finger on the scanner or entering a PIN, the camera will have already processed your face, checked it’s you, and granted access.
Despite its handiness, however, the technology is far from proven. Apple keeps its algorithms under lock and key, meaning we don’t know for sure how well they work, but even the best in the business have woefully low reliability. “I wouldn’t recommend anyone trust an iPhone’s face verification,” says Stefanos Zafeiriou at Imperial College London.
And Apple isn’t the only one using software to recognise faces. Everyone from border control to high-street shops to police forces is trying to get in on the action. How much can we actually trust the technology? And do we want to live in a society where your face is always being tracked?
The best current face-recognition algorithms use a form of artificial intelligence called deep learning. Companies trawl the web to gather billions of images and use them to train an algorithm inspired by neurons in the brain, called a deep neural network. Slowly, the algorithm learns to extract features from an image that are relevant to your identity, like the position of your nose or the gap between your eyes. The more images it sees, the better it becomes.
When your face appears in front of a camera, this network kicks into action. The iPhone X also has another trick: a 3D camera that means if your head is tilted away from the screen, the algorithm can work out what it would look like if you were facing straight at it. Then if enough features match, bingo! You are successfully verified and your phone is unlocked. If not, access is denied.
“The chance that a random person…