Why Won't Facial Recognition Unlock Your Phone If You’re Looking Sideways?

24 April 2019, 16:24

Man looking at phone
Picture: PA

Question: Why will facial recognition unlock your phone if you're wearing sunglasses, but won’t if you’re looking sideways?

Name: Bartik, Kew Gardens

Qualification: IT Engineer

Answer: Facial recognition uses infrared light to make a 3D scan of your face and determine whether it is really you or not. Some sunglasses block infrared light, so the phone can’t see a large part of your face and can’t tell if it is you or someone else.

Even if you buy glasses that don’t block infrared light, you have to look directly into the screen, because the phone wants to ensure your eyes are pointing directly towards it and that you are paying attention to prevent accidental unlocking. Otherwise, someone could grab your phone and put it to your face even if you aren’t looking directly at it.