eli5: How do tech companies do it so that face ID doesn’t recognize a picture of that person?

Question

(edit: for the purposes of this question I’ll only consider Apple’s Face ID system but thank you to everyone who addressed Android and others) 🙂

In: 242

Answer 1

There is a time lag between features on a face because since parts are closer and others, farther. If they all come back the same it won’t work as the face is now not a match to the one on file.