You can harden against it using stereo cameras (3D) and different type of cameras, e.g. IR, verify with for example LIDAR, since some new premium smartphones are getting it already, this will tell you if you’re looking at a projection. Also see what smartphones are already doing for face authentication tech. Now, that said, you can never defend against it 100%. The most obvious is you can always fallback to just hiring actors/makeup/etc. If someone is determined enough (major actor) they can probably still produce fake pictures and authenticate them, but it would be significantly harder, and basically impossible for majority of people.