[joshvm]

Figure 12 is wild. They take an image from overhead a scene - a box which contains a mirror (perpendicular to the camera so you can't see the surface) and some other objects. They illuminate from the side (shining into the mirror) and are able to reconstruct that view. That is an image facing the mirror whose surface the camera can't see and it correctly shows reflections.

[laughinghan]

Did you see Figure 16?? The camera is pointed at the back of a playing card (like, from a 52-card deck), and the front is faintly reflecting light onto a book, and they're able to reconstruct a shockingly clear image of the front of the card (King of Hearts, spoilers).