Imagine the following scenario: you have a paperback book open to a printed page, a camera, and an LCD projector that form a rough triangle. Suppose you have a playing card, with its back facing the camera. The front of the card partially faces both the projector and the book, so light from the projector will create a diffuse reflection from the card’s face on the page of the book.

Now, you might think that it’s impossible to determine the suit and value of the card from the camera’s perspective—the only information available to the camera is the light reflecting off the back of the card, and the light from the open book page. However, by controlling the structure of the light from the projector in a very fine manner (illuminating one “pixel” of the playing card’s face at a time), the entire card can be scanned in, a piece at a time!

“Seeing around corners” is perhaps an exaggeration, but this technology is just plain cool. For more technical information, check out the paper behind the discovery, Dual Photography, or jump straight to the demonstration video (torrent) or the paper in PDF format.

Grab the torrent if you’ve got the time—the end of the movie demonstrates the playing card scenario I described above. It’s fantastic.

PS. If you don’t have a BitTorrent client, head over to the official web site and download it. BitTorrent is a peer-to-peer (P2P) technology that shares the burden of downloading among everyone who wants the file. Rather than everyone attempting to snag it from a single computer, people with more pieces of the file than others share it with the group. This greatly accelerates download time, and allows many more people to download the file without overloading the server. P2P is not evil!