31 May 2005

Fascinating image-processing technique

http://graphics.stanford.edu/papers/dual_photography/. A group at Stanford has developed a fascinating technique to create a picture which switches the POV of a camera with its light source. Think about that one for a sec :-)

In particular, they show an example where they have camera take the picture of the BACK of a playing card (slightly canted diagonally, but you can’t see the face). The card is illuminated by a light source off to the side. They then digitally manipulate the pixels in the camera image using their technique. This results in a second image where you can now see the FRONT of the playing card...which was not visible to the camera, but which was “visible” to the light source. Very hard to explain in words, but they have pictures and a video which are very impressive. Check it out.

There are issues with more general "real-world" applications of this ... notably, the current technology requires the light source to be a scanning light source with the scanning of a known pattern ... but I imagine that some of those obstacles may be feasible to overcome. For example, one possibly could rely on existing ambient sources of light such as ubiquitous computer monitors, or even flourescent lighting in a stretch. In which case this technology could truly be used to "see around corners" with interesting implications for intelligence gathering, military operations, and privacy.