A few months ago I published some experiments I’d been doing emulating MIT’s Bokode technology at home. For those of you who don’t know Bokode is a method developed in the Camera Culture Group at the Media Lab that tucks huge amounts of readable graphic information into a space as small as a LED. This is done by using tiny printed info just behind a lens and just in front of a strong light. When you point a camera at the lens and pull out of focus the lens projects a blown up image of the microprint on your camera’s film plane.
You might have noticed the blurry blobs that show up on film when you take a picture of distant lights or pinpoint bright spots that aren’t quite in focus. This effect is called Bokeh, after the Japanese word for blurry. You can find details on how it works here, and details on how MIT used this effect and turned it into a way to create passive, unobtrusive tagging with Bokode here.