Brilliance From Siggraph: Bokeh-Based Tiny Barcodes

Bokeh” is a term used by photographers to praise the out-of-focus areas of a photograph.

Researchers at MIT have figured out how to exploit bokeh so that they can read 3mm barcodes with 2.5 micron elements at a distance of 4 meters with an off-the-shelf camera!

The “bokode” dot uses a lenslet to create lightrays which, when captured by a large aperture lens focused at infinity, reconstruct a pattern. The orientation of the bokode to the lens is highly recoverable. As a guy who just spent some time prototyping an augmented reality application and being foiled by the challenge of capturing exactly this information, I’m blown away.

More generally, I’m blown away by the transformation of “optics” into information processing. In my newfound hobby of astronomy, guys with 4″ telescopes are creating images better than observatories could produce a few decades ago.

3 thoughts on “Brilliance From Siggraph: Bokeh-Based Tiny Barcodes

  1. If I’m not mistaken, the use of a pinhole focusing device means that they’re quite sensitive to exposure; a pinhole is effective in focusing in proportion to how small it is, but is bright in inverse proportion. They do talk about using a flash with reflective material in the “bokode” for passive bokodes, which I presume means that their demo is using active bokodes, i.e. directly emitting light to make sure the pinhole isn’t lost in the overlap of other light sources in the out of focus image. I expect it’s this exposure / contrast problem which has meant the technique hasn’t been used much before.

    Still, pretty dramatic demonstration of the power of pinhole lenses.

  2. Check out the MIT site.

    Currently, the Bokode requires a light source ( the LED ) but work is in progress on holographic versions.

    There are lots of links there to technical and non-technical material, as well as suggested applications (which are pretty exciting)

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