A while back our great friend [Ch00f] developed a QR code clock, unreadable to both humans as well as computers. A human couldn’t checked out the clock since of the digital nature of a QR code, as well as since the clock utilized persistence of vision in driving the LEDs, a digital camera can’t catch all the pixels in the QR code at the exact same time. It’s a extremely useless however impressive art piece. Now, [Ch00f] is turning that develop on its head. He produced a rudimentary screen that is invisible to the human eye, however quickly detected with a digital camera.
This develop exploits a fundamental residential property of CMOS digital cameras – the rolling shutter. since it takes time to get pixels off a contemporary digital picture sensor, each photo is actual a composite of many different strips, each taken somewhat out of sequence. You can see this for yourself by taking a photo of something turning extremely quick with your camera phone; a photo of an airplane propeller will make the blades appear curved, or look like [Dr. Seuss] has an aeronautical engineering degree.
To produce his display, [Ch00f] discovered a few low-cost fiber optic lights. By aligning a few of these into columns as well as illumination them up in a precise sequence, he can exploit the rolling shutter as well as make an picture appear. To the human eye, it appears like a solid wall of illuminated fiber optics.
As for exactly how practical this develop is, [Ch00f] states not much. For cell phone cameras, you’d requirement to have a very, extremely short exposure time for this to work. The only method to do that is to make this screen unbelievably bright, or just put it out in the sun. We can’t see that being practical for any type of prospective utilize case, however we’d be more than happy to see a large-scale attempt at showing pictures with this technique.