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You probably know those red eyes on photographs. This idea puts that nuisance to good use. Combine a cheap camera with an ultra short flash. The flash is so short that the human eye doesn't even register it. The image processor behind the camera looks for the red eye generated by this flash. That way
it can decide if someone is staring at the camera and trigger some action.
A typical application could be an automatic faucet where you put your hands under and it turns on. You stare at the red button on the right side until it is warm enough, or you stare at the blue button on the left until it is cold enough. Of course each button has a built in camera. The buttons should still be real buttons and offer a mechanical alternative for those idiots who wear sun glasses in the bathroom.
<Note: If you feel that there just was another idea posted about faucets your feelings are correct. Today I had a hard time getting grease off my hands at Home Depot because the water was too cold.>
Optical chopper
http://www.thorlabs...287&Product_ID=1136
If the link doesn't work go to the home page and search for "chopper". [kbecker, Oct 05 2004, last modified Oct 17 2004]
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Annotation:
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//it's hard to stare at something for a long time// We are not talking about minutes here, just enough so the camera knows its not an accidental blink. After that it would just be a few seconds until the temperature is right. |
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//Some industrial grease removers actually work better without water.// I know they do, at Home Depot they actually have that orange stuff. It works great, but they don't offer it in the restroom. |
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Oh, my. I feel a wave of photo-optical ideas coming on. |
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It seems that the flash would have to be periodic to be useful, perhaps even as fast as a strobe. But then wouldn't the pupils get small, and get rid of the red eye? |
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This seems like a new solution to a problem that has already been solved. Alan Alda demonstrated an eye tracking computer on Scientific American Frontiers some time back. I think it was involving helping a girl communicate. |
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More importantly, is it possible to make a flash of light fast enough to be unnoticable to human eyes, but strong enough to cause red eye? |
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[swami] That system works nicely but is still way too expensive. The red-eye analysis would cut out a lot of complexity. |
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[Over] The eye responds to average power (averaged over several milli sec) but you can set up your sensor to respond to peak power on a very short time and only watch during the pulse. That way you get rid of the background light too. It is one reason why researchers spend money on choppers for their ligth (link). |
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Now, with face recognition software in consumer cameras, it might be possible to control TVs & lights by looking and blinking. A once for on and twice for off type of thing. |
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I'm pretty sure there are cameras for footfall detection in advertising metrics (to see who is looking directly at your advertising) that do just this, but I think they use IR rather than visible light. |
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Use infra-red or ultraviolet light. If the eye can't see it, the pupils won't contract, and there's less need to make the pulse ridiculously short. |
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//Use infra-red or ultraviolet light// UV is very bad for the cornea. |
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