On 17/09/15 17:32, Michael David Crawford wrote:
And what the man said: I myself experience seizures in which I lose consciousness for as long as three weeks. Before they were diagnosed I would experience seizures while driving my car then suddenly find myself in unfamiliar places without any clue how I got there. I don't know for sure but strongly suspect that modern computer user interfaces caused my seizure disorder as well as that of my cousin. Seizures are not otherwise found among any of our blood relatives.
But then if you don't use the whole screen, but only the area that should be in front of the camera of the superposed phone, then users shouldn't be subjected to much stroboscopic light. Having the objective so close from the light source does not allow the camera to distinguish pixels; for example, a black to white transition takes about 1/10 of the height of the camera view. But this means that you might still able to transmit about ten pixels at once, and you can multiply that by a number of color that you can detect reliably being that out of focus. Basically, I would expect 8 colors to be clearly distinguishable. Actually, probably more colors should be distinguishable, if you can filter out the interferences due to the grid of the camera vs. the grid of the screen. So assume 4 bits for the color, and 9 areas, that's 36 bit/moment, and you should be able to do 30 moment/second, for a total of 1080 bit/second. A little less for ECC, about 1 KB/s is not too bad. It's good enough to transmit a good private key, and then transfer the data thru wifi. Of course, if you move the camera out to focus on the screen, then you can transmit at a higher speed things like QR codes, but they could also be seen over the shoulder by high resolution cameras. -- __Pascal J. Bourguignon__ http://www.informatimago.com/ _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
