Among other things, Jim Henderson saw fit to write:

>> I don't see why it isn't possible.  The projector is lighting one tiny
>> segment of the card at a time, if it hits a red bit, the book is going to
>> be lit with a red hue, very easy to pick up by the camera.  Once it's
>> scanned the whole card, it would be easy to build up the picture.
> 
> That's the trick, though - the projector shown in the video, unless I'm
> terribly mistaken, is just a standard video projector (the type you might
> plug a PC into to project it on the screen) - so the projector is in fact
> lighting the entire book/card scene all at the same time.

As I understand it, the scene is lit "pixel by pixel", and the resolution
use for lighting is the resolution you get in the "dual image". If all the
scene is illuminated at once, it makes no sense talking about the projector
resolution. Besides, in the paper there is a figure for the card trick that
shows the different images seen by the camera when the light is sent to
different "pixels" of the card.

Anyway, I believe those projectors, like TVs and monitors, actually perform
a sweep over the screen, and we see it as a whole image due to... guess
what, persistence of vision ;-) (and maybe to screen persistence on TVs and
monitors). What would probably be needed is to slow down the scanning in
the projector or to use a very high speed camera.

-- 
light_source{9+9*x,1}camera{orthographic look_at(1-y)/4angle 30location
9/4-z*4}light_source{-9*z,1}union{box{.9-z.1+x clipped_by{plane{2+y-4*x
0}}}box{z-y-.1.1+z}box{-.1.1+x}box{.1z-.1}pigment{rgb<.8.2,1>}}//Jellby

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