subliminal color images

[Kragen Javier Sitaker]

It would be cool to print out a black-and-white image on, say, a laser
printer, which contained an unobtrusive embedded "watermark" or
"barcode" that contained chroma information for the image --- rather
like what the Apple II did to get NTSC color just by producing a
pattern of 1's and 0's.

Then you could point, say, a cellphone camera at the image, and push a
button, and see the image in color.