That's why I suggested using a couple of light sources - you could take an image that's lower resolution than 1 pixel per bit and still resolve the image data to the DVD data based on the color. Eg 10 would be a different color to 01.

It's not even remotely practical but I thought it was an interesting idea. Judging by the way the votes are yoyo'ing up and down, about half of HN readers agree. :)