Graduated Rulers

Stretch out this image by Erhard Schön …

http://en.wikipedia.org/wiki/Image:OpticalIllusion.JPG

… and you’ll see images of Charles V, Ferdinand I, Pope Paul III, and Francis I:

http://en.wikipedia.org/wiki/Image:OpticalIllusion.JPG

Big deal, you say, anyone with a computer can make a compressed image.

Well, Schön made this one 1535, as a wood carving. Beat that.