You remember those Magic Eye pictures, the ones that looked like fields of meaningless static until you sort of crossed your eyes, and then you’d see a picture of a sailboat? According to a new analysis, Leonardo da Vinci’s “La Gioconda” — aka the Mona Lisa, possibly the world’s most famous painting — might work kind of the same way. It may be half of the oldest 3D image ever made.
The canonical Mona Lisa hangs in the Louvre in Paris. But there’s another version in the Prado in Madrid, and this knockoff Mona Lisa is a lot like the original but with a subtle shift in perspective, as if you’re looking at the same woman from a very slightly different angle. Two German researchers, Claus-Christian Carbon of the University of Bamberg and Vera Hesslinger of the University of Mainz, found that the difference between perspectives is 2.7 inches — very close to the average interocular distance, the distance between a person’s left eye and her right.
Carbon and Hesslinger's analysis.
Your brain can interpret things as 3D, including determining how far away they are, because this interocular distance means your two eyes see very slightly different views. So looking at two flat images taken from slightly different perspectives, one with your left eye and one with your right, gives the illusion of a three-dimensional object. That’s how View-Masters work, for instance. And it might be how the Mona Lisa was intended to work, too.
Or it might be that the Spanish Mona Lisa was not painted by da Vinci at all, but by someone sitting next to him. But hey, it COULD also be true that da Vinci’s “Last Supper” isn’t secretly the key to an ornate conspiracy. Do you really want to live in that world?