The Mona Lisa is a half-length portrait of a woman by the Italian artist Leonardo da Vinci, which has been
acclaimed as "the best known, the most visited, the most written about,
the most sung about, the most parodied work of art in the world.
Leonardo
da Vinci had a great scientific mind, but even he couldn't have known the real
secret behind the Mona Lisa's smile. The proper understanding of the human
visual system was still centuries away. Still, he knew that he pulled some kind
of neat trick; the painting was one of his personal favorites and he gave it to
the king of France as a gift.
The
secret behind the Mona Lisa is that the "happy" part of her smile is
actually buried in a low spatial frequency pattern. So if you're not looking
directly at her mouth, her smile looks cheerful. But when you look directly at
her smile, parts of it disappear into the background. As a result, you're never
quite sure if she's smiling or not.
