A magician reveals his visual tricks

Earlier today I posted five optical illusions by Olivier Redon, a French-American inventor. Here they are again – with demonstrations of how he created the effects.

Three of the images are inspired by the Necker cube, a two-dimensional drawing of a cube that can be understood in two ways: either with the bottom left face at the front, or the top right face at the front. Once your eyes settle on one interpretation, it is hard to see the other.