An optical illusion by Akiyoshi Kitaoka.
The spirals of magenta, green, orange and blue swirl in perfect unanimity.
But at the behest of your cranial noodles, the green and blue are really one colour. Incredible! Load the image up in photoshop or even the paint program and check out the specs.
The colours look different because our brain judge each object by comparing it to its surroundings. Look here.
The orange stripes don’t pass through the “blue” spiral and the magenta stripes don’t pass through the “green” one. The fact that the orange crosses through one spiral and not the other forces the brain to make a comparison; thereby providing the viewer with the colour green. The same can be said for the magenta spirals.