If you stare for a long time at a large coloured image and then glance at a white background, you'll see the same image appear, but in its complementary colours. That's because the receptors in the eye that pick up the image's colour have become tired and surrounding receptors that haven't been used take over.
While this effect is well-known, Yuval Barkan and Hedva Spitzer from Tel-Aviv University recently demonstrated the first example of a related illusion that causes the background colour to linger in a different part of the image.
In the Coloured Dove illusion (see below), a white dove appears on a coloured background. When the background is switched to white, the dove takes on a paler version of the original surrounding colour.
The team hasn't yet figured out exactly why this happens. One theory is that the dove has actually taken on the background's complementary colour from the beginning, although we fail to perceive it until the background colour disappears.