Afterimages are can happen when you have been staring at one place for a long time. When you look at an object, the light that falls on your retina alters the chemistry balance of your eye. This imprints an image on your retina. When you look away you see it’s afterimage. The afterimage is is opposite shades. The rainbow at the top is in inverted colors so that when you stare at it for awhile and look away onto a white surface, it is the correct colors for a second.
DiSpezio, Michael A. Optical Illusion Magic: Visual Tricks & Amusements. New York: Sterling Pub., 1999. Print.
"Afterimages." Mighty Optical Illusions RSS. N.p., n.d. Web. 17 Mar. 2015.