But stare at the center of the image below long enough, and you might not be so sure there are any colors there at all:
The vanishing colors are an illusion known as Troxler’s fading, or the Troxler effect, named for Ignaz Paul Vital Troxler. In 1804, the Swiss doctor/philosopher realized that “rigidly fixating one’s gaze on some element in the visual field can cause surrounding stationary images to seem to slowly disappear or fade,” the Illusions Index noted.
In this case, your mind essentially clears out the colors and replaces them with white space.
You can read a fuller explanation, and see a demonstration using a Cheshire Cat, here.