It selectively depolarizes the photoreceptors in your retina and then you see the "after image" when you look away from it (white depolarizes the most, so the after image creates a black color for the hair. The face has a blue tint which depolarizes the blue cones and you get a slight red tinge when you look away. Also you brain sees color and brightness by contrasting it to what's next to it; and the contrast also adds to the image.