Description:A slide projector with Wratten filters is used to illuminate various colored objects such as brilliantly colored fuzzy toy animals. The animals only show a particular color when (1) the fur actually reflects, or will not absorb the color in question, (2) the illumination contains that color of light. For example, a red teddy bear will only appear red if red light is in the spectrum of the illumination. White fur takes on whatever color illuminates it. Pure blue fur appears black (no reflected light) when illuminated by light containing no blue wavelengths. Photographs below show pairs of animals illuminated in white light then red (left and left center) and white then blue (right center and right).
This is the reason why spectral streetlights such as sodium and mercury are often disdained.