So, what is color?
Color is the result between interactions of light, objects and the mind. So, if there were no humans (or other animals) there would be no color. Color perception requires a light source (such as the sun), an object (an apple) and an observer (for this example a human).
As demonstrated by Newton, light from the sun contains all colors. When sunlight illuminates an apple most of that light is absorbed by the apple’s skin and only certain colors are reflected.
Every human with normal color vision has three detectors in their eyes that are sensitive to different colors and which send a signal to the brain in response to the amount of light of a particular color. So, a red object would cause one of the detectors to send a strong signal but the other two would send a small signal. (Different ratios of these signals help us perceive millions of colors.) However, since every human is different these detectors are slightly different and so there is a range of red that each person would assign to the apple, yet would all generally agree that it is “red”.
So the process of perceiving a red apple starts with sunlight illuminating the apple, then the apple’s skin absorbing a portion of the light and reflecting another portion, then the detectors at the back of the eye respond to incoming light and send signals to the brain where it is interpreted and assigned meaning. ("That apple is bright red and looks delicious"). Ultimately, color is perceived in our brains and our brains are also the final interpreter of color.
Regardless of whether humans were around to interpret the light signals, the apple would still absorb sunlight and reflect red light but there would not be “color” because no one would be around to interpret the signals.
A couple great websites to learn more about color:
- Color FAQ (from RIT)
- Color Curiosity Shop by Mark Fairchild