Introduction

Color is a phenomenon that relates to the physics of light, chemistry of matter, geometric properties of objects, as well as to human visual perception and cognition. We may call sunlight yellow, and in this case we refer to a property of light. A car may be painted red, in which case the color red is an attribute of the car. When light enters the eye, a complex chain of events leads to the sensation of color, a perceived quantity. Finally, color may be remembered, associated with events, and reasoned about. These are cognitive aspects of color. Color means different things under different circumstances [814].