Color plays an essential role in our day-to-day lives. From birth we are taught to react to colors logically or emotionally. Colors have meaning, which vary from culture to culture and continent to continent. It governs and controls traffic, triggers strong emotions, and is used to describe moods.

Light, perceived by the human eye, is the product of electromagnetic waves in a small range of wavelengths. Different wavelengths are perceived as different colors. Color is therefore a perceptual phenomenon, which depends on the observer and the conditions in which the color is observed (our eye-brain is very accommodating in adjusting for varying environmental conditions).

Three things are required for the presence of color:

1. an object,
2. a light source (illuminant), and
3. an observer.

 

1.1 The Illuminant

Color has been successfully used for object tracking and recognition. However, the color of an object changes if the illuminant's color changes.

To see colors, energy in the form of light is required. Color sensation is produced by physical stimuli associated with the various wavelengths in the visible portion of the electromagnetic spectrum. To understand color better, we must recognize the origin of light. Light comes from a wide variety of sources and consists of electromagnetic radiation, a form of energy that spreads in a wave motion.