Color Systems - Primary Colors

There are actually two color systems: one which deals with emitted light and one which deals with reflected light. A luminous source produces light; illuminance is reflected light. A computer monitor is a self-luminous source because it emits light. Your keyboard, mouse, and desktop are reflecting light from a luminous source in your environment. They are being illuminated by a lamp, ceiling fixtures, or sunlight. If your keyboard or mouse has an LED, the LED is a luminous source because it emits light.

All of the colors of light that we perceive can be produced by combinations of the three primary colors: Red, Green, and Blue. However, how these colors mix depends on whether we are dealing with emitted luminance or reflected light. These two different color systems are referred to as: additive and subtractive, respectively.

• Additive - pertains to self-luminous light sources. Mixing equal amounts of red, green, and blue light produces "white" light. The absence light creates "black."
• Subtractive - pertains to an illuminated object that reflect lights, but does not produce its own. The color we see is the color reflected from the object; the colors we do not see are absorbed by the object. "Black" is the absorption of all colors, that is, the mixture of all colors. "White" is the reflection of all colors.

This course will primarily address additive color as it pertains to computer monitors and self-luminous displays.

Additive Color	Subtractive Color
Applies to Light Sources Computer Monitors Emitted Light	Applies to Reflected Light Printed Images Pigments & Paint