Electronic Color

This page is to familiarize you with some of the characteristics of electronic color, and its relationship to pigment-based color. When talking about this relationship, it is important to first distinguish the different ways that each type of color is produced.

Electronic color is displayed on television and computer screens through the use of a cathode-ray tube (CRT). A CRT works by moving back and forth behind the screen to illuminate or activate the phosphor dots on the inside of the glass tube. Color monitors use three different types of phosphors that appear red, green, and blue when activated. These phosphors are placed close together, and when combined in differing intensities can produce many different colors. The primaries of electronic color are therefore red, green, and blue, and other colors can be made by combining different intensities of these three colors. The intensity of each color is measured on a scale from 0 to 255, and a color is specified by telling the computer the RGB values. For instance, yellow is specified by telling the computer to add 255 red, 255 green, and 0 blue.

Pigment-based color is created when different pigments absorb different wavelengths of light, and reflect or transmitt others. Pigments manipulate the wavelengths of light that our eyes receive, and the color that can be produced depends solely on the characteristics of that particular pigment. For instance, as you might have observed already in your studies, it is usually very hard to achieve the same vibrant green or orange pigment by mixing different amounts of yellow, red, or blue pigments.

These inherent differences in how each kind of color is produced also create different behaviors when each type is mixed. Electronic color is inherently additive, and pigment-based color is inherently subtractive.

A display screen starts out black; light is added to the screen in differing amounts to create color. The more light from the red, green, and blue phosphors that is added, the brighter and lighter the screen becomes. Therefore, when you have 0% intensity of red, green, and blue the screen is black and when you have 100% intensity of the red, green, and blue phosphors, the screen is white.

When you use pigments, in painting for example, you add differing amounts of paint to create color. However, the more pigment you add when mixing, the darker your color usually becomes. The absence of any pigment is white light, and the more pigments you add, the more wavelengths of light are absorbed or subtracted. Therefore, when you have 0% pigment your palette is white, when you have 100% pigment (or you have mixed together pigments that absorb every wavelength of visible light) you have black.

One of the advantages of using a computer to explore these differences is that, although computer screens are innately additive, a computer can be programmed to behave in many ways. A computer can be used to simulate any kind of color, and later on we will take advantage of this quality in order to explore additive and subtractive mixing further.

Introduction Color Models