Sunlight, which is pure white light, is composed of several visible colors of light. The main colors of white light are Red, Green and Blue. The basis for these colors are the color-sensitive cone cells in the human retina.

These three light colors are the three Additive Primary Colors. When you combine additive colors, they create a lighter color.

These three primaries are the basis of the Additive Color Model, also called the RGB model. This is the model used to create color on computer displays, televisions, and video projectors, all of which use combinations of red, green, and blue phosphors.

The RGB Additive Color System

The RGB color system occurs whenever light is projected to form colors. RGB stands for RED, GREEN and BLUE, which are the Primary Colors.

The RGB (Red Blue Green) Colors form the Additive Color System. Images on a computer monitor are formed from light that is projected from multiple pixels, each pixel having one of these three Primary Colors. By combining different amounts of each of these colors, a monitor can display up to 16.7 million different colors.

This color system is called the Additive Color System because when these three colors are combined (added together) in equal amounts they form white light.

When Red and Green overlap, they form Yellow, when Red and Blue overlap they form Magenta or Purple, and when Green and Blue overlap they form Cyan or Blue-Green. Black is the absence of all light. Additive Colors get lighter when mixed.

The CMY Subtractive Color System

CMY (Cyan Magenta Yellow) form the Substractive Color System. Cyan, Magenta and Yellow are the three Subtractive Primaries. Nearly any color can be produced (in theory) with different combinations of these three colors using inks or paints. Actually, when you mix all three together in equal amounts, instead of getting black, due to impurities in the inks and paints, the result is a muddy brown, so printers use the CMYK process. (Picture by Pantone)

This system is called Subtractive because when you mix two colors, the resulting color subtracts or absorbs even more light waves from white light than the first color did. Subtractive colors get darker when mixed.

The CMYK process has the additional color of Black and is used by computer printers. In the CMYK process, by using Cyan, Magenta, Yellow and Black inks you can mix the inks and achieve nearly any color.

The Pantone Matching Color System

Pantone Inc. (www.pantone.com) is a US corporation. The company is well known for its Pantone Matching System (PMS), a proprietary color system used in a variety of industries, including the manufacture of colored paints, fabric and plastics. They are probably best know for their color system in the printing industry.

The company is most well known for it's Pantone Guides, which are a stack of small cardboard sheets, printed on one side with a series of closely related color swatches and then bound into a small flipbook. On a single page you would see a number of varying tints for a single color such as red.

The PMS system allows designers to 'color coordinate' specific colors when they design a product and these color swatches become the defining standard for the product color no matter what equipment is used to produce the product. This system has been widely adopted by graphic designers, reproduction and printing houses for many years.

Pantone recommends that PMS Color Guides be purchased annually since the inks become yellowed over time. Color variations also occur between editions based on the paper stock used.

In the next section on Color Palettes and Color Models, I'll explain the different Color Palettes that are used for GIF files and the Color Models that are used for the files of high color graphic images.