Colors On the Web

Color Wheel

In color theory, we often talk about the color wheel. A color wheel is really just the spectrum twisted around so that the violet and red ends are joined. The color wheel is particularly useful for showing how the colors relate to each other and how you can create new colors by mixing two or more colors.

Primary Colours

Among the colors in the color wheel, there are three colors which are referred to as the primary colors. All other colors can be created by mixing these three colors. The primary colors are, as seen in the figure to the left, red, green and blue.

Why red, Green and Blue?

This might require a bit more explanation - There really is nothing intrinsically primary about red, green and blue, rather they are just points on the color wheel. In fact, in the print industry the primary colors are considered cyan, magenta and yellow. (commonly referred to as cmyk, where k stands for black).

Additive Color System

If you look very closely at your computer screen or TV (any color source that emits the light itself) you will see that it is built up of tiny red, green and blue dots. This color system is commonly referred to as the Additive Color System. In the additative system, you get white when the three primary colours are present at 100%, as seen in the illustration to the left.

Subtractive Color System

As I said above, the primary colors in printing is considered cyan, magenta and yellow. This is also called the subtractive color system. The subtractive colour system is what comes to play when the color does not emit any light of its own, but reflects light from its surroundings. In the subtractive colour system, you get black when all colours are mixed.
Since on the web we are dealing only with colours on the screen, the additative system is the only one we need to think about.

Secondary Colors

The secondary colors are what you get when you mix any two adjacent primary colors. Red and green give yellow, red and blue give you magenta and a mix of green and blue result in a cyan color. The secondary colors are also the primary colors in the subtractive color system.

Tertiary Colors

To complete the color wheel we need to add the tertiary colors. The tertiary colors are those which lie in between the primary and secondary colors. As you can see on the color wheel, they are a further blending of adjacent colors.

The complete wheel

Adding it all together, we get the complete color wheel. The color wheel is the foundation for much of color theory, and you would do well to remember what it looks like and where the colors are in relation to each other.

Hue

Hue is somewhat synonymous to what we usually refer to as "colors". Red, green, blue, yellow, and orange are a few examples of different hues. The different hues have different wavelenghts in the spectrum.

Value

The value is a measurement of the brightness of a colour. The brighter a colour is, the higher is its value and the more light it emits. For instance, a vivid yellow is brighter than dark blue, therefore its value is higher than that of the blue. A good way to see the difference in the values of colours is to look at the corresponding greyscale version.

Tint and shade

These are terms to describe how a color varies from its original hue. If white is added, the lighter version of the color is called a tint of the color. On the other hand, if black is added the, darker version of the color is called a shade of the color.

Saturation

Saturation can also be called a color's intensity. It is a measurement of how different from pure grey the color is. Saturation is not really a matter of light and dark, but rather how pale or strong the colour is. The saturation of a color is not constant, but it varies depending on the surroundings and what light the color is seen in.