The color wheel is a vital tool in the visualizing and selection of color schemes. It shows how all the colors of the spectrum act in relation to each other, and helps you to decide on contrasting or complementary schemes. The more advanced wheel shows how tints and shades of complementary colors can work together.

How color works
When a white light source, typically the sun, consisting of different wavelengths passes through a prism, it splits to reveal the visible spectrum. It is often portrayed as a rainbow effect. The visible part of the spectrum runs from violet through to red. Ultra-violet and infra-red, either side of the visible spectrum cannot be seen by the naked eye (e g. we cannot see radio waves or X-ray.). When the walls of a room receive this white light source, they absorb all the wavelengths except those of their own color, which they reflect. The human eye responds to these reflected wavelengths and identifies them as color. So, a wall absorbing all wavelengths except blue, which it reflects into the room, appears to the human eye as a blue wall.

The wheel
The color wheel is a circle based on the color spectrum. The primary colors, red, yellow, and blue are opposite the secondary colors, green, violet and orange. Selecting colors that are opposite each other on the wheel, such as red and green, results in optimum color contrast because you are using complementary colors. Selecting colors next to each other on the wheel, say blue and green, results in a more harmonious scheme because they blend into each other in the spectrum. Blending adjacent colors together credits a third set. The wheel is divided up into twelve segments that can be used to plan all your color combinations!

Complementary colors
Complementary colors provide optimum contrast if used together in a room. They can make uneasy companions, however, if used in their purest form. All colors can be lightened by adding white to make tints or darkened by adding black to make shades of those colors. A more complex color wheel shows not only the colors at their most intense, but also the tints and shades in a gradation. This is useful because it shows how the color contrast is increased further if one of the colors is a tint or shade.

A good example of this is provided by the use of red and green together in a room. Large expanses of these colors in their purest form cause problems for the eye, because they have a similar tonal value, meaning that they reflect similar amounts of light. If you imagine these two colors side by side in black and white for a moment, then they would appear as almost identical shades of grey - neither color would advance or recede. Consequently the eye and the brain become confused. All colors from opposite sides of the wheel have a similar effect if they are of the same tonal value. However, using a tint or a shade of one of them can solve this problem. If you look at the second color wheel you will notice how dark green will effectively partner red or a tint of red. Conversely, dark red combines well with a tint of green.
 

             

(Complementary colors in the color spectrum include red and green, orange and blue, and yellow and violet).

(Being complementary colors, red and green work better in tint and shade combinations than in pure forms. But just looking at nature should be enough to convince us how well they can harmonize: think of pink wild flowers amid a meadow or of red berries against green foliage).

(Using a darker shade with a lighter tint of its complementary color avoids the visual problems caused when similar tonal values reflect similar amounts of light).