The most basic color theory concept is the color wheel. The color wheel refers to the circle, or "wheel," of six to 12 colors. The wheel consists of three primary colors: red, yellow and blue. These basic three colors mix to create every color. The primaries create the secondary colors: orange, green and purple. Mixing primaries that lie next to one another on the color wheel creates secondary colors. For example, mixing the primary yellow with the adjacent primary blue creates the secondary color green. Colors that lie next to one another are called "analogous" colors. These colors appear similar, have little contrast and create gradual gradients when mixed. The center of the color wheel is considered a "neutral" color, like gray. Mixing complementary colors, which lie opposite to each other on the color wheel, makes this neutral gray color. For example, mixing the complementary colors yellow and purple creates a brownish grey color.
The wheel is divided into cool and warm colors. Cool colors--green, blue and purple--are used for water, plants and blue skies. Warm colors--red, orange and yellow--are used for fiery sunsets and glows of light. The value of a color refers to the darkness and lightness a color. Color saturation is manipulated by mixing the color with white, black or another color. A color with high saturation means the color is very pure, such as a pure red or a slightly orange red. A color with low saturation mean the color is duller, such as complementary color mixture or a color dulled down by mixing in white.
Cool colors often fall into the background while warm colors pop into the foreground. Artists use cool colors for distant objects, such as mountains, while using warm colors for close objects, such as Earth. The value of the colors helps create depth and form by depicting highlights and shadows. Generally, colors will begin dark in the foreground and become lighter towards the background. The greatest contrast between light and dark happens in the foreground, and the background has low contrast. Saturation helps create a sense of three-dimensional space. Highly saturated colors tend to pull forward while dull low, saturated color fall backward. Saturation is also used to create coherent and balanced, and sometimes intentionally unbalanced, color relationships. A highly saturated red next to a highly saturated makes the colors vibrate, while a dull purple next to a vibrant yellow will make the yellow seem even brighter.
RBG color stands for red, blue and green, where green replaces the primary yellow. TV and computer monitors use RBG color, and you may notice this setting when taking digital photography. CMYK color stands for Cyan, a blue; magenta, a red purple; yellow and K represents black. Printers use this color combination, but it is not typically used for painting.
Color theory is not limited to aesthetics, but also includes color's perceptual qualities. Color theorists, including Goethe and Kandinsky, believed color had psychological associations. Color can convey emotions. Blue can seem cold and sad, while red can seem passionate and aggressive. Gray muted colors can signal a melancholy feeling or even a feeling void of emotion. Bright highly saturated colors can give a loud, happy or ambitious feeling.