In practice, there are usually two ways to color: additive mixing (the three primary colors: red, green, blue) and subtraction mixing (the three primary colors: red, yellow, blue).
Additive mixing refers to the mix of colors. Two or more kinds mixed together, brightness increases, the total brightness of the blend colors is equal to the sum total of mixed colored gloss, commonly known as the additive method.
In addition mixing, the three primary colors are red light (700nm), green (546.1nm), blue (435.8nm), the three are not mixed with other colors of light. Red and green light, green and blue light, red and blue light respectively mixed as intermediate colour yellow, cyan, magenta color. According to a certain proportion of red, green and blue light can be obtained white or gray light.
Additive mixing is mainly used for launching light source, such as TV screens, screens, projector screens.
Subtraction mixing mainly refers to the pigment mixing. Itself does not glow, only with the aid of light source to color, after selective absorption of different wavelengths of visible light, it presents various color pigments or dyes and other substances.
In subtraction mixing, the three primary colours are red (700nm), yellow (600nm), and blue (450nm). Using the subtraction mixing, the primary colors can call up hundreds of thousands of colors, blending the colors more, lower the brightness and purity has declined.
Application of subtractive color matching does not shine, such as ink, paint, plastics, rubber, paper, glass and other.
Under natural conditions, white light can be decomposed into red orange yellow green blue violet, light color removes the absorption of light color, and color is reflected light.

The range of visible light wavelength is from 380 to 780nm, and using light of wavelengths can be mathematically (that is adding, subtracting and dividing) converted to color matching.

When color matching, to make the color darker, there are two kinds of methods: (A) adding black, (B) adding complementary colors.
When color matching of paint with two or more colors, to avoid color darken, color hue is not complementary. Complementary color, also known as complementary colors, means two colors (equal amounts) mixed to dark grey, or containing equal amounts of red, yellow, blue, so the two colors must be complementary colors each other. Any at the end of each diameter of the color wheel opposite colors are called complementary colors.