Mixing green and purple paint or dye produces a dark greenish-brown color. Combining two or more colors to create a different color is called color mixing.
There are two different types of color mixing: subtractive and additive. Each of these methods has a different set of primary colors.
The three subtractive primary colors, for mixing colorants such as paint, dye and ink, are yellow, magenta and cyan. The combination of these three colors results in black.
The three additive primary colors, for mixing light or illumination, are red, green and blue. Combining these colors produces the color white. Mixing red and blue creates magenta, red and green produce yellow, and blue and green combine to make cyan.