The three primary colors are red, blue, and yellow; however for the light generated “additive” model red, blue, and green are used. Secondary colors are created by mixing primary colors, e.g. mixing the primary colors red and blue create the secondary color purple. Similarly, tertiary colors are mixes of secondary colors. Additive models are light generated, such as screens, whereas subtractive color models are made of pigment. Color greatly affects human perception in many ways, including appetite and mood. The surrounding colors of a given color changes its intensity, as we saw with the checkerboard shadow illusion.
