The color magenta, which is a primary color according to Goethe's theory of color subtraction, is produced when blue and red are combined. This theory works on the principle that the components of white light can be subtracted by the secondary colors to create other colors. However, black color is produced when the secondary colors subtract all the components of white light.
Newton's theory of color is based on the principle of color addition, unlike Goethe's theory, which is based on the principle of color subtraction. Newton's theory led to the conclusion that blue, red and green colors are the primary colors, and are known as the additive primary colors while Goethe's theory led to the conclusion that cyan, yellow and magenta colors are the primary colors that are known as subtractive primary colors.
The application of these two theories of color is very common. In media production the sources of color that are used by the color print are based on the principle of color subtraction as the ambient light illuminates the paper. On the other hand, color sources that have an independent illumination, such as a computer monitor, are based on the principle of color addition.