It is a useful fact that the huge variety of colors that can be perceived by humans can all be produced simply by adding together appropriate amounts of red, blue and green colors. These colors are known as the primary colors. Thus in most image processing applications, colors are represented by specifying separate intensity values for red, green and blue components. This representation is commonly referred to as RGB.
The primary color phenomenon results from the fact that humans have three different sorts of color receptors in their retinas which are each most sensitive to different visible light wavelengths.
The primary colors used in painting (red, yellow and blue) are different. When paints are mixed, the `addition' of a new color paint actually subtracts wavelengths from the reflected visible light.
©2003 R. Fisher, S. Perkins,
A. Walker and E. Wolfart.