You can make almost any color at all by overlapping red, green, and blue light and adjusting the brightness of each color of light. This amazing phenomenon is due to the way the human eye works. The three colors do not have to be red, green, and blue, although those three produce the highest number of different colors. For this reason red, green, and blue are called the additive primary colors. Color television is based on the ability of the human eye to see combinations of three colors as a variety of different colors. A close examination of the picture on most color television tubes will reveal that the picture is made up of an assemblage of tiny spots, each less rea an a millimeter across. When the screen is lit, some of the spots are some green, and some blue. At a distance the mixtures of these ors provide a complete range of colors, plus white.