The color system is similar to black and white but is more complex.

Color Systems

Color versus Black and White

You've been shown how a visual image is created on a CCD, converted to an analog video signal, and transferred to a CRT for display. Black and white video systems operate this way. A black and white camera, if one were made today, would have one CCD and only black and white information; that is, luminance would be created and conveyed to the CRT. Color video is based on these same basic principles but is a little more complex.

Additive and Subtractive Colors

Instead of having just one CCD, high-quality color cameras have three CCDs, one for each of the primary colors: red, green, and blue. Those of you who have had art classes might say, “Now wait a minute, the primary colors are red, blue, and yellow.” Well, you're right, if you're dealing with subtractive colors. Subtractive colors are what you deal with if you're mixing paints; subtractive colors reflect light off themselves. In painting, you start with a white canvas and add colors. To get to white you have to subtract the colors until you get to the white canvas. Thus you have subtractive colors. In video, we're dealing with additive colors. Unlike subtractive colors, which depend on substances that interact with white light, additive colors depend on the color of the light itself. In this case the absence of colors gives you black. If you add all of the primary colors together, you get white. These are additive colors. With additive colors, the primaries are red, green, and blue.

Complementary Colors

You can see by the figure at the right that by mixing what appears to be equal parts of any two primary additive colors you will get one of the complementary colors. That is, equal parts of red and green will produce yellow, red and blue will produce magenta, and blue and green will produce cyan. When all three primary colors are mixed together, we have white light. By changing the proportions of the mix, brightness (intensity), and saturation of the colors, an infinite number of colors in the visible spectrum can be produced.

1.  TV colors.

2.  Color TV camera.