occurs at a wavelength of approximately 555 nanometers and that less response is
indicated on either side of that point. From this information, it can be seen that
the average person's eye is most sensitive to yellow-green light.
2. Qualities of color. There are three qualities which are used to describe any
one color. These are hue, saturation, and brightness.
a. Hue is a quality which is used to identify any color under consideration,
such as red, blue, or yellow.
Hue, which defines the wavelength of the color,
would be synonymous with frequency, which defines the wavelength of the radio wave.
b. Saturation is a measure of the absence of dilution by white light and can be
expressed with terms such as rich, vivid, or pure. Saturation defines the purity
of the color, and is synonymous with signal to noise ratio, which defines the
purity of the radio wave. A 100-percent saturated color contains no white light.
c. Brightness defines the amount of light energy which is contained within a
given color. It is synonymous with amplitude, which defines the amount of energy
in the radio wave. Brightness is a characteristic of both white light and color.
Hue and saturation are characteristics of color only.
The brightness level of a
color can be changed without changing the saturation. The converse is also true.
3. Any given color, within limitations, can be reproduced or matched by mixing
three primary colors. This applies to large areas of color only. Color vision for
small objects or small areas is much simpler because only two primary colors are
needed to produce any hue. This is because, as the color area is reduced in size,
it become more difficult to differentiate between hues. For small areas every hue
appears as gray. At this point a change in hue is not apparent; only a change in
brightness level can be seen.
For example, a large area of blue can be easily
distinguished from a large area of blue-green.
However, when these areas are
reduced in size, it becomes more difficult to distinguish between the colors.
4. Color mixing.
In color television, the additive process of color mixing is
used.
It uses colored lights for the production of colors.
The colors in the
additive process do not depend upon an incident light source; self-luminous
properties are characteristics of additive colors. Cathode ray tubes contain self-
luminance properties, so it is logical that the additive process would be employed
in color television.
a. The three primaries for the additive process of color mixing are red, blue,
and green.
Two requirements for the primary colors are that each primary be
different and that the combination of any two primaries do not produce the third.
Red, green, and blue were chosen for the additive primaries because
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