Service manual

STP 11-25R13-SM-TG
S - 13
S-13. Color Information and Facts.
Any given color, within limitations, can be reproduced or matched by mixing three primary colors.
This applies to large areas of color only.
a. 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 that, as the color area is reduced in size, it becomes
more difficult to differentiate between hues.
b. 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. This is relevant to our limits of vision as mentioned earlier. As
an example, a large area of blue can be readily 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.
S-14. Color Mixture.
In color television, the additive process of color mixing is used; colored lights are used 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 the additive colors. A cathode ray tube (CRT) contains
self-luminance properties, so logically the additive process would be used in color television.
a. Use of Primary Colors
. The three primaries for the additive process of color mixing are red,
green, and blue.
(1) Two requirements for the primary colors are that each primary must be different and that the
combination of any two primaries must not be able to, produce the third. Red, green, and blue were
chosen for the additive primaries because they fulfilled these requirements and because it was
determined that the greatest number of colors could be matched by the combination of these three colors.
(2) Figure S-11 shows the three additive primaries combined in a definite proportion. White has
been produced through the addition of all three primaries. Red and green combine to make yellow. The
combination of red and blue produces magenta (bluish-red), while green and blue combine to make cyan
(greenish-blue).
Figure S-11. Additive Primaries. Figure S-12. Phosphorous Dots
b. Use of Secondary Colors
. Cyan, magenta, and yellow are the secondary colors that are the
complements of red, green, and blue, respectively.