Service manual

STP 11-25R13-SM-TG
S - 11
c. When the entire light spectrum from 400 to 700 nanometers is presented to the eye in nearly
equal proportions, white light is seen. This white light is made up of various wavelengths that represent
different colors. Passing light through a prism, as shown in Figure S-9 can show this composition.
Figure S-9. Results when White Light Passes Through a Prism
d. The light spectrum is broken up into various wavelengths, with each wavelength representing a
different color. The ability to disperse the light by a prism stems from the fact that light of shorter
wavelength travels slower through glass than does light of longer wavelengths. Six distinct colors are
visible when passing white light through a prism. Since the colors of the spectrum pass gradually from
one to the other, the theoretical number of colors becomes infinite. It has been determined that about
125 colors can be identified over the visible area.
S-9. Summary.
Human vision characteristics are important in that the eye is the instrument that judges the quality of
color reception. Human vision is a remarkable function, but it has certain deficiencies and irregularities
that limit its effectiveness. These are intensity threshold, contrast, visual angle, and time threshold.
Certain light sources must be present in order for the eye to see. These are direct and indirect lights.
Also mentioned was the fact that the eye can see wavelengths from 380 to 780 nanometers. For
television use, this has been limited to 400 to 700 nanometers.
Section IV. FUNDAMENTALS OF COLOR II
S-10. Introduction.
We have seen how light possesses various wavelengths covering the visible spectrum and how the
spectrum is divided into various colors. Even though the colors that make up white light may be equal
intensities, the human eye does not perceive each color with equal efficiency. Let us look at how color
appears to the eye.