Figure 1-14.
Interleaving of color with luminance signals
a. The monochrome signal (luminance or black and white), portion of the total
color signal is equivalent in all respects to the present monochrome signals. It
is formed by combining the red, blue and green signals from their respective color
camera pickup tubes in these proportions:
Y (luminance) = Q.59G + Q.30R + Q.11B
Where:
Y
=
a mathematical symbol representing the luminance signal
G
=
green signal
R
=
red signal
B
=
blue signal
(1) This particular proportion was chosen because it closely follows the color
sensitivity of the human eye. That is, if you take equal amounts of red, blue, and
green light and superimpose the rays from these lights on a screen, you will see
white. However, if you then look at each light separately, the green will appear
twice as bright as the red, and from 6 to 10 times as bright as the blue. This is
because the eye is more sensitive to green than to red and more sensitive to red
than to blue.
(2) Thus, the luminance signal is composed of 59 percent green signal (that
is, 59 percent of the output of the green camera pickup tube), 30 percent red, and
11 percent blue, and contains frequencies from 0 to 4.2 MHz.
15
Previous Page
