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114 Appendix
Frame:
One frame (two fields) of video contains the full vertical interlaced
information content of the picture. For NTSC this consists of 525
lines and PAL a frame is consisted of 625 lines.
Gamma:
Cathode ray tubes (CRTs) do not have a linear relationship
between brightness and the input voltage applied. To compensate
for this non-linearity, a pre distortion or gamma correction is
applied, generally at the camera source. A value of gamma equal
to 2.2 is typical, but can vary for different CRT phosphors.
Hue:
Attribution of visual sensation according to which area appears to
be similar to one, or proportions of two, of the perceived colors
red, yellow, green, and blue.
NTSC:
Color TV standard developed in the U.S. in 1953 by National Tele-
vision System Committee. NTSC is used in United States, Can-
ada, Japan, in most of the American continent countries and in
various Asian countries. The rest of the world uses either some
variety of PAL or SECAM standards.
NTSC runs on 525 lines/frame and it's vertical frequency is 60Hz.
NTSC's framerate is 29, 97 frames/sec.
PAL:
PAL (Phase Alternating Line) TV standard was introduced in the
early 1960's in Europe. It has better resolution than in NTSC, hav-
ing 625 lines/frame, but the frame rate is slightly lower - 25 frames/
sec. PAL is used in most of the western European countries
(except France, where SECAM is used instead), Australia, various
countries in Africa and in South America and in some Asian coun-
tries. There are various versions of PAL, the most commonly used
method is PAL B/G, but others include PAL I (used in the UK and in