Apple Final Cut Pro 5 - Manual (Page 1705)

354 Part V Appendixes
 Composite: The luma (Y´) and chroma (C) signals are combined into a single,
composite video signal for broadcast. The chroma signal is placed on a color
subcarrier frequency related to the main luma frequency. This method of
superimposing color information on top of the black-and-white information indicates
that this format originated in the early days of color television, when black-and-white
TV compatibility was critical for widespread adoption.
Black-and-white televisions are unaware of the color subcarrier, and so only the luma
(Y´) channel is shown. Color televisions reverse the composite process, recreating the
Y´C
B
C
R
component signal and then the RGB signal for display. Because the chroma
and luma channels are combined, they do not separate perfectly, causing artifacts in
the resulting image.
Aspect Ratio of the Video Frame
The ratio of horizontal to vertical dimensions of a film or video frame is called the
aspect ratio. Aspect ratio is independent of absolute image size or resolution.
Widescreen cinema
2.35:1
Standard cinema
1.85:1
High definition
1.78:1
(16 x 9)
Standard
definition
1.33:1
(4 x 3)