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Unformatted text preview: nd computer monitors. Note that as compared to a computer monitor,
a TV monitor costs less but flickers often due to the lower refresh rate.
Types of Video Signals
We saw in Figure 19.2 that a pixel is composed of RGB components. Human
vision is more sensitive to variation in the luminance (brightness) than in the
chrominance (color difference). To take advantage of such deficiencies in the
human eye, light can be separated into luminance and chrominance components
instead of the RGB components.
For example, the YUV model separates
luminance from chrominance via the following linear transformation from the
RGB system Y = 0.30R + 0.59G + 0.11B
U = 0.62R-0.52G-0.10B
V = -0.15R-0.29G + 0.44B
Where Y is the luminance component and (U, V) are the chrominance
Based on these concepts of light representation, there are following two types of
video signals (for both analog and digital videos) for storage and transmission:
1. Composite video signals. A composite video signal combines the luminance
Y and chrominance C into a single stream to be stored and transmitted. Examples
of analog videos using composite video signals include broadcast TV signals and
VHS. Examples of digital videos using composite video signals include the D-2
and D-3 formats.
2. Component video signals. A component video signal separates the video into
luminance Y and chrominance C streams. Component video signals are again of
two types - the Y/C component and the RGB component.
The Y/C component
uses two separate channels to transport Y and C information, whereas the RGB
component uses three channels to carry R, G, and B colors. Examples of analog
videos using component video signals include Hi8 (it is of Y/C component type)
and Beta SP (it is of RGB component type). Examples of digital videos using
component video signals include the D-l, D-4, and D-5 formats.
Out of the two, component video signals have better quality than composite video
Broadcast Television Standards
The three main TV broadcasting standards are NTSC, PAL and SEC AM. All
three are analog v...
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This document was uploaded on 04/07/2014.
- Spring '14