This text has been extracted from an article of John McGowan, you will find the complete article in this page from NASA and his face here too!
Composite video signals are analog signals that combine luminance and chrominance (color) information in a single analog signal that can be transmitted over a single wire or stored in a single track on an analog magnetic tape. The NTSC video signals used by commercial television sets in the United States and Japan are an example of composite signals. Composite video is particularly prone to errors in reproducing exact colors due to the overlap of the color and luminance signals. Video professionals jokingly refer to NTSC as Never The Same Color.
S-Video video signals separate the luminance and chrominance information into two separate analog signals that can be transmitted over two separate wires or stored in two separate tracks on an analog tape. S-Video is generally superior to composite video in reproducing colors correctly. The S-VHS and Hi8 video tape standards use S-Video. Ordinary VHS video tape uses composite NTSC signals. Thus, in general, using an S-VHS or Hi8 video camera with S-Video output to provide the analog video signal to the S-Video input of a PC video capture card will provide better video quality.
A third type of video signal is component video. In component video, the luminance (Y) and two color difference signals (U and V or I and Q) are separated into three separate analog signals that can be transmitted over three separate wires or stored in three separate tracks on an analog tape, or digitized separately. Component video is used in professional video production and provides the best quality and the most accurate reproduction of colors. The professional Betacam SP video cameras use component video. The current generation of widely used PC video capture cards do not provide component video inputs.
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Version of the document: 1.0EN
Created: January 29 - 2001
Updated: January 29 - 2001