Video signals can be organized in three different ways: Component video, Composite video, and S-video.

Component Video

Higher-end video systems, such as for studios, make use of three separate video signals for the red, green, and blue image planes. This is referred to as component video. This kind of system has three wires (and connectors) connecting the camera or other devices to a TV or monitor.

Color signals are not restricted to always being RGB separations. In contrast, most computer systems use component video, with separate signals for R, G, and B signals.

For any color separation scheme, component video gives the best color reproduction, since there is no "crosstalk" between the three different channels, unlike composite video or S-video. Component video, however, requires more bandwidth and good synchronization of the three components.

Composite Video

In composite video, color ("chrominance") and intensity ("luminance") signals are mixed into a single carrier wave. Chrominance is a composite of two color components (I andQ, or U and V). This is the type of signal used by broadcast color TVs; it is downward compatible with black-and-white TV.

In NTSC TV, for example [1], [ and Q are combined into a chroma signal, and a colorsubcarrier then puts the chroma signal at the higher frequency end of the channel shared with the luminance signal. The chrominance and luminance components can be separated at the receiver end, and the two color components can be further recovered.

When connecting to TVs or VCRs, composite video uses only one wire (and hence one connector, such as a BNC connector at each end of a coaxial cable or an RCA plug at each end of an ordinary wire), and video color signals are mixed, not sent separately.

The audio signal is another addition to this one signal. Since color information is mixed and both color and intensity are wrapped into the same signal, some interference between the luminance and chrominance signals is inevitable.

S-Video

As a compromise, S-video (separated video, or super-video, e.g" in S-VHS) uses two wires:one for luminance and another for a composite chrominance signal. As a result, there is less crosstalk between the color information and the crucial gray-scale information.

The reason for placing luminance into its own part of the signal is that black-and-white information is crucial for visual perception

Therefore, color information sent can be much less accurate than intensity information. We can see only fairly large blobs of color, so it makes sense to send less color detail.