Here's some more information relating to between Colour Difference "Component" Video (YCrCb) and RGB (aka component in professional grade equipment) video.
Snipped from: <a href="http://www.dansdata.com/video.htm" target="_blank">http://www.dansdata.com/video.htm</a>
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RGB is the same basic system used to feed all modern computer monitors, but it’s practically never used for recording, because leaving the space-hog green data in there makes RGB take up 50% more bandwidth than the less straightforward version of component video – colour difference.
In colour difference
component video, the first channel is luminance. Notated Y, the standard abbreviation for intensity, the luminance is the signal’s brightness information with no colour data. Y by itself gives a black and white picture. The other two channels are called colour difference signals – they’re notated R-Y and B-Y, and are the difference between red and the luminance and the difference between blue and the luminance, respectively. The colour difference channels can be algebraically recombined with the luminance to give a full colour picture, without having to transmit the green data that, on most video, takes up more bandwidth than the other two colours put together (on average, green is 59% of a video signal)."
The why's of colour-difference "Component" video (forgot to snip link):
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B-Y R-Y
The human visual system has much less acuity for spatial variation of colour than for brightness. Rather than conveying RGB, it is advantageous to convey luma in one channel, and colour information that has had luma removed in the two other channels. In an analog system, the two colour channels can have less bandwidth, typically one-third that of luma. In a digital system each of the two colour channels can have considerably less data rate (or data capacity) than luma.
Green dominates the luma channel: about 59% of the luma signal comprises green information. Therefore it is sensible, and advantageous for signal-to-noise reasons, to base the two colour channels on blue and 1red. The simplest way to remove luma from each of these is to subtract it to form the difference between a primary colour and luma. Hence, the basic video colour-difference pair is (B-Y), (R-Y) [pronounced "B minus Y, R minus Y"].
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Here's a circuit that converts YCrCb to RGB
<a href="http://home.att.net/~billhudson/rybyrgb.pdf" target="_blank">http://home.att.net/~billhudson/rybyrgb.pdf</a> (though not what we're generally looking for unless you want to hook up a system that has YCrCb out to an 15khz RGB monitor... note, there isn't a sync signal.)
As for the usefulness of YCrCb Component, as others have said it's a step up from Y/C (SVideo, Luma-Chroma). Although you can't display as many colours as you would with a pure RGB signal, the result is good enough for the human eye. In fact, I believe that this is how JPEG and MPEG internally stores it's data. Thus it's appearance on DVD players.
I found out most of this when I was seeing if I could leverage the YCrCb input of my TV in order to plug an MVS to it. I think there's more info on an earlier thread.
