YPbPr与YCbCr

YPbPc是逐行扫描色差接口，YCbCr是隔行扫描色差接口。

YPbPr是模拟信号，YCbCr是数字信号

在色差输入的标注方面，每个产品的写法都可能不一样。有的产品上标注“Y CB CR”表示可接受隔行色差信号，而“Y PB PR”表示逐行色差信号或者HDTV色差信号，而“Y CB/PB CR/PR”表示可自动识别隔行/逐行色差信号。你应该以产品的实际说明为准来判断设备可接受的格式，而不是“写”了什么。在专业领域了，“Y CB CR”表示数字色差信号而不是模拟色差信号。

 

Difference between RGB (VGA) and YPrPb (YUV)

RGB contains the separate informations for the red, green, and blue component as separate channels. The sync signal can be provided as sync on green RGsB, one combined sync signal RGBS, separate sync signal for horizontal and vertical RGBHV or sync on all three RsGsBs.

Each of the three channels R, G and B include the color signal and the luminance information. Viewing any of the three channels separately, a black and white image is visible, because the Y information is included in all three channels. This is a wast of bandwidth, because it is actually three times the same signal.

By using just a channel for the luminance information and two channels for the color information, bandwidth can be saved by carrying the same information.
Component video YPrPb (YUV) consists of three signals. The first is the luminance signal, which indicates brightness or black and white information that is contained in the original RGB signal. Monochrome signals contain only intensity luminance information, also called luma. It is referred to as the Y component. The apostrophe indicates that the component is gamma corrected.
The second and third signals are called ''color difference'' signals which indicate how much blue and red there is relative to luminance. The blue component is B-Y and the red component is R-Y. The color difference signals are mathematical derivatives of the RGB signal.


When color information is added to the video signal, the luma signal is left intact for compatibility with existing equipment, and two color information components are added. They are called U'' and V''.
Y''Pr''Pb'' (Y''U''V'') signals are matrixed components. The luminance Y signal is derived from the Red, Green, and Blue components by the formula 30% Red, 59% Green, and 11% Blue. The R-Y signal (Pr) is derived by subtracting this luminance signal from the Red signal. The resulting signal contains only color difference component for red.
The B-Y or Pb signal is derived by subtracting the Y signal from the blue signal to get the color component of blue. A G-Y component for green is not needed because all information is carried with the Y signal and the red and blue color component.

The color components are also called color difference signals. The U'' component is the difference between blue and luma and the V'' component is the difference between red and luma.

The reason to use YPrPb instead of RGB is the large amount of saved bandwidth. In the RGB signal the luminance component is carried three times. Typically, the color components are about half the bandwidth of the luminance component. Therefore about 4 Mhz of the necessary RGB bandwidth of about 12 Mhz can be saved.
The luminance image (Y) will usually be transmitted 25 or 30 times per second, while the two difference signals will alternate at half that rate.
In the receiving unit the signal is matrixed and the original information is available again.

Y is luminance, U and V are the color differences: U = R-Y, V = B-Y