Facts : 1 Color video signal extraction Color bar generator test signal A color signal conveys picture information for each of the red, green, and blue components of an image (see the article on color space for more information)
Facts : 2 However, these are not simply transmitted as three separate signals, because: Such a signal would not be compatible with monochrome receivers (an important consideration when color broadcasting was first introduced); it would occupy three times the bandwidth of existing television, requiring a decrease in the number of television channels available; and, typical problems with signal transmission (such as differing received signal levels between different colors) would produce unpleasant side effects
Facts : 3 Instead, the RGB signals are converted into YUV form, where the Y signal represents the lightness and darkness (luminance) of the colors in the image
Facts : 4 Because the rendering of colors in this way is the goal of both black and white (monochrome) film and black and white (monochrome) television systems, the Y signal is ideal for transmission as the luminance signal
Facts : 5 This ensures a monochrome receiver will display a correct picture in black and white, where a given color is reproduced by a shade of gray that correctly reflects how light or dark the original color is
Facts : 6 The U signal is the difference between the B signal and the Y signal, also known as B minus Y (B-Y), and the V signal is the difference between the R signal and the Y signal, also known as R minus Y (R-Y)
Facts : 7 The U signal then represents how purplish-blue or its complementary color yellowish-green the color is, and the V signal how purplish-red or its complementary greenish-cyan it is
Facts : 8 The advantage of this scheme is that the U and V signals are zero when the picture has no color content
Facts : 9 Since the human eye is more sensitive to errors in luminance than in color, the U and V signals can be transmitted in a relatively lossy (specifically: bandwidth-limited) way with acceptable results
Facts : 10 In the receiver, a single demodulator can extract an additive combination of U plus V
Facts : 11 In that same system, a second demodulator, the Z demodulator, also extracts an additive combination of U plus V, but in a different ratio
Facts : 12 The X and Z color difference signals are further matrixed into three color difference signals, (R-Y), (B-Y), and (G-Y)
Facts : 13 The combinations of usually two, but sometimes