ITWissen.info - Tech know how online

color-difference signal

Color difference signals are color signals formed from the primary colorsred (R), blue (B) and the luminance signal (Y). In television, there are the color difference signals B-Y and R-Y. From them and the luminance signal, the color signals for red, green and blue can be obtained.

In the PAL television standard, the U signal and the V signal are obtained from the two color difference signals - R-Y and B-Y - for transmission reasons. Their level is reduced and their video bandwidth is limited to 1.3 MHz compared to the color difference signals.

Relationship between luminance and color difference signals

Relationship between luminance and color difference signals

The U signal contains the color difference blue- yellow and corresponds to the (B-Y) signal reduced by a factor of 0.493, the V signal contains the color difference red-turquoise and corresponds to the (R-Y) signal reduced by a factor of 0.877. They contain the chrominance and, unlike the luminance signal, are transmitted with a lower bandwidth. In NTSC, these signals are designated "I" and "Q". The color difference signals are used in conjunction with color subsampling for data reduction, for example in JPEG.

There is a direct mathematical relationship between the color difference signals, the luminance signal and the primary colors (R), (G) and (B): U = 0.49(B-Y), V = 0.88(R-Y). The digitized U signal is also referred to as "Cb" and the digitized V signal as "Cr". "Cb" and "Cr" are used in the ITU standardBT.601 for digital video. "Cb" corresponds to the color deviation blue-yellow and "Cr" to the color deviation red-turquoise.

Informations:
Englisch: color-difference signal
Updated at: 14.06.2012
#Words: 246
Links: color, blue (B), luminance (Y), signal, indium (In)
Translations: DE
Sharing:    

All rights reserved DATACOM Buchverlag GmbH © 2024