Re: 75% bars

[tony salgado] "75% bars refer to saturation when bars are viewed on a vectorscope."


No it does not.


Color Bars are always 100 percent saturated. The 75% refers to amplitude.

To repeat: The number refers to the amplitude of RGB into the encoder. One hundred percent color bars put an undue strain on transmission systems in that the subcarrier peaks for yellow (which sits atop the highest luminance value) go to 130 IRE. Blue, the lowest in brightness has subcarrier that sinks below blanking. But the math for 75% amplitude color bars works out to a signal that reached to just 100 IRE for the positive peaks of the subcarrier signal for both yellow and cyan.





Cheers,

Frank Otto