Signals used by colour television systems to convey colour information (not luminance) in such a way that the signals go to zero when there is no colour in the picture. colour difference signal formats include: R-Y and B-Y; I and Q; U and V; PR and PB. The figure below shows general colour difference waveforms along with the Y signal. The colour difference signals must first be converted in their RGB form before they can recreate the picture. Refer to the RGB discussion to view what the RGB version of the colour bar signal looks like. The colour difference signals in the figure are centred around 0 volts, but this is only true for the SMPTE/EBU N10 standard. The NTSC and M11 colour difference standards have the most negative portions of the colour difference signals riding on a voltage of 0 volts or close to it.