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Originally Posted by pidade
... Literally couldn't find any information about modified NTSC decoding outside of a vague mention here or there in a couple ITU or SMPTE papers, though it seems kind of significant.
Was there ever a standard set for this modified decoding, considering the phosphors used were generally fairly consistent across different tubes from the '70s onwards? I also wonder how white balance affected it (FCC specified CIE Illuminant C, SMPTE specified D65, TV manufacturers generally went for ~D93).
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Some papers on modified chroma decoding were published in the IEEE Transactioins on Broadcast and Television Receivers.
The SMPTE-recommended switchable matrix for monitors was the only standard one I know of. TV makers did their own thing, based on their own subjective views. One of the things that affected the TV makers decision was the decidedly cyan white balance of receivers for many years. The subjective effect of white balance is dependent on surround conditions, which vary greatly in the home. The effects are much smaller in a dark theater environment with a screen occupying much of your view.
Referring to it as D93 is incorrect, as the D series of daylight colors had not been established. It was labeled as 9300K + 27 mpcd. This means it coreesponds to a black body color at 9300K and an adjustment perpendicular to the black body locus towards blue-green by 27 minimum perceptible color differences. It really was Illuminant C with the red reduced, so it was off the daylight locus toward cyan. This was strictly a measure to reduce the ratio of red gun current to the other guns, as obtaining daylight color ran the risk of spot blooming in the red highlights. Professional monitors could get away with actual daylight white (and unequal beam currents) because they weren't intended to be searchlight-bright in a store showroom. Not all manufacturers used 9300K. One of Zenith's secrets was its specified white point, which was less blue than others. Some manufacturers (Mitsubishi large screen rear projectors in particular) maintained the extreme cyan white balance forever, even when most others were offering a customer choice of a cool or warm (at least not so blue) setting.