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All these things are fun to play with, but you need 3 separate signals to get true color TV. At the TV studio you start with R, G, B. That's converted to Y, U, V or Y, I, Q or Y, R-Y, B-Y. As the human eye's ability to distinguish differing color detail is about jalf that of differing brightness detail levels, Y is twice the vertical and twice the horizontal resolution of U or V. So we save some bandwidth with this conversion. At the TV set, the chroma subcarrier (which is a quadature AM signal, U is sine, V cosine gives us the R-Y and B-Y or UV or IQ. Then add Y to R-Y and you get R, same for B. What about the green? Well, if you invert R-Y and multiply by a coefficient, and invert B-Y and multiply by another coefficient (so you'd get a vector pointing "southwest"), That becomes G-Y. and add Y and you have green. RGB.
The above Mexican schemes only have 2 signals, roughly a red signal, and the 2nd is a cyan signal. No luma only. Thus you can never get true RGB from just that.
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