Quote:
Originally Posted by pidade
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I understand, because of the transition in the '60s to using dimmer, less saturated phosphors in monitors and TVs than those specified by the NTSC in 1953, receivers had to adjust Y'IQ decoding (or did they alter R'G'B' values after decoding?) to produce a more palatable image, and cameras made similar adjustments to the linear RGB values before Y'IQ encoding.
In today's world, where we're obviously not receiving NTSC transmissions directly from a TK-41, but at best, watching a VHS or LaserDisc that was probably seen/mastered on a P-22/SMPTE-C phosphor monitor from at least the '80s, is this still relevant? Was this ever an issue with home/consumer video or just with live broadcasts, where encoding for NTSC phosphors was required by the FCC? How can one tell whether their monitor or TV is altering NTSC signals with its own, subjective matrix, or is there even such a thing as unaltered, accurate NTSC in practice? It all just sounds so chaotic, haha.
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1) "dimmer, less saturated" is not a good blanket description. Green became yellower. Blue became more violet and saturated. Red became brighter but more orange and less saturated for a few years when sulfide red was used, then was restored to close to NTSC with rare earth reds.
2) Receivers adjusted the R-Y, B-Y, G-Y decoding, but not right away when the phosphors first changed. You can see the difference in successive RCA chassis. Electrical coding of the chroma was always per FCC, even for PAL transmission, which matrixed the R,G,B linear signals differently before gamma correction to R',G',B'.
3)The CTC-100 with 15GP22 is the only set guaranteed to have both NTSC decoding and NTSC phosphors. CTC5 and some successive RCA chassis have NTSC decoding, but the phosphors may differ. 21AXP22 and 21CYP22 CRTS may have NTSC phosphors, but that needs to be measured to verify, because the introduction of sulfide blue is not clearly documented. Sets I saw at the Museum of Science and Industry in the late 50s had suspiciously violet blues and greenish yellows, which you would expect from a more-violet blue phosphor combined with NTSC decoding.
4) Yes it was very chaotic
5) I suspect that re-issued LIVE programs shot with TK-41 image orthicon cameras, such as the Dean Martin show, may not have been rematrixed in any way, and only had the chroma amplitude and phase adjusted.
Assuming no rematrixing:
The adjustments may have been made looking at a later non-NTSC monitor, but if there was no re-matrixing, receiver controls on a CT-100 could easily reverse any error. Later sets of the same vintage as the program or earlier will accurately reflect what those sets would have shown at the time.
6) Re-issued film programs, like Bonanza, that have been rescanned on later gear, are completely suspect as to whether they show the same color as the original broadcasts on the sets of the time. Subjectively, the color is probably much better because the newer scanners are much improved over the old Vidicon chains in terms of shading and color distortions caused by the Vidicon's nonlinearity.