[old_tv_nut]

(Raising his hand)

I have explained some of these in multiple threads, but since it's hard to find it all, let me summarize directly in response to your questions.

The original phosphors in the 15GP22 and 21AXP22 were very carefully matched by the color filters used in the TK-41 cameras. In fact, this is one of the reasons the TK-41s needed so much light - the spectral response was adjusted by some "trimming" filters that attenuated the light quite a bit, but made the hue at the center of the filter response correspond to the hue of the phosphors as closely as possible.

The design of the tk-41 spectral response also followed a long tradition of design for film and graphic arts processes, in that the overall filter bandwidths were small and thus emphasized differences in spectra between different objects, thereby increasing the color saturation. The result of all this was that direct applicaton of the R, G, and B signals to the CRT gun currents could be made without any significant electrical matrixing to increase saturation or change hue. (Slight adjustments could be made by the receiver color and 'tint' controls, even though those are at the wrong point in the system due to the non-linear 'gamma' of the CRT guns.)

If the responses of the camera do not correspond to the phosphors well, the proper place to make corrections is to the linear RGB signals in the camera, before the non-linear gamma correction is applied.

The first departure from correct colors was the introduction of sulfide blue and green phosphors. The sulfide blue is more violet than NTSC blue. This means that the complementary color (yellow) has to be greener to make the specified white/gray color. This change was mostly ignored in TV receiver design as far as I know. The change to sulfide green produced noticeable differences in color due to its yellower color. This would move yellow back away from green, and is probably why the change in blue could be ignored. However, the yellower green meant that the spread of color from red-orange-yellow-green was reduced and looked unnatural.

The proper way to fix this would be to insert a linear matrix in the camera; but there was no standardization of just how yellowish the sulfide greeen would be. FCC rules simply said the signal should be "suitable" for the original phosphors. Also, TK-41s were notably noisy, and adding a matrix would increase the noise. There was also a question of maintaining color balance stably with such extra stages in the video processing. So, until Plumbicon cameras came along in the mid 60s, the only live sources were TK-41s with optics tuned for the original NTSC phosphor colors.

Each TV manufacturer played with the matrixing (color demodulator gains and angles, which have the same effect) to approximately compensate for the new green phosphor. Since the new green is yellower, that means that turning on green is also like turning on a little red. The way to fix this is to increase the gain of the (R-Y) demodulator, so it turns off the red more thoroughly when (R-Y) is negative; so, as green increases, red is decreased to compensate for the extra red in the new green phosphor. This would work perfectly if it was used on linear signals; but in the receiver it is being used on the gamma corrected signals which then get applied to the very non-linear CRT guns. The result is that on saturated red objects, the red gun gets turned ON extra hard, resulting in overly bright reds. So, while medium colors were approximately correct, strong colors had significant errors.

Meanwhile, CRTs with the new phosphors were being standardized for studio monitors; at the same time, cameras with more efficient prism optics and different pickup tubes were developed. The studio monitors were built with a switch to turn the approximate matrix on or off, so they could be calibrated electrically with the matrix off, and then would give an approximation of correct color similar to home sets with the matrix switch on.

The more efficent camera designs had wider optical pass bands, which meant they did not naturally produce fully saturated colors required to drive either the NTSC phosphors or the new ones. So, linear matrices were introduced in the cameras to correct the color rendition. At this point, the whole NTSC system was an approximation, and while the correct camera matrix could be calculated, it is certain that there was final visual judgement on the new CRT monitors to see if the matrix should be tweaked a bit. It was like the train leaving the station when the factory whistle blew, while the factory time keeper set his clock when the train left.

PAL put a stop to this nonsense by standardizing to the new receiver phosphors and doing linear matrixing in the camera to match them. NTSC never standardized anything. It is likely that the strength of correction in receivers has been decreasing over time as the tweaking of cameras has occurred, but that is a highly individual design choice of each TV manufacturer.

Adjustment of color was always needed when converting between PAL and NTSC. It's not clear if this always happened outside entertainment material involving enough money and time to be careful.

HDTV has, worldwide, standardized on the modern phosphors. HDTV color rendition is now very stable and repeatable, with material being exchanged between different places based on the same color standards (ITU-R REC 709). These primary colors have also been standardized as sRGB for still cameras and computer monitors. This is the default colorimetry for jpg images and web applications, many of which don't bother to read any information about what standard was used to produce a file.

The most noticeable drawback of the modern phosphors is a lack of highly saturated true greens ("kelly green") and especially of saturated cyan colors. For example, some cigarette packaging is inside the NTSC gamut but outside the modern gamut - but cigarettes are no longer advertised on TV anyway.

Any HDTV material (Blu-Ray) and probably most SDTV (DVD) material has been adjusted for rendition on a modern monitor. This means that when played back on a 15GP22 or 21AXP22, you may see the saturated greens and cyans, but that's not what the studio colorist saw and adjusted for. If he had a wide-gamut monitor, the source was processed to limit its color to Rec 709 so that he saw what people would see on their modern HDTV at home.

There are some computer monitors with wider gamut available, but unfortunately not built to any one standard yet. Most have a green approaching NTSC green, and usually have a red deeper than NTSC red, and an even deeper blue than the non-NTSC modern blue.

There are also some semi-standard wider color spaces, usually associated with photography applications, such as Adobe RGB and prophoto RGB. Taking pictures in camera raw mode allows matrixing the color to any of these spaces, which can have advantages for printing or displaying on a wider-gamut monitor; but many non-aware applications, like common web browsers, will mess up the colors if the files are not converted to sRGB before posting.

There are some proposed standards for expanding the color range that can be carried by digital TV signals, particularly on recorded media (Blu-Ray, DVD), but not all makers agree this is proper. As far as I know, no material has been released with a wider range.

There are some flat panel TVs that have some expanded saturation capability by using a fourth pixel color (yellow), but there is no legitimate source material to watch on them at this time.

Digital cinema has standardized (at least for now) on a wider gamut than the modern phosphors, so the source material shown at theaters has been adjusted to use and accomodate the wider range. A different matrix is used to produce the rec709 file for Blu-ray and DVD distribution