[old_tv_nut]

In CRTs, the 15GP22 and 21AXP22 (early ones, at least) had NTSC phosphors. There is some question as to when the blue phosphor was changed in 21 inch tubes. The early 21 inch sets with sulfide (non-NTSC) green had NTSC decoding, resulting in some color errors. If you study RCA's schematics year by year, you can find when the demodulator components were changed to improve reproduction with the non-NTSC phosphors.

In cameras, the TK-40 and TK-41's (image orthicons) were strictly NTSC. This was determined by the optical filtering in the three color channels. There was no matrixing of signals between the red, green, and blue before gamma correction.

When Plumbicon cameras came out, they were much less noisy, and had all solid state circuits, which meant that stable linear matrixing before gamma correction was possible. At this point, the dichroic prisms could be designed for optimum light efficiency and minimum signal to noise, with a reasonable approximation to proper response that could be matrixed before gamma correction to best match either NTSC phosphors or PAL (modern) phosphors. With the optics not tuned to a particular phosphor set, and the capability to adjust the matrix freely, a camera maker might start with a theoretically correct NTSC matrix and tweak it for appearance on the monitors of the day.

When we made the HDTV format test tapes, we went through a process of measuring the cameras and adjusting the matrices to be theoretically correct for HDTV phosphors. We found that the BTS cameras were already correct, but the Sony had a matrix that had been tweaked for a certain "Sony look."

Material that started with TK-41s has NTSC colorimetry on the original tapes, but there is still a question of how much the color was tweaked when the material was restored and transferred to modern media.

The Eisenhower tape as well as the last-day RCA tape from the New York World's Fair on YouTube look surprisingly saturated to me. Maybe the color is as original, and maybe not. One confusing factor is that the TK-41's gamma correction was less than 2.2, resulting in an increase in overall system gamma (contrast) and an increase in saturation, a similar trick to that used by Technicolor and color transparency film. If you want to see how this works, take an image into Adobe Lightroom or Camera Raw and play with the Contrast slider. This apparently works on the contrast of the individual R, G, and B, so when you increase contrast you will also see the saturation increase. (The Highlight and Shadow sliders apparently work in Lab space, and do not affect saturation.)