[old_tv_nut]

Regarding the request the NTSC made for additional slides with strong green elements:
It is well known that fairly satisfactory color images can be made with the Q channel turned off, since skin tones (light or dark) lie on or near the I axis. But the need to keep skin tone hue consistent was known to Kodak as well, resulting in film formulations that suppressed any tendency to shift skin towards green or magenta. As a result, most slides that would have been available would have little strong green or magenta content.

The provision of slides with plants against light and dark backgrounds would also be a substitute for critical shifts in color balance with dark and light subjects including skin tones. This is not to say that the lack of dark-skinned subjects was totally compensated by the range of test slides used. It certainly would have been an improvement to include a range of skin tones. However, there were similar problems in shadow color balance and contrast range in color film. If you review photography texts of the time, it is always stressed that exposure must be adjusted for photos of dark skinned people, and photos of groups with mixed skin colors usually needed careful lighting to not disfavor darker or lighter skin. Simple snapshots with non-adjustable cameras always had variations in skin tone, both White and Black. Professional photographers would control lighting and exposure and also use color balancing filters that were determined by Kodak and specified with each batch of professional film. Even then, precise results could not be achieved with slide film, as the processing could still affect color balance. Precise film color was only achieved in negative/positive processes where the color of the print was adjustable by trial and error. Color TV was held to a much stricter standard, as the off-balance could be adjusted in real time by turning the right knobs.

The problem of precise balance in darker tones was repeatedly raised over the years; advertisers of wood furniture complained when magazine images didn't match what they wanted. Dark skinned people have (rightly) been dissatisfied with the poor tolerance on their skin tones, but it really has not occurred because the problem was ignored, but because it is much more difficult to control the balance of dark tones in film (where dye concentration is max) than light tones.

In movies, the problem was reduced by throwing money (personnel and time for print adjustment) at it.

In television and eventually movies and still photography, the problem has been reduced with each major development in camera technology; first better analog cameras for TV, and then digital cameras for TV, movies, and amateurs.