I know from the world of astronomical digital imaging, where the idea
of displaying true color was long ago given up, that color is now
agreed to be perceived. What is perceived as true color, amazingly
enough, varies culturally. For instance, if you ask an American to
select from memory, the true color of the blue sky, the true color of
grass, the answer will be different from an European or a Japanese
answer. In general, the answers will tend to be more blue for the sky
color, and more green for the grass color, than measured with a
photometer from the real nature. If you grab a Japanese magazine, and
look at their ads, (their mags tend to be better produced than
American ones, by the way, with beautiful photos and production
values) you may see the color differences.
In astronomical imaging, we are faced with very narrow emission lines
that straddle colors. Depending on filter set and sensitivity, the
color returned by the digital camera might be blue or might be green.
How do we depict an emission line that is between blue and green, but
slightly more to the blue? How would we perceive it if we were
floating in space right next to the nebula, as opposed to being a few
hundred light years away?