Colo(u)r sense

[Joshua T]

st. writes:

>As far as I can tell, there is no mauve (or any other
>colors that require combinations, such as white) on the
>electromagnetic spectrum--the closest is violet which is a very dark
>(as perceived by us) frequency range.

Here's how I think I understand it now.  There's no mauve on the spectrum
(there's a spectrum picture with far more plausible violets, on my screen
anyway, than the other one I cited, at
http://home.att.net/~B-P.TRUSCIO/SPECTRUM.gif ).  We see mauve when we get
some combination of red and blue wavelengths (or get our red and blue
receptors stimulated in some ratio, if that's not the same thing).  But
there are lots of colours, like yellow, that we'll likewise see if we get
some combination of wavelengths (e.g., red 55Onm and green 65O nm?), so
mauve is not so special that way, although I think (please correct me if
I'm wrong) that yellow also comes in just yellow wavelengths.  Brown too is
not on the spectrum, but I'm not inclined (as I think susanargus was) to
say that it or mauve or magenta doesn't exist or isn't real.  Solar vs.
electromagnetic?  Maybe Robert's point was that all these colors that I
think aren't on the ("visible"?) spectrum can get produced by combinations
of wavelengths of colors that I think are on it, so they're sort of on (or
in) it too.  (Robert: If cyan and magenta are on it as I think yellow is,
each in a sort of discrete, if fuzzy, sort of single band, please say
where.)  Maybe people consider mauve special because there weren't any (or
not many) mauve things around before Perkin; it would be in that sense (and
in contrast to brown) a nonnaturally occurring color.

Thanks very much for
http://www.cs.brown.edu/research/graphics/research/illus/spectrum/spectrum3.html

It's excellent!

Josh