Colour words

[Chris Handley <cbmvax!uunet!GANDALF.OTAGO.AC.NZ!pucc.PRINCETON.EDU!CHandley>]

Bruce writes

> Now, my own usage of the term "purple" is probably closer to
> Dave's than to Chris's, but Chris's usage seems to be the one used
> by color theorists (as he states). I would probably refer to the
> "purples" of color theory as "magenta" -- but I think also that
> most people's "red" includes some magentas and that their "orange"
> could often include what color theorists call "red."

> Any comments?

Th neat thing about use of aids such as the CIE diagram is that it
gives a consistent context within which to talk about colours, and
to plot relationships between colours, hues, saturation,
complementarity, etc. Incidentally shows why 30-colour theories for
either the production or perception of colour are fatally flawed.

As to magenta, this has, or should have a precise meaning. Along
with cyan and yellow, it is one of the three complementary colours
to the ubiquitous red, green and blue of most modern colour
production. As such it can be found very easily on a colour diagram
- locate the points corresponding to your favourite versions of blue
and red, (specs for these are available), join them to white, bisect
the angle between them and project that line to the periphery. That
point will be magenta in your system. To misquote JC Superstar

   "We both have magenta, is mine tha same as yours?"

Chris Handley                                    chandley@otago.ac.nz
Dept of Computer Science                       Ph     (+64) 3-479-8499
University of Otago                           Fax     (+64) 3-479-8577
Dunedin, NZ