The primary colours (was Re: YAEPT: "year" (sorry!) (was Re: Why "y" ain't arbitrary (was: Intergermansk - Traveller's Phrasebook)))

On Sun, 06 Feb 2005 16:45:37 -0800, Gary Shannon <fiziwig@...> wrote:

> Anyway, artists call the three primary colors red,
> yellow, and blue while physicists (and computers) use
> the primary colors red, green and blue and printers
> will tell you that the primary colors are cyan,
> magenta, and yellow.  So what ARE the primary colors?
The three additive primary colours are red, green and blue -- that is,
these are the primary colors of light, they correspond notionally to three
specific wavelengths of light. The three subtractive primary colours are
cyan, magenta, and yellow -- these are the primary colours of pigment,
they correspond notionally to the absence of reflectivity at those same
three frequencies.

Cyan and magenta are easiest to explain to persons without a background in
colour technology as blue and red respectively, and indeed subtractive
cyan and magenta do look quite blue and red absent context -- have you
ever looked at any amount of pure inkjet printer ink? This is where the
common confusion begins. It's not a case of the physicists' and the
artists' primary colors having two elements the same, and one different,
but rather of their having confusingly identical names for two pairs of
actually quite different colours.




Paul