Colours

["Chris Handley" <cbmvax!uunet!gandalf.otago.ac.nz!CHandley>]

Hi,
Mostly I just sit and watch the controversies fly past, but evry now 
and again I feel obliged to add my pennyworth.

Dave writes that he has restored indigo to his vocabulary and 
thereby increased his perceptions of the blue end of the spectrum. 
However, he then gets a trifle confused between violet and purple. 
If one looks at the CIE diagram (any half way decent reference work 
on Colour Theory, Image Processing or Computer Graphics should 
contain one), then the spectral colours (including violet) lie 
around the periphery, whereas the purples lie on the straight line 
joining the blue and red ends of the curve. They are niot spectral 
colours, but because we cannot see further than red and violet, we 
pretend there is nothing beyond them, so purples are called 'pseudo- 
spectral' colours, just to close the diagram off.

I also agree with one of the other posters, cyan amd magenta are 
vitally important colour concepts and words for them must be tightly 
pinned down. However do not paint yourself into the traditional 
three-colour corner, that way madness lies.

Chris Handley
Chris Handley                                   Dept of Computer Science
chandley@otago.ac.nz                                 University of Otago
                                                             Dunedin, NZ