Return-Path: 18 Jun 91 16:18:03 +1200 Message-Id: X-To: lojban-list@snark.thyrsus.com From: cbmvax!uunet!gandalf.otago.ac.nz!CHandley Date: 18 Jun 91 16:16:27 GMT+1200 Subject: Colours X-Mailer: Pegasus Mail/Mac alpha 8 Apparently-To: Status: RO X-From-Space-Date: Tue Jun 18 03:29:05 1991 X-From-Space-Address: cbmvax!uunet!gandalf.otago.ac.nz!CHANDLEY Hi, Hope this gets thru, I am testing my access to the discussion and my new mailer. I have been reading most of the discussions about a variety of topics with great interest, but have not had time to respond - actually I still don't, but what the heck, I could not let the discussion about colours go un-answered. The 3-colour theory of colour production, whether with paints or with lights (filters, phosphors or whatever) admits that you cannot produce all colours that way, a fact that is usually conveniently forgotten. If one looks at the colour space produced by the CIE, one can see that it looks something like a parabola lying on its side. Using three colours one can only produce the colours within a triangle. Thus, even if one used spectrally pure green, red and blue (whatever that may mean), one could not produce the other spectrum colours, nor the psuedo spectral colours along the purple line. This then raises the question of how many colours there are along the spectrum and how do you name them. That I cannot answer - 'English' recognises 7, other languages/cultures undoubtedly recognise a different number. At a bare minimum however, from a purely practical point of view, we need separate names for the three primaries (red, green, blue), the three secondaries (cyan, magenta, yellow) and the two mixtures (black and white). What you do about the rest comes down to theology, in the same way as naming the elements - what are recognised as distinct and what are useful for every day conversations. Chris. (My employer couldn't give a damn what I say)