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Re: CNS colors

From: David Perrell <davidp@earthlink.net>
Date: Thu, 08 Feb 1996 09:07:23 -0800
Message-Id: <199602081708.JAA28417@iceland.it.earthlink.net>
To: www-style@w3.org
At 12:01 PM 2/7/96 +0000, Chris Lilley wrote:
>But you write:
>
>> and I think CNS is a bad idea.
>
>which would be fine if you had a technical reason, but you go right 
>on to say:
>
>> Obviously CNS (which I'd never heard of before) is a subset of the HSB 
>> (hue-saturation-brightness) color model, widely used and intuitive. 
>
>So you have newver heard of it, have a false idea of what it is, and
>confidently state it is a bad idea...

Actually, "I think" isn't all that confident. My point in mentioning my "credentials" was that if CNS had gained widespread acceptance, I would likely have heard of it. In any case, your message corrected a foolish presumption that CNS was being proposed as the primary method for color spec'ing -- a presumption that changed my hue and prompted me to oversaturate my prose. My thoughts have changed, but I'd still like to address some of your comments.

>Perhaps you should have taken the trouble to find out more about it ;-)

Well, it's a lot easier finding out from you than finding a 14-year-old CG&A. ;-) If the paper were readily available to me I'd certainly read it.

>In particular, it has nothing to do with HLS, HSB and suchlike polar
>representations of RGB (which are, in usability studies, often shown to
>be *not* very intuitive).

As described in Hakon Lie's message, CNS colors are distinguished by hue, saturation and lightness. To me, a conceptual relationship to HSB, HLS, and Munsell is implicit.

>I am sure you are also aware that many of the Pantone spot
>colours are not withing the gamut of most RGB monitors.
Yes.
>TOYO is not "based on HSB" to the best of my knowledge.
I believe it's an evenly spaced range of hues, with evenly spaced saturations of each.
>Monitors do not use the CMYK colour model.
A technological challenge, to be sure. (Point four guns backwards and suck spectrum from a white screen?)

I was trying to make the point that 627 colors don't adequately address the capabilies of either print or display.

>HSB is a spectacularly bad idea as it is non intuitive.  It claims for
>example that yellow (RGB 00FFFF) and blue (RGB 00FFFF) have the same
>"brightness" which is clearly false.

I see your point, but isn't a fully-saturated yellow brighter (lighter) than a fully-saturated blue (RGB 0000FF)? With CNS, would "medium vivid blue" be as bright as "medium vivid yellow"?

>The overall concept of a polar model (as used for example by Munsell,
>OSA, Itten, NCS, CIE LCH and so on is fine.  The particular
>implementation in HSB is not.

Then I will champion this model no more forever.

>The broadcast industry uses LUV, not LAB

Is it still YIQ for NTSC?

>Indeed, the reason I suggested CNS is that it may be unambiguously 
>related to CIE colour spaces.

Sounds good. I'd still argue it should index a finer-resolution color specification. And still wonder how many of those usenet complainers will be hand-coding color a year or two hence.

Apologies for my inaccuracies. Thanks for your corrections and clarification.

David Perrell

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Received on Thursday, 8 February 1996 12:08:21 GMT

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