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[css4-color] Re: CIE color definitions in CSS3 color module

From: Christoph Päper <christoph.paeper@crissov.de>
Date: Thu, 16 Sep 2010 20:50:41 +0200
Message-Id: <5FB69A56-81F7-41E5-ACE0-6931FBAFDCD5@crissov.de>
To: "www-style@w3.org list" <www-style@w3.org>
Alexis Shaw:
> On 11 September 2010 21:49, Christoph Päper <christoph.paeper@crissov.de>wrote:
> 
>>> xyz(x, y, z)
> 
> X, Y and Z colours are normalised as values so that Y is between 0 and 1 in
> the ICC profile standard, and between 0 and 100 in the CIE standard. this
> means that X and Z can be reasonably be in [0,2) and [0, 200) respectively.

Hm, I’d like them all to be positive percentages, like most other color components are or can be (excluding hue which is an <angle> and alpha which is a percentage but written as a float in [0, 1]); or X and Z could be translated to signed percentages (i.e. subtract 100).

All the other proposed parameter values obviously can be represented by either positive percentages (probably exceeding 100%) or signed percentages without breaking preexisting habits. I hope no-one wants to repeat the <alpha> disaster.

>> Is it important to have the whitepoint specified by the author or could CSS
>> safely select one?
>> 
>>> or a custom white point defined by an @whitepoint rule.
>> 
>> What properties / descriptors would this have?
>> 
> 
> all white points can be defined as a color in the XYZ color space.

Then ‘@whitepoint’ would essentially be a way to specify a color and ‘white_point’ in ‘luv()’ and ‘lab()’ essentially is just a color? I’ve just proposed to be able to define just that in a separate message.
Received on Thursday, 16 September 2010 18:51:14 GMT

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