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Re: CIE color definitions in CSS3 color module

From: Chris Lilley <chris@w3.org>
Date: Wed, 29 Sep 2010 20:53:17 +0200
Message-ID: <756699522.20100929205317@w3.org>
To: Alexis Shaw <alexis.shaw@gmail.com>
CC: www-style@w3.org
Hi Alexis.

I'm one of the editors of the CSS3 Color module, and am just back today from two weeks vacation. I see that you made a comment while I was away - it is being tracked as last call comment 31.

On Friday, September 10, 2010, 4:29:21 PM, Alexis wrote:

AS> I wish to propose the following types of color definitions.

In general I am sympathetic with (and understand) the desire to be able to specify colour in a CIE colour space.

However, the current state of CSS3 color is that is stable, has been around for years, finally has a test suite and passing implementations, and is therefore ready to become a Proposed Recommendation very soon. Indeed ,there was functionality about ICC profiles for images, which was dropped for lack of implementations (in browsers, using that syntax).

We don't, therefore, want to be adding new and unimplemented (in browsers, using a CSS syntax) features at this stage.

Your comments are certainly worthy of consideration and further discussion, but would more appropriately fit with the proposed CSS4 color module.

In particular, being able to specify values in CIE Lab (together with the appropriate white point) would be very handy.

I see that in further discussion, Tab pointed out that this would also require control over the interpolation colourspace as well.

So we would like to reject your comment, as being too late for CSS3, and instead consider it for a future specification. Would that be acceptable for you?

AS> A CIE XYZ color definition.

AS> xyz(x, y, z) where x, y and z are the floating point values of the CIE 1931 XYZ color space
AS>  
AS> along with the corresponding
AS> xyza(x, y, z, a)

AS> A CIE xyY color definition.
AS>  
AS> xyy(x, y, Y) where x, y, and Y are the floating point values of the CIE 1931 xyY color space.
AS>  
AS> along with a corresponding 
AS> xyya(x, y, Y, a)
AS>  

AS> a CIELUV color definition
AS>  
AS> luv(L*, u*, v*, white_point) where L, u, v are the floating point
AS> values in the CIELUV colorspace. the white point term will be defined below. 
AS>  
AS> along with the
AS> luva(L*, u*, v*, white_point, a)
AS>  

AS> A CIELAB color definition
AS> lab(L*, a* , b*, white_point) where L*, a*, b* are the floating
AS> point values in the CIELAB colorspace, white point defined below.
AS>  

AS> The LAB and LUV colorspaces take a white point as a parameter
AS> this may be one of the following values.

AS> One of the CIE standard illuminates
AS> A, B, C, D50, D55, D65, D75, F1-12,
AS>  
AS> the following common illuminants
AS> UL_3000, TL80, A_T8

AS> the following black body format.
AS> xxxxxK

AS> or a custom white point defined by an @whitepoint rule.
AS>  
AS>   



-- 
 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Wednesday, 29 September 2010 18:53:29 GMT

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