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Re: [css3-images] Resolving on gradient issues

From: Alan Gresley <alan@css-class.com>
Date: Thu, 11 Aug 2011 14:23:07 +1000
Message-ID: <4E43592B.4060407@css-class.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: www-style list <www-style@w3.org>
On 4/08/2011 9:50 AM, Tab Atkins Jr. wrote:
> On Wed, Aug 3, 2011 at 4:32 PM, Alan Gresley<alan@css-class.com>  wrote:

>> Since you would like to move the spec to LC and would like vender prefixes
>> dropped from gradients, can the LC reflect the current implementation of
>> WebKit and Gecko for gradient with alpha transparency to be done in
>> non-premultiplied. The reason are.
>
> Opera and IE both render gradient in premultiplied space as the spec
> requires.  This is sufficient for the issue to not hold up CR.


IE10 preview is not a release version of IE for the general community. 
Are you aware when such a general release version of IE10 would appear? 
Only Opera 11.50 has been released to the general community which 
supports gradients to alpha transitioned in premultiplied space.

That means two release versions of particular engines support gradients 
to alpha transitioned in non-premultiplied space and only one release 
version of particular engine support gradients to alpha transitioned in 
premultiplied space.



>> 2. I believe a syntax change or possibly prgba() can be used as a trigger
>> gradients to premultiplied space where there is alpha.
>
> I don't believe we should select the color-space based on the syntax
> of the colors used, because a color should be independent of the
> syntax used for it.  Instead, I believe this should be done either by
> defining SVG's color-interpolation property to apply more widely to
> all CSS values, or by giving gradients a specialized switch to control
> the color-space they transition in.  I'll address this in a later
> level of Image Values.


How about this.

   linear-gradient(white, pre-transparent)


> (I also think it would be useful to transition in hsl space, for
> example.  If we make hsl() the trigger for this, what happens if you
> mix hsl() and prgba() colors?  Any answer is arbitrary.)
>
> ~TJ


Good point.

May I add that HSL space has a direct relationship to sRGB space since 
there are HSL planes in sRGB space and this is non-premultiplied space.

What you see here,

http://upload.wikimedia.org/wikipedia/commons/1/16/CIE1931_rgxy.png

are only colors in premultiplied space.




-- 
Alan Gresley
http://css-3d.org/
http://css-class.com/
Received on Thursday, 11 August 2011 04:23:23 GMT

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