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Re: [css3-images] Premultiplication switch

From: Alan Gresley <alan@css-class.com>
Date: Mon, 01 Aug 2011 12:04:27 +1000
Message-ID: <4E3609AB.2020702@css-class.com>
CC: "www-style@w3.org" <www-style@w3.org>
On 1/08/2011 12:26 AM, Alan Gresley wrote:
> On 31/07/2011 7:21 PM, Brian Manthos wrote:

> OK, good. I guess you may have not seen this HD photo format that has
> prgba. See page 8.
>
> http://download.microsoft.com/download/a/f/d/afdfd50d-6eb9-425e-84e1-b4085a80e34e/cln-t374_wh07.pptx


Offlist, Brian pointed me to this color format.

<http://msdn.microsoft.com/en-us/library/system.windows.media.pixelformats.pbgra32.aspx>

> Pbgra32 is a sRGB format with 32 bits per pixel (BPP).
> Each channel (blue, green, red, and alpha) is allocated
> 8 bits per pixel (BPP). Each color channel is
> pre-multiplied by the alpha value.


This may be one option but it would mean the introduction of potentially 
two formats for CSS4 color. They being prgba() and phsla().

I would believe that gradients done with prgba() could not be 
transitioned to rgba() or gradients done with phsla() could not be 
transitioned to hsla().

The benefit would be that both types, pre-multiplied and 
non-premultiplied gradients could share the same syntax without having 
to add some form of switch.



-- 
Alan Gresley
http://css-3d.org/
http://css-class.com/
Received on Monday, 1 August 2011 02:04:55 GMT

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