W3C home > Mailing lists > Public > www-style@w3.org > May 2006

proposal: background-image-alpha

From: Emrah BASKAYA <emrahbaskaya@hesido.com>
Date: Sun, 07 May 2006 12:47:37 +0300
To: "www-style.w3.org" <www-style@w3.org>
Message-ID: <op.s86dhnqc8nstxa@lomarnona>

Sorry if this was mentioned, but I hereby propose the following property:
background-image-alpha: <alpha-image> || <image-alpha-type> || <opacity>

Proposed Idea:
This will allow designers to use a seperate grayscale image / opacity  
value for alpha used as means of defining opacity of the image / color  
defined in background. Color images would be converted to grayscale with a  
standardized algorithm.

The obvious advantage from PNG32 would be abstraction:
*Ability to use different kinds of formats for defining alpha (e.g. jpg  
for background image, gif for alpha)
*Using different bit depths for image and alpha (e.g. 5bit foreground  
image, 3bit alpha)
*Alpha on a color background instead of an image, hence the ability use  
different colors with same alpha.
*Using the same alpha for different images.
*Using the same images for different alpha.

Instead of an image or together with an image, one can use a constant  
opacity value, with the obvious advantage of:
*Not effecting foreground text opacity, without using extra elements.
*And some of the previous abstraction advantages mentioned previously.

Proposed syntax:
background-image-alpha: <alpha-image> || <image-alpha-type> || <opacity>

   value: <uri> | none | inherit
   initial: none

   value: no-pre-mutiply | pre-multiply-black | pre-multiply-white
   inital: no-pre-multiply
   description: This value can be used to apply transparency for  
pre-multiplied images without color shifting when the image used for  
background is on a black or white background.

   value: <alphavalue> | inherit
   initial: 1

I hope this gets you more interested than my rather important but totally  
ignored "generic fallback mechanism for network environments" post.
Received on Sunday, 7 May 2006 09:47:47 UTC

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