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Date: Fri, 18 Apr 2008 08:53:28 -0400
From: Edward Lam <edward@sidefx.com>
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To: Bob Friesenhahn <bfriesen@simple.dallas.tx.us>
Subject: Re: [Tiff] a question about creating transparency of the image in TIFF
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Status:   

Bob Friesenhahn wrote:
> On Thu, 17 Apr 2008, Chris Cox wrote:
>> Also, the TIFF spec. states that images with associated alpha 
>> (transparency)
>> must be premultiplied.
> 
> The TIFF specification does not prevent a colormapped file with 
> transparency but the colors in the colormap would then need to be 
> premultiplied, which could be a challenge to surmount.  As a result, no 
> one does this.

Sorry, I don't understand this. We output TIFFs with premultiplied RGB 
colors and associated alpha. How is this a "challenge"?

-Edward
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