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Subject: Re[3]: [cgmo-webcgm] Drawing model (take 2)

At 02:32 PM 4/20/2006 -0400, Benoit Bezaire wrote:
>Note, if it were up to me, I wouldn't put any examples at all (it's
>too much).

I would support this -- remove the examples.

Thanks for the history (Porter-Duff).  Interesting.

Correct me if I'm wrong, but it (your equations presented with pre-mult 
input assumption) doesn't imply what functionality is present or how it is 
parameterized in the metafile, but rather just how it's effect is described 
for viewers.  Right?

I.e., when we say ...

>Yes,  Esc.45 is not premultiplied.

what we're really saying is that the equation takes as input non-pre-mult 
RGB coordinates (regardless of how they are stored).  But we don't mean 
your equations to imply, in a RGBA metafile for example, that the R, G, B 
are premultiplied.  I.e., R,G,B are NOT premultiplied in the metafile 
content.  But a processor would premultiply them before applying the 
compositing equations.


(I just re-read the RGBA Registry item -- no hint of pre-mult.)


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