Hi Bob!

I'm afraid I don't understand so much of what you're saying, but I'll try to
answer what I can.

> If the alpha channel affected antialiased edges of objects in a
> way that the edges were treated as semi-transparent when loaded
> into a post processing program then no matter what background
> the image were pasted over it would mix with it correctly.
> That seems a lot different than what you are suggesting, but
> maybe because I don't know what it is exactly.

The method I describe will make AA work just the way you describe.

> Well, I don't understand how gray is any better than it being
> black or any other color  :-)

Not the background, but the transparency-vector. When that vector is grey
(or black or white) it means that the red, green, and blue components have
the same percentage of transparency, and that's exactly what the
alpha-channel supports. If they don't have the same amount of transparency,
the average of the 3 colour-components will have to be taken. That's not
very good, but there's no better alternative.

> isn't some form of transparency already done in other things
> such as game graphics, paint programs, etc?  I know that in
> PSP it's a simple thing to use a semitransparent image and
> paste it onto another image but there never is a implied
> background color beforehand.

The problem is that the image format is the limitation. They support
transparency, but only the percentage kind of transparency. You will never
see images that contains, say, filter transparency. Therefore all
transparency has to be converted to the percentage kind before it can be
stored in the output-image.

Greetings,

Rune
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