Am 11.01.2016 um 04:09 schrieb Kenneth:

>> In your case, you'll want to use "premultiplied off".
> 
> Yes indeed, that does eliminate the 'hard-edged matte' quirkiness of my
> fading-out TIFF image. Thanks for pointing this out. I'm embarrassed to admit
> that I *did* read about the new 'premultiplied' keyword-- then promptly forgot
> about it.  :-(  I just gave the docs there a good re-reading!  I actually wasn't
> sure *why* it was necessary, until now. What a big difference it makes!

No reason to be embarrassed: People just forget about stuff if they
don't know what it's good for.

> So all that remains is to find a fix for the previously-mentioned 'transmit all'
> transparency problem, with its erroneous complementary colors etc.  ;-)

Working on it; there's a catch to it though: Currently the injection of
the "transmit all" component happens before compensating for whatever
gamma mode is used in the image. I'll need to wrap my head around the
implications for the formula, or move it someplace else.


> Thanks again for taking the time to explain this complex situation so well.

You're welcome.

By the way, would you mind posting your TIFF test image? The tools I
have at my disposal to quickly create a TIFF with alpha channel all give
me the other alpha mode.

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