Re: [Gimp-developer] Masks not very effective in 2.9 scheme script

[Ken Moffat <zarniwhoop ntlworld com>]

On Sat, Jul 15, 2017 at 08:21:32AM -0400, Ell via gimp-developer-list wrote:
> On Tue, 11 Jul 2017 00:38:17 +0100
> Ken Moffat <zarniwhoop ntlworld com> wrote:
>
> > Hi,
> >
> > TL;DR - using masks in a 2.8 scheme script works as intended to
> > extract parts of an image, but after converting it for 2.9 it does
> > much less.
>
> The most likely reason for the different results, is that in 2.9 masks
> use the pixels' linearized intensity as the alpha value, while in 2.8
> they use the gamma-corrected intensity.  The linearized intensity
> values are generally lower than the gamma-corrected ones, so the
> resulting mask values, after pasting a desaturated image into the mask,
> are lower in 2.9 than they would be in 2.8, resulting in a subtler
> effect.  Note that these sorts of interactions is something we're still
> working on.

Thanks for the detailed reply.  I'll have to get back on the 2.9
machine at some point to work through the options.  Meanwhile, I've
saved a full copy of your mail in my notes.

Cheers.

ĸen
-- 
I live in a city. I know sparrows from starlings.  After that
everything is a duck as far as I'm concerned.  -- Monstrous Regiment