Re: [Gimp-developer] deriving transform by comparing image before/after edit

[Alexandre Prokoudine <alexandre prokoudine gmail com>]

Hi Bill,

I don't know of plugins that would calculate a matrix in GIMP. There's
a plugin called GetCurves by Elsamuko [1] that calculates a rough
approximation of a color transform between two layers and creates an
RGB curves preset.

Due to its nature, the plugin has obvious issues treating different
hue ranges differently [2] but maybe it's a motivation for someone to
come up with a better tool. Although I'd be damned if I knew how you
would then apply a generated 3x3 matrix to a different image :)

I recently looked at free/libre options to create 3D LUT files, and
the existing options like Harlequin [3] are not very encouraging yet.

[1] https://github.com/elsamuko/gimp-elsamuko/tree/master/plugins/elsamuko-get-curves
[2] https://twitter.com/lgworld/status/1338597821881192448
[3] https://github.com/dunkyp/harlequin/

Alex

On Sun, Dec 27, 2020 at 2:47 PM Bill Ross via gimp-developer-list
<gimp-developer-list gnome org> wrote:
> Given a pair of before/after jpeg photos edited with global-effect
> commands (vs. operations on selected areas), is it possible to derive
> transformation matrix/matrices that reproduce the result from the
> original? Presumably by iterating over all the pixels in a 1:1 mapping.
>
> My hope is to train neural nets to predict the matrix operation(s)
> required. Example:
>
> http://phobrain.com/pr/home/gallery/pair_vert_manual_9_2845x2.jpg
>
> Thanks,
>
> Bill
>
>
> --
> Phobrain.com
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