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

Thanks Alexandre!

I figured I'd most likely be writing the code if the math is possible - 
it would start as a standalone batch prog that could be appified. But 
I'd need an obvious path to even start, since I'm more of a 
jack-of-all-trades programmer, e.g. not sure how close LUTs could come.

I realized it would be capable of reverse engineering any global 
filters, so could irk anyone who makes money from them.

Here's where I tried the question earlier:

https://www.reddit.com/r/computervision/comments/kktdq4/derive_transformation_matrix_from_two_photos/

My current editing backlog is 150K photos.

Bill


On 12/27/20 4:06 AM, Alexandre Prokoudine via gimp-developer-list wrote:
> 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
> <[email protected]> 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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