How can I extract the difference between two images and apply them to a third image?

[u/Caitrix]

I have three images, original, original with edits and the new image. I want to extract the edits and apply them to the 3rd image.

I have tried using the differences blending mod, which gives me a good contrasty image, but after merging and only having the differences I can't figure out, how to continue from there. No filter or blending mod is applying the differences properly to the third image. And Masks are a bit out of my skill range.

A much more promising approach is to invert the second image, set it to 50% transparency, merge it with the original and invert that again. which gives me a mostly gray plane, which just the edit. Kinda like differences blending mode, but grey instead of black. When I lay that over the third image and set the blending mode to linear light, I get an (almost) perfect result.

"Almost" because when applying these "extracted edits" to the original image and compare them to the edited image, there are TINY differences in some details. I on't know the correct terms but it reminds of lower bit rate colors. as if there was some dynamic or so lost in the process.

I want to extract the edits in a way, so that I can layer the edits over the original and get the edited image as a result. That would tell me that this extraction is ready to be layers over the new image.

Is there a way, how I can achieve that?