If you have the negatives, you can use the darktable module negadoctor.
For that module it would be helpful to have a part of the film base in the picture.
That is what I get using the negadoctor module:

rey_invert.jpg.xmp (5.4 KB)
If you have the negatives, you can use the darktable module negadoctor.
For that module it would be helpful to have a part of the film base in the picture.
That is what I get using the negadoctor module:

rey_invert.jpg.xmp (5.4 KB)