I could use some tips on restoring a scanned print of a family photograph from the 1930s. The photo is heavily scratched, but I would like to restore as much as possible. Any tips on removing the texture of scratches on the image? The foreground is very soft and I would like to improve definition and detail.
I took Nathan's image as a baseline then used Wavelet Decomposition with a rough select around the people to duplicate two layers of detail and re-merge it back in to try to sharpen without producing the sharpen artifacts you get from unsharp mask.
Per a request for methodology details:
I used GIMP 2.10
Layers Scale 2 through 5 and residual follow. (Scale 1 has almost no information).
I duplicated layers scale 3 & 4.
I also selected just the people and deleted everything else in the duplicated layers to apply the sharpen effect to just the people. Not Shown.
Besides a sharpen effect from duplicating layers, the reverse can be accomplished by deleting layers or painting gray over various level details in the wavelet decomposition to selectively remove different levels of detail, effectively blurring. You can even blur gross detail while keeping fine detail.
Editing just the residual can help remove color stains without impacting details.
Here is my image after removing major scratches and defects. I tried playing around with whole-image FFT to remove finer scratches and texture but could not find a good way to keep foreground details (e.g. hair, skin edges, etc.). This was VERY meticulous use of heal brush, and I don't have the patience to heal brush every scratch in this image.