Photographic dust

You can't use alcohol ~ ~ ~ or your photos will fade where they have been stained with alcohol.

Because photo printing is a process of chemical change, it is best not to use chemical methods for further processing.

You can try to rub it gently with an eraser. If the stain is light, it can be removed. Remember, wipe it gently, not too hard, or it will damage the surface of the photo.

Or you can adopt a new method.

Professional high-precision scanning, computer repair after scanning, and then redrawing.