I spend a lot of time on photo editing. There is a big difference between images and text reproduction for printing books. Newspaper text when scanned at 600 dpi will still not print clearly for books. Portraits and photos scanned at 600 dpi turn up sufficiently good in printed books. The text-based images have to be edited separately from the portraits. Photos have to be edited in many ways before they will be good for printing in books. Sometimes photos are too dark and making them "light" destroys even the figures in the photos. Sometimes an artificial background needed to be created as the original background was too dark or of various tones. Sometimes images taken off printed pages are pixelated and beyond what I can manage to salvage for use in my books.
There are many useful tools or software but they have to be tried to see how they can improve photos or images. Portraits are the hardest objects in photo editing.
Here are some tools for photo editing: