This may be outside your plan, but I really could use a pdf editor that makes Internet Archive book scans more readable.
Apparently, the scanner(s) adopt some compromise setting that renders halftones OK, but gives all text a "dishwater gray" background.
If there are few pictures, I run the PDF through a quartz filter in Preview to threshold the text and later merge graphics pages with the "contact sheet" view from an un-threshold-ed image in Preview.app. This is slow and tedious.
Of course, computers are "smart," so they tell me, and should be able to recognize a picture from a block of text on the same page and render each one appropriately.
I used to do such editing of really important documents (like ads for pioneer computer products and gizmos like GENIAC and such)[0] pretty much by hand, splitting a PDF, if needed, into multiple images and hand/batch editing, then merging again.
I could use ImageMagick ... but it's not adaptive, as described above.
Geniac ad sample (imgbb.com)
Sounds like a job for ScanTailor. I'm not aware of an actively developed alternative. The version on my system comes from ScanTailor Advanced [3].
[1]: https://scantailor.org/ [2]: https://github.com/scantailor/scantailor [3]: https://github.com/4lex4/scantailor-advanced
Neat idea. Basically an "Enhance Readability" button. I'm looking into how it can be done, will report back.