There is no copyright on scans.

Scanning is not transformative and does not result in a derivative work which can is protected by copyright law.

https://en.wikipedia.org/wiki/Wikipedia:Scanning_an_image_do...

https://law.stackexchange.com/questions/1214/who-owns-a-copy... points us to read the Compendium of US Copyright Office Practices at https://www.copyright.gov/comp3/docs/compendium.pdf

> 313.4(A) Mere Copies

> A work that is a mere copy of another work of authorship is not copyrightable. The Office cannot register a work that has been merely copied from another work of authorship without any additional original authorship. See L. Batlin & Son, 536 F.2d at 490 (“one who has slavishly or mechanically copied from others may not claim to be an author”); Bridgeman Art Library, Ltd. v. Corel Corp., 36 F. Supp. 2d 191, 195 (S.D.N.Y. 1999) (“exact photographic copies of public domain works of art would not be copyrightable under United States law because they are not original”).

A pdf file can contain more than just the raw images of the pages.

Certainly! If you add my latest Kirk/Spock slash fanfic to the end of the text, then that is transformative, so the resulting PDF is covered under copyright.

But you wrote "scan". Adding an OCR'ed text layer, or doing manual proofreading and layout ("sweat of the brow") is not sufficiently transformative to have copyright protection.

And we were specifically talking about scans of old books stored in shadow libraries.