scantailor-universal VS OCRmyPDF

You could try ScanTailor: https://scantailor.org/

There's also https://scantailor.org/ (and a maintained fork at https://github.com/4lex4/scantailor-advanced ) which semi-automates unwarping and other corrective tasks in scanned books.

Scantailor (https://scantailor.org) is the tool for self-scanned books that exist in images (png, jpg, etc). However, I usually use Irfanview with PDF plugin (https://irfanview.com - download both Irfanview and the Plugins from this home page) I have elsewhere in r/PDF shown how you can do batch splitting of two-page scans, clean up muddy pages (yellowed or browned) . In the Reddit search box, search for Irfanview in this subreddit. Irfanview has lots of commands, so the instructions are very specific, and which I did trial and error on before posting. This is because Irfanview is an image processor and viewer, and PDF transformations are recent to the last couple of years. Note that you will want to run OCR after Irfanview processing, as Irfanview treats PDFs as images (which is what you have now).

Scantailor https://scantailor.org/ might be useful.

scantailor is a good open source option that has a lot of features centered towards this process.

I use OCRmyPDF on a regular basis to OCR journal articles my library sends me.

I've found it works great on English but (with appropriate language packs installed) works poorly on Greek and Hebrew. It also makes no effort to understand the layout of pages (e.g., tables).

The project is fantastic, though. I've often considered building a web frontend that cleans up PDFs and then OCRs them using OCRmyPDF.

For cleaning, check out https://scantailor.org/

Next is the cleanup. Scan Tailor is the best game in town for this, but it's a dead project. Instead, there are two forks that have picked up where the original developers left off. Scan Tailor Advanced is my current fork of choice, though Scan Tailor Universal tries to add new usability features. For whatever reason, only Advanced makes full use of my CPU, so it's several times faster than Universal for the time being.

As mentioned in the other replies, Google's OCR is limited. OCRmyPDF is designed for PDFs. So if you download a 1000+ page public-domain dictionary off of Archive.org (which is something I do regularly), and you want to re-run the OCR because Internet Archive doesn't tune its OCR very well for multilingual works (if it all), then OCRmyPDF is going to beat Google's automatic OCR every time.

However, I recently paid a programmer to fork OCRmyPDF to give it the option to use Google's OCR engine instead of Tesseract. That fork is here: https://github.com/ualiawan/OCRmyPDF. It's more fiddly than the regular OCRmyPDF, and it requires a Google Cloud Vision account (which charges some fraction of a cent for each page OCRed), but it works well, and in some cases may produce better results than OCRmyPDF, although you must be sure to specify the language of the document.