I did OCR professionally for a big contract here, and later for myself. So I know the basics.
Tesseract is it in Open source. Unless your disks are tiny, install debian 12 even on a usb disk, for tesseract. Use a minimum of 400DPI.; GOCR was miles behind performance-wise. There is this Commercial thing, Abbyy OCR which was used under M$ windows, and that's better again. Abbyy did a linux version and had a one month free trial on it. It's a kludgy install but good OCR.
I rescued the single surviving copy of my Dad's 2nd play that was typed up on a typewriter with the ribbon totally shot, and had handwritten edits in fountain pen with Abbyy, but tesseract wasn't far behind. The handwriting is always totally illegible to these scanners. It's good to pass these things through a word processor, so I resist scan2pdf, etc. Don't ignore the capabilities of a mobile phone either!
/Tangent:
What I'd really like to see is AI figuring some of this muddle out - deciphering unreadable writing, the Enigma codes, or other puzzles. Thet really tests the 'I' part of AI
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