Greetings Torsten. I use a transparent terminal over the PDF and then screenshot it!
This is, as you would expect, an ultralight and ultrafast solution. In fact, I use mupdf to open the PDF, then open the venerable SC spreadsheet calculator in a transparent terminal over it. Once ‘filled’, I just take a screenshot! Then use Imagemagick to convert it. But, you would get the idea that many other possibilities open this way ;) (I am not a programmer but an Intensive care specialist doctor in Australia. I am a heavy user of Linux, emacs and orgmode.) I sincerely hope this contribution as a non programmer helps you and others. Please do publish this in the mailing list if you think it is beneficial. Cheers, Balaji Dr. Balaji Bikshandi Sent from my iPhone