I spent several days trying to find a way to edit scanned and downloaded PDF documents. I looked at most of the applications mentioned in the recent thread, which is the easiest pdf tool.
In addition, I tried gocr, the open source Optical Character Recognition application, which warned that it was in development and did not work.
Along the way, I happened upon this link Make Gadgets Work !!!: How to edit PDF in Linux - The easy way. in an older OpenSUSE forum thread that I can’t find now. It caused me to look at Calibre more carefully.
It is billed as an e-book organizer and reader but the Calibre’s file conversion features are truly amazing.
By converting PDF to a .odt (Libre Office Writer) file, I can edit it any way I want and then convert it back to PDF or any one of the other formats. They do warn that PDF is a poor format to work with, but I had very few problem and the learning curve was not steep.
This opens all kinds of new possibilities in my mind. For example, I have copies of the owner manuals for my BlackBerry, FujiFilm Camera several other things on my Kindle in PDF format. The problem is that the PDF files do not scale and are too small to read when I need them. By converting them to an e-book format (like Mobi), they become easily readable and searchable on my Kindle or Blackberry.
Anyone who needs to work with PDF documents should take a second look at Calibre as a file converter instead of an e-book library/reader.