DeutschRitter

I have the following question: I need to scan my documents (e.g. credentials) for my job applications. I scanned my documents with a very good scanner, but some lines have different intensity of shade of grey and the lines have a different thickness (the lines are not shown correctly). I wanted to know if there is a plugin or an oportunity in paint.net to improve the quality of scanned documents (in black and white; not in colours).