PDFBOX change text colours and remove background

Hi, I want to make an apllication using pdfbox that changes all the text colour to black and removes backgrounds so pdfs can be printed saving ink.

Unfortunatelly I haven´t found any good place to read how to use pdfbox, I've found the api but that doesn't seem to be very descriptive and the examples only helped me to find out how to browse all the pages of a pdf and with any luck save changes.

Can anybody help me out?
I'd like to know how to change colour for all the text and how to remove backgrounds (I think they are called background paths) and maybe background images.

Thanks

Hey, i got the same problem, i tried to parse the pdffile to get only the Textcontent but if i try this i'll get a Nullpointer...
For me it would be okay if i just can set the background to white, then i can choose black and white printing so it would save ink too.


Here you can see how i tried it and thats where the Nullpointer occured.

Code:

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for(File pdf : pdfFiles)
    {
      PDFParser parser = new PDFParser(new FileInputStream(pdf));
      parser.parse();
      PDDocument doc = parser.getPDDocument();
      pddoc.add(doc);
      PDFTextStripper stripper = new PDFTextStripper();
      String textContent = stripper.getText(doc);
      doc.close();
    }

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