PDFBox: Remove text behind image

Question

I am in a requirement to split a pdf into two, one with image and one with text. I dont want to remove the text which are behind an image and it should be the part of the image pdf. I want to extract only the top layered text in the PDF. Can any one help on this?

I already extracted the image and text into two pdfs by looping through pdf operators. I am facing trouble when not to remove the text behind the PDF.

Answer 1

Code for removing text:

PDDocument document = null;
    try {
        document = PDDocument.load(new File(inputfilePath), password);
        PDPageTree allPages = document.getDocumentCatalog().getPages();
        for (int i = 0; i < allPages.getCount(); i++) {
            PDPage page = (PDPage) allPages.get(i);
            PDFStreamParser parser = new PDFStreamParser(page);

            parser.parse();
            List tokens = parser.getTokens();
            List newTokens = new ArrayList();
            for (int j = 0; j < tokens.size(); j++) {
                Object token = tokens.get(j);
                if (token instanceof Operator) {
                    Operator op = (Operator) token;

                    if (op.getName().equalsIgnoreCase(
                            "tj")) {
                        try {
                            // remove the one argument to this operator
                            newTokens.remove(newTokens.size() - 1);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        continue;
                    }
                    // Header doesn't contain versioninfo

                }
                newTokens.add(token);

            }
            PDStream newContents = new PDStream(document);
            ContentStreamWriter writer = new ContentStreamWriter(newContents.createOutputStream());
            writer.writeTokens(newTokens);
            // In writeTokens method, I closed the output stream.. This is
            // for future reference.. or it will throw stream not closed
            // error
            newContents.addCompression();
            page.setContents(newContents);
            if (DEBUG)
                System.out.println("Background image pdf creation process");
            document.setAllSecurityToBeRemoved(true);
            document.save(outputFolder + "/img_" + fileName);

And for removing the images and shades, I used the below code:

for (int j = 0; j < tokens.size(); j++) {
                Object token = tokens.get(j);
                if (token instanceof Operator) {
                    Operator op = (Operator) token;

                    // Text Extraction removing image and shades
                    if (op.getName().equalsIgnoreCase("do") || op.getName().equalsIgnoreCase("sh")

                            || op.getName().equalsIgnoreCase("gs") || op.getName().equalsIgnoreCase("bi")
                            || op.getName().equalsIgnoreCase("id") || op.getName().equalsIgnoreCase("ei")
                            || op.getName().equalsIgnoreCase("bmc") || op.getName().equalsIgnoreCase("bdc")
                            || op.getName().equalsIgnoreCase("emc") || op.getName().equalsIgnoreCase("m")
                            || op.getName().equalsIgnoreCase("w")
                            || op.getName().equalsIgnoreCase("re")

                    ) {
                        // remove the one argument to this operator
                        newTokens.remove(newTokens.size() - 1);
                        continue;
                    }
                }
                newTokens.add(token);

            }