I am have a bit of a problem converting some color PDFs to tiff images. The PDFs I am having problems with have hand written signatures written in blue ink. These signatures do not appear in the generated binary tiffs. I suspect there is a threshold value somewhere to determine which pixels will be black and which will be white.

```
@SuppressWarnings("serial")
private static void convertPdfToTiff(final File pdf, final File tif) throws Exception {
    try 
    {
        final Iterator<ImageWriter> imageWriterIterator = ImageIO.getImageWritersByFormatName("TIF");
        final ImageWriter imageWriter = imageWriterIterator.hasNext() ? imageWriterIterator.next() : null;

        final TIFFImageWriteParam writeParam = new TIFFImageWriteParam(Locale.getDefault());
        writeParam.setCompressionMode(TIFFImageWriteParam.MODE_EXPLICIT);
        writeParam.setCompressionType("LZW");

        PDDocument pdfDocument = PDDocument.load(pdf);
        PDFRenderer pdfRenderer = new PDFRenderer(pdfDocument);

        OutputStream out = new FileOutputStream(tif);
        final BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(out);
        final ImageOutputStream imageOutputStream = ImageIO.createImageOutputStream(bufferedOutputStream);
        imageWriter.setOutput(imageOutputStream);
        imageWriter.prepareWriteSequence(null);

        int pageCounter = 0;
        for (PDPage page : pdfDocument.getPages()) 
        {
            BufferedImage image = pdfRenderer.renderImageWithDPI(pageCounter, 300, ImageType.BINARY);

            final IIOImage s = new IIOImage(image, null, new TIFFImageMetadata(new TIFFIFD(new Vector<BaselineTIFFTagSet>() 
            {
                {
                       add(BaselineTIFFTagSet.getInstance());
                }
            }))) 

            {   
                {
                       final TIFFImageMetadata tiffMetadata = (TIFFImageMetadata) getMetadata();
                       final TIFFIFD rootIFD = tiffMetadata.getRootIFD();
                       final BaselineTIFFTagSet base = BaselineTIFFTagSet.getInstance();
                       rootIFD.addTIFFField(new TIFFField(base.getTag(BaselineTIFFTagSet.TAG_X_RESOLUTION), TIFFTag.TIFF_RATIONAL, 1, new long[][] { { 300, 1 } }));
                       rootIFD.addTIFFField(new TIFFField(base.getTag(BaselineTIFFTagSet.TAG_Y_RESOLUTION), TIFFTag.TIFF_RATIONAL, 1, new long[][] { { 300, 1 } }));
                }
            };

            imageWriter.writeToSequence(s, writeParam);
            pageCounter++;
        }

        imageWriter.dispose();
        imageOutputStream.flush();
        imageOutputStream.close();
        bufferedOutputStream.flush();
        bufferedOutputStream.close();
        pdfDocument.close();
        out.flush();
        out.close();
    } 
    catch (Exception e) 
    {
        e.printStackTrace();
        throw e;
    }
}

```