private void writeImage(PDDocument document, String imageFormat, String outputPrefix,
int imageType, float dpi) throws IOException
{
List pages = document.getDocumentCatalog().getAllPages();
PDPage page = (PDPage) pages.get(0);
BufferedImage image = page.convertToImage(imageType, Math.round(dpi));
String fileName = outputPrefix + "1." + imageFormat;
System.out.println("Writing: " + fileName);
boolean res = ImageIOUtil.writeImage(image, fileName, Math.round(dpi));
assertTrue("ImageIOUtil.writeImage() failed for file " + fileName, res);
if ("jpg".equals(imageFormat) || "gif".equals(imageFormat))