private PDFXObject addRenderedImage(String key, RenderedImage img) {
ImageInfo info = new ImageInfo(null, "image/unknown");
ImageSize size = new ImageSize(img.getWidth(), img.getHeight(), 72);
info.setSize(size);
ImageRendered imgRend = new ImageRendered(info, img, null);
ImageRenderedAdapter adapter = new ImageRenderedAdapter(imgRend, key);
PDFXObject xObject = pdfDoc.addImage(resourceContext, adapter);
flushPDFDocument();
return xObject;
}