แปลง PDF เป็น Image ใน Java

Presentation pres = new Presentation();
try {
    pres.getSlides().addFromPdf("InputPDF.pdf");
    Dimension size = new Dimension(960, 720);
    for (int index = 0; index < pres.getSlides().size(); index++)
    {
        ISlide slide = pres.getSlides().get_Item(index);
        BufferedImage bufferedImage = slide.getThumbnail(size);
        ImageIO.write(bufferedImage, "PNG", new File("image_java_" + index + ".png"));
    }
} finally {
    if (pres != null) pres.dispose();
}