This sample code list the properties of all the images present in a PDF document such as image width, height, compression, color space, num components and bits per component:

PDFDocument pdfDoc = new PDFDocument ("c:/test20.pdf", null);
List<? extends IImageResource> imageList = pdfDoc.getResourceManager().listImages();
for (IImageResource image : imageList)
{
    System.out.println(image.getWidth() + " x " + image.getHeight());
    System.out.println(image.getCompression());
    System.out.println(image.getColorSpace());
    System.out.println(image.getNumComponents());
    System.out.println(image.getBitsPerComponent() + " bpc");
}