I decided to play around with this. I opened a PDF then captured part of it with grab, this is an easy way to crop parts and converts them to TIFF. I then opened the TIFF and saved it as a JPEG.
Try opening your PDF with preview or any photo program and load it tohttp://www.resizeimage.4u2ges.com/index.asp
Total disclosure: I've just started playing with this myself.
Digital Navy made the same point on their web site with similar pictures. That said, duplicating the effect in paper is going to look more like sloppy tecknique more than detailed modeling.