So i have an object which holds an attachment. this object is pretty much an invoice and has the option to be turned into a pdf document for printing purposes. the invoice will hold an image as an attachment within itself. now i need to figure out how to make the image show up on the pdf? the pdf is a visual force page with renderAs="pdf" on it i need to kno how to reference the attachment of any invoice object when i click the "Print PDF" button on any individual invoice.