12. The printer of claim 8 , wherein the first interpreter is Adobe PDF Print Engine (APPE) and the second interpreter is a Postscript interpreter, wherein step (a) includes detecting a version of the PDF by checking the document header without analyzing a content of the document; and wherein step (b) includes: (b1) if the version of the PDF document determined in step (a) is one of a pre-defined plurality of PDF versions, selecting only the APPE interpreter to be used to interpret the PDF document without analyzing the content of the document; and (b2) if the version of the PDF document determined in step (a) is not one of the pre-defined plurality of PDF versions, performing steps (b3) to (b5) for each page of the PDF document: (b3) determining whether the page contains transparency data; (b4) if the page contains transparency data, selecting the APPE interpreter to be used to interpret the page; and (b5) if the page contains no transparency data, selecting either the APPE interpreter or the second interpreter to be used to interpret the page.
14. The printer of claim 12 , wherein the selection in step (b5) is based on a busy or error status of the first and second interpreters.