If your system has "The Gimp" software package, you can open a pdf with Gimp and save it as a tif. I just tried this under Ubuntu and it worked ok.
This may be irrelevant to your question. I don't know if Gimp can be run from the command line.
Last edited by flshope; 05-08-2013 at 12:02 PM.
Reason: Failed to read question fully. Sorry.