Convert from PDF to JPEG, GIF, and/or PNG

I have a document that is in PDF and I would like to select portions of it (the graphics mainly) and convert to JPG, GIF, and PNG.  What is the best way to do this? 

Presently I am converting the document to bitmap and then editting it by selecting the pieces I want and pasting them back into the workspace and then using "save bitmap as".

 There must be another, more efficient way.  Isn't there?