This one’s been bugging me for several weeks so finally got around to finding a proper solution. Basically, if someone sends you a PDF file with some photos in it, the chances are they didn’t think of reducing the picture quality (in the original document) before creating the PDF. As a result, the PDF file can end up being enormous, for no obvious reason to the reader.
While I managed to find out how to tackle the problem from inside the likes of Microsoft Word (better options in Office 2011), I am often without the original document, so what to do there (on a Mac)?
Well, as it happens, Mac Preview does have a way of doing this which I found out about here, and while it worked well for me (PDF files were mostly text with 2-3 pictures anyway), I have seen comments on the above article questioning the quality of the resulting file. Still, it may work for you too.