Commercial printers often welcome submissions in PDF format since these files contain all of the necessary font, graphic and layout information wrapped up in one, neat package. Failure to verify proper resolution of the embedded images before sending, however, may result in production issues -- for example, by providing the printer with unnecessarily excessive graphical data or, worse, not enough to ensure a high-quality output. Adobe Acrobat Professional's "Preflight" feature provides you with quick access to this resolution information.
Preflighting Your Document
With your PDF open in Acrobat Pro, click on the "Tools" menu and select "Print Production" followed by "Preflight." Click "Select Profile" and then choose the print profile suggested by your printer -- or, if you've not been provided with a suggestion, simply select "PDF/X Compliance." Click "Analyze" to run the inspection and generate the report, which includes resolution data for any embedded images.
Third Party Assistance
The free version of Adobe's Acrobat Reader does not feature a Preflight tool, so you'll have to resort to a third-party preflight app to get the job done. These solutions -- which include titles like PitStop Pro, pdfToolbox or FlightCheck -- will take a document that's already saved in PDF format and review its package for the appropriate resolution, colors, fonts and other printable elements.
Resolution Doesn't Always Matter
If your PDF contains only text and vector images -- in other words, graphics comprised of points, lines, shapes and curves instead of individual pixels , as in a photograph -- you need not even worry about resolution since these elements retain their crispness, regardless of file size and magnification.