Our application scans documents to PDF using Twain drivers. The document size has been good. Now we are forced to move to WIA drivers and I am having problems getting the documents to a similar size. The WIA documents are at a minimum at least twice as large. Can you suggest the optimum settings for the WIA driver to get to PDF?
It really comes down to your desired DPI. For instance, if you are outputting your PDF as A4 with a DPI of 144 (200% of the standard PDF DPI) then you need scan at no more than 1190 x 1684 (i.e. 595 x 2 and 842 x 2).
But you really need to do some tests to see what DPI gives you the optimal results.