🚀 go-pugleaf

David,

When you print to PDF (or Distill in two steps), your transparency gets flattened BEFORE the PDF is made, so the transparency is not really there, just the "appearance" of the transparency. Exporting to PDF 1.4 (Acrobat 5) or later keeps the transparency "Live" in the PDF so that flattening can be handled in the RIP, as well as eliminating flattening artifacts (referred to as stitching, which appear as thin white lines along the borders of transparent regions in front of a colored background) during on-screen viewing.

Although Illustrator is not a general purpose PDF editing tool, it can be instructive to do a little demonstration of the difference in the structure of the same file exported and printed to PDF. Start by placing a photograph as a background, then use one of InDesign's shape tools to put a filled shape in front of the photo, and apply a drop shadow to the shape. Export and print using the Press Quality preset (which will keep the transparency live in the export, but the printed PDF will be flattened, despite its PDF 1.4 compatibility).

First, you'll probably see stitching in Acrobat on the printed version, and it may be lighter in appearance overall than the exported version. Now open the two version in Illustrator. Open the layers panel and keep expanding the groups until you are able to isolate the shape and drop shadow elements (in the exported version the shadow will probably be grouped with a clipping mask, while in the printed version the shadow may be in several pieces and has been burned into a copy of the background photo). Try to select the shape and shadow and move them relative to the background.

Mostly, though, I was referring to the fact that you can't use bookmarks, buttons, or other interactive elements in Printed PDF.