How do I keep file sizes down when editing PDFs?
I have a set of white label PDF forms that I need to brand for our company. The initial document is 6 pages, 316KB, and already has a full set of fillable fields. In a perfect world, I just open up the first page, replace the header with a header that has our logo, save, and be on my merry way. If the file size jumps a bit, I can just go into Acrobat and "Reduce File Size."
However, the results were really bad. I think I about doubled the file size by doing this on one page alone. I thought the inflated size might have something to do with fonts since I had to "Find Fonts" in Illustrator, so I outlined my company's header (it used a different font) and went through every page to get all of the fonts on the same page. The results were worse: 2.49MB!
PDF file sizes have always felt like a dark art to me, and I want that to change. If my Photoshop file is huge, I know it's because of document dimensions, layers, and such. When my AI file sizes got out of control, I learned that unchecking "save PDF compatible version" would help out a lot. When I'm making my own PDFs and I want to export them, I have a solid grasp on downsampling and such to get a good file size.
But when it comes to editing PDFs, I really don't know how file sizes work. I don't know what "Reduce File Size" means. I don't know why sometimes a file size will double or triple and why it sometimes won't, and if PDFs are embedding duplicate data, I don't know how to get it out.
So, how do I keep file sizes down when editing PDFs?
Look around for the
Audit space usage ... option (explained here). In newer versions it is oddly hidden under
Save as >
Optimized PDF. That will tell you exactly where the bloat is coming from. You can also use the
Optimized PDF option to crank the size down in very targeted ways.
Given the big before/after shift, the culprit is probably the image you're embedding. Try exporting that file in various formats (PDF, jpg, png) and then import it.