If you’re processing large PDF files, you may want to optimize the filesize. Here’s what I found to be working. These tools all require Ghostscript.
$ yum install ghostscript
$ apt-get install ghostscript
Convert the PDF to the “ebook” format. For a few tests, this took 65% of the original filesize (18MB to 6MB).
$ gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook \
-dNOPAUSE -dBATCH -dQUIET -sOutputFile=output.pdf input.pdf
If you want to try, you can also try the “screen” format. This reduced the test PDFs from 18MB to 1.5MB, so a very large reduction, but image quality inside the PDF was no longer up to the standards.
$ gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen \
-dNOPAUSE -dBATCH -dQUIET -sOutputFile=output.pdf input.pdf
I’ve read reports that using ghostscript to convert the PDF to GhostScript format and back to PDF can also substantially reduce the filesize. My tests did not confirm this, I ended up with files +15% larger. You’ll need to test this for your own needs.
$ pdf2ps original.pdf original.ps $ ps2pdf original.ps new.pdf
And when all else fails, just compress the file with zip (zip instead of gzip/tar, to help our Windows friends with opening the files more easily).
$ zip file.zip original.pdf
Should anyone else have more tips, I’d love to hear them!