pdf-recompression.md

Recompressing PDFs with GhostScript

Like EPUBs, PDFs are often larger than they need to be

Often, large PDFs can be cut down to size with the following:

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -sOutputFile=output.pdf input.pdf

In my experience, rarely, but not never, if the output is of undesirably low quality, -dPDFSETTINGS=/printer can be used instead to get acceptable quality and still have smaller file size.

Sometimes, even further reductions can be gained by converting the PDF to a DJVU like so:

pdf2djvu output.pdf > output.djvu

Alternatively, the PDF can be XZ-compressed for further savings.