We frequently need to mail pdf files that are too big for regular mail services, such as a 40MB pdf file with a maximum 10MB send restriction. In such situations quick and effective pdf compression comes in handy that does not reduce the quality to a level of the file becoming unusable.
GhostScript
Under Linux and Unix-like systems GhostScript is one of the most powerful tools (probably the most powerful one) to manipulate files like pdf, ps, etc. If you are on a Linux/Unix-like system and need a job with pdf files done check out the “How to use GhostScript” site. It’s not unlikely that GhostScript already has a built in solution to your problem. Consequently it also features a way of effectively compressing pdf files with different options and settings.
GhostScript pdf compression
Effective pdf compression is possible with GhostScript using a single command (adapted from here and here):
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -sOutputFile=outputfile.pdf inputfile.pdf
-dPDFSETTINGS= specifies the quality level of the pdf file. This effects embedded pixel graphics (also adapts embedded color profiles) and is the main option for controlling the compression level, thereby the resulting file size:
- -dPDFSETTINGS=/screen (72 dpi images)
- -dPDFSETTINGS=/ebook (150 dpi images)
- -dPDFSETTINGS=/printer (300 dpi images)
- -dPDFSETTINGS=/prepress (300 dpi images, color preserving)
- -dPDFSETTINGS=/default
Other switches: the output is written as pdf (-sDEVICE=pdfwrite), the pdf compatibility level is set to 1.4 (-dCompatibilityLevel=1.4), the process does not require user interaction (-dNOPAUSE and -dQUIET), and GhostScript skips the startup message (-dQUIET).