pdf-compressor

How to Compress PDF Files in Python

This directory contains two approaches:

• Legacy (commercial): pdf_compressor.py uses PDFTron/PDFNet. PDFNet now requires a license key and the old pip package is not freely available, so this may not work without a license.
• Recommended (open source): pdf_compressor_ghostscript.py uses Ghostscript to compress PDFs.

Ghostscript method (recommended)

Prerequisite: Install Ghostscript

• macOS (Homebrew):
  • brew install ghostscript
• Ubuntu/Debian:
  • sudo apt-get update && sudo apt-get install -y ghostscript
• Windows:
  • Download and install from https://ghostscript.com/releases/
  • Ensure gswin64c.exe (or gswin32c.exe) is in your PATH.

No Python packages are required for this method, only Ghostscript.

Usage

To compress bert-paper.pdf into bert-paper-min.pdf with default quality (power=2):

python pdf_compressor_ghostscript.py bert-paper.pdf bert-paper-min.pdf

Optional quality level [power] controls compression/quality tradeoff (maps to Ghostscript -dPDFSETTINGS):

• 0 = /screen (smallest, lowest quality)
• 1 = /ebook (good quality)
• 2 = /printer (high quality) [default]
• 3 = /prepress (very high quality)
• 4 = /default (Ghostscript default)

Example:

python pdf_compressor_ghostscript.py bert-paper.pdf bert-paper-min.pdf 1

In testing, bert-paper.pdf (~757 KB) compressed to ~407 KB with power=1.

Legacy PDFNet method (requires license)

If you have a valid license and the PDFNet SDK installed, you can use the original pdf_compressor.py script. Note that the previously referenced PDFNetPython3 pip package is not freely available and may not install via pip. Refer to the vendor's documentation for installation and licensing.