PDF Compress Tool
Performs actual PDF compression, supporting both target size and percentage modes. Unlike existing solutions that only provide guidance, this tool compresses files directly.
Features
- Two compression modes: target size (
--target-size 2MB) / percentage (--reduce 30) - Three-stage compression pipeline: pikepdf structural optimization → Ghostscript progressive compression → QPDF secondary optimization
- Quality floor protection: three levels (high / medium / low) to prevent excessive compression from damaging image quality
- Batch processing: compress all PDFs in a directory at once
- Auto dependency detection: detects available tools at runtime and adapts compression strategy accordingly
Usage
Compress to target size
"Compress this PDF to under 2MB"
"Compress this PDF to under 5MB"
python compress_pdf.py report.pdf --target-size 2MB
Compress by percentage
"Reduce the file size by 30%"
"Reduce the file size by 50%"
python compress_pdf.py report.pdf --reduce 30
Specify output path and quality
python compress_pdf.py report.pdf --reduce 50 --quality low -o small.pdf
Batch processing
"Compress all PDFs in the papers folder to under 2MB"
python compress_pdf.py --batch ./papers --target-size 2MB
python compress_pdf.py --batch ./papers --reduce 40 --quality high
Compression Strategy
Stage 1: pikepdf structural optimization
Removes redundant objects, compresses streams, and packs object streams. Lossless operation that preserves maximum image quality.
Stage 2: Ghostscript progressive compression
Tries prepress → printer → ebook → screen progressively, checking at each level and stopping as soon as the target is met. Also supports custom DPI downsampling (100 → 72 → 50 → 36 dpi), subject to quality floor protection.
Stage 3: QPDF secondary optimization
Object stream generation and stream recompression, saving an additional 5-15%. Requires qpdf installation (optional).
Quality floor protection
| Level | Meaning | Minimum compression level | Use case |
|---|---|---|---|
high |
Quality priority | printer (300dpi) | Documents intended for printing |
medium |
Balanced (default) | ebook (150dpi) | Everyday use |
low |
Size priority | screen (72dpi) and below | Screen viewing only |
Dependencies
- python3 (required)
- ghostscript (recommended): core compression engine
- qpdf (optional): secondary structural optimization, additional 5-15% compression
- pikepdf (auto-installed via pip): Python PDF library, fallback when Ghostscript is unavailable
Install by platform
| Dependency | macOS | Linux (Debian/Ubuntu) | Linux (RHEL/Fedora) | Windows |
|---|---|---|---|---|
| ghostscript | brew install ghostscript |
sudo apt-get install ghostscript |
sudo dnf install ghostscript |
choco install ghostscript or download |
| qpdf | brew install qpdf |
sudo apt-get install qpdf |
sudo dnf install qpdf |
choco install qpdf or download |
| pikepdf | pip install pikepdf (auto) |
pip install pikepdf (auto) |
pip install pikepdf (auto) |
pip install pikepdf (auto) |
The script auto-detects your platform and shows the correct install command when a dependency is missing.