📄 ShrinkPDF

A Streamlit web app to sanitize and compress PDF files. It remove locks, signatures, metadata, and embedded JavaScript, then shrink file size by recompressing all images and streams.

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Features

• Sanitize: strips everything that prevents clean editing or saving:

  • Usage-rights locks (/Perms, UR3)
  • Digital signatures and signature flags
  • XFA (LiveCycle dynamic form definitions)
  • Embedded JavaScript
  • Authoring metadata (/Info, /Metadata)
  • Pushbutton action fields (print/clear buttons)
  • RichText flags on text fields

• Shrink: reduces file size without changing the visual layout:

  • Recompresses all PDF streams with flate (zlib)
  • Converts all embedded images to RGB JPEG
  • Downsamples images above a target DPI cap
  • Applies chroma subsampling (4:1:1) at higher compression levels
  • Finds images everywhere they can hide: page resources, nested Form XObjects, Pattern resources, and soft-mask (/SMask) references

• Remove images: replaces all embedded images with 1×1 white placeholders, keeping the page layout intact

• Linearize output: optimizes the file for fast web viewing and archival (PDF/A-compatible)

• 5 compression presets:

  Level	JPEG quality	Max DPI	Chroma subsampling
  1	85	150	4:4:4 (full)
  2	60	120	4:4:4 (full)
  3	35	96	4:1:1 (aggressive)
  4	15	72	4:1:1 (aggressive)
  5	5	60	4:1:1 (aggressive)

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Requirements

• Python 3.11+
• See requirements.txt for full pinned dependencies

Core dependencies:

streamlit
pikepdf
Pillow

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Installation

git clone https://github.com/dennisheitmann/shrinkpdf.git
cd shrinkpdf

python -m venv venv
source venv/bin/activate        # Windows: venv\Scripts\activate

pip install -r requirements.txt

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Usage

streamlit run app.py

Then open http://localhost:8501 in your browser.

1. Upload a PDF
2. Select the operations to apply (sanitize / shrink / remove images)
3. Optionally keep metadata, convert to grayscale, or linearize the output
4. If shrinking, choose a compression level (1–5)
5. Click Process PDF
6. Download the result

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Project structure

shrinkpdf/
├── app.py             # Streamlit UI
├── pdf_helpers.py     # Core PDF processing logic
└── requirements.txt

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Notes

• Operations are applied in order: sanitize → remove images → shrink
• Remove images and shrink are mutually exclusive: if remove images is selected, shrink is skipped
• Grayscale conversion and linearization are also skipped when remove images is selected
• If only linearization is requested (no shrink or remove images), the file is re-saved with linearization only
• Images are decoded to RGB before recompression, handling RGB, CMYK, grayscale, and palette color spaces
• Images smaller than 50×50 px are skipped during shrink
• The page layout is never modified, only image data and stream compression are changed

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License

MIT