Convert Two Up Imposed PDF

A Python tool to process scanned 2-up imposed PDFs (signature scans) and produce upright, single-page PDFs in correct reading order.

This tool handles:

• Alternating 90° rotated scans (top of page on right/left alternates)
• 2-up page splitting (left/right halves of each scanned sheet)
• Signature reordering to restore natural reading order
• Optional compression and quality control for high-DPI scans

Features

• Fully automated for signature PDFs (number of pages must be a multiple of 4)
• Outputs a standard, upright PDF ready for printing or digital use
• Adjustable JPEG compression for smaller file sizes
• Cross-platform (requires Python 3.8+)

Installation

pip install convert-two-up-imposed-pdf

Usage

convert-two-up-imposed-pdf <input_pdf> <output_pdf> [--dpi DPI]

Arguments

Example

convert-two-up-imposed-pdf scanned_booklet.pdf output_booklet.pdf --dpi 200

• Detects the number of scanned sheets
• Computes total logical pages
• Applies alternating rotation correction
• Splits 2-up pages
• Reorders pages according to booklet imposition
• Saves the final upright PDF

Compression and Quality Tips

• By default, pages are saved as JPEG to reduce file size
• Adjust --dpi for higher or lower resolution
• You can tweak the JPEG quality in the code (default: 85) to balance file size and image fidelity
• Optional grayscale conversion and subsampling further reduce file size for text-heavy scans

Requirements

• Python 3.8+
• PyMuPDF
• Pillow

Limitations

• Total logical pages must be a multiple of 4
• Assumes strictly alternating rotation for scanned pages (top of page right/left)
• Works best for scanned image-based PDFs; vector PDFs may not behave as expected

License

Unlicense

Acknowledgements

Most code in this repository, including this README, was produced by the ChatGPT (OpenAI) LLM. Some tweaks and improvements were made by the human author. The human author reviewed and verified all output.

• Uses PyMuPDF for PDF processing
• Uses Pillow for image manipulation