Finds differences between two PDF documents:
- Compares the text layers of two PDF documents and outputs the bounding boxes of changed text in JSON.
- Rasterizes the changed pages in the PDFs to a PNG and draws red outlines around changed text.
The script is written in Python 3, and it relies on the pdftotext program.
libxml2 >= 2.7.0, libxslt >= 1.1.23, poppler
sudo apt-get install python3-lxml poppler-utils
brew install libxml2 libxslt poppler
From PyPI:
pip install pdf-diff
From source:
sudo python3 setup.py install
Turn two PDFs into one large PNG image showing the differences:
pdf-diff before.pdf after.pdf > comparison_output.png
To deploy:
python3 -m pip install --user --upgrade setuptools wheel twine
python3 setup.py sdist bdist_wheel
python3 -m twine upload dist/*
compute_changes
│
├── serialize_pdf (called twice)
│ ├── pdf_to_bboxes
│ ├── mark_eol_hyphens
│ │ └── mark_eol_hyphen
│ └── Processes bounding boxes and text
│
├── perform_diff
│ └── Calls external `fast_diff_match_patch`
│
└── process_hunks
├── Iterates through diff hunks
└── mark_difference (called multiple times)
render_changes
│
├── simplify_changes
├── make_pages_images
│ └── pdftopng (converts PDF pages to images)
├── realign_pages
│ ├── Splits pages into sub-pages
│ └── Adjusts box coordinates
├── draw_red_boxes
│ └── Annotates images with rectangles or lines
└── zealous_crop
└── Crops the image to reduce unnecessary margins
stack_pages
│
└── Combines processed images into a final output