PDF Polygon Image Extractor

Description

This Python script provides a graphical user interface (GUI) to extract a custom polygonal area from every page of a PDF document. It is designed to be user-friendly, allowing you to visually select the region you want to crop.

The tool first displays a random page from the selected PDF. If the page is too large for your screen, it automatically resizes it to fit. You can then click to define the vertices of a polygon. The script intelligently translates these clicks back to the original, full-resolution coordinates.

After you close the selection window, the script processes every page of the PDF, cropping the exact polygonal area you defined and saving each one as a high-quality PNG image.

Features

• Interactive Polygon Selection: Draw any custom shape (not just a rectangle) to define the area you want to extract.
• GUI for Ease of Use: A simple point-and-click interface for selecting the PDF and the crop area.
• Handles Large PDFs: Automatically resizes the selection image to fit your screen, making it easy to work with high-resolution documents.
• Accurate Coordinate Scaling: Intelligently converts coordinates from the resized preview image to the full-resolution original, ensuring precision.
• Batch Processing: Applies the same polygonal crop to every single page of the PDF automatically.
• High-Quality Output: Extractions are performed on high-DPI renderings of the PDF pages to maintain quality. The output images are saved as PNGs with transparency.

Requirements

Before running the script, you need to have Python installed. The following Python libraries are also required:

• PyMuPDF: For reading and rendering PDF files.
• Pillow: For image manipulation (cropping, resizing).
• Tkinter: For the GUI. (This is usually included with standard Python installations on Windows and macOS).

You can install the necessary libraries using pip:

pip install PyMuPDF Pillow

How to Use

1. Save the Code: Save the script as a Python file (e.g., pdf_extractor.py).

2. Run the Script: Open a terminal or command prompt, navigate to the directory where you saved the file, and execute it:

   python pdf_extractor.py

3. Select a PDF: A file dialog will pop up. Choose the PDF file you wish to process.

4. Define the Polygon:

   • A new window will appear, showing a random page from your PDF.
   • Click on the image to place the corners (vertices) of the polygon you want to extract.
   • Red dots and lines will appear to give you visual feedback on your selection.
   • You need to select at least 3 points to form a valid polygon.

5. Confirm Selection: Once you are satisfied with your selection, simply close the image window.

6. Processing: The script will begin processing in the background. You will see progress updates in the terminal.

Output

The script will create a new folder named extracted_images in the same directory where the script is located.

Inside this folder, you will find the cropped images, named sequentially:

• page_1_polygon_crop.png
• page_2_polygon_crop.png
• ...and so on for every page in the PDF.

The output images are PNG files with a transparent background, containing only the polygonal area you selected.

Configuration

You can adjust the quality of the output images by changing the PROCESSING_DPI variable at the bottom of the script:

if __name__ == "__main__":
    # ...
    # Higher DPI gives better quality output, but uses more memory.
    # This value must be consistent between selection and extraction.
    PROCESSING_DPI = 200 # <-- Change this value if needed
    # ...

• A higher DPI (e.g., 300) will result in larger, higher-quality images but will use more memory and take longer to process.
• A lower DPI (e.g., 150) will be faster but produce smaller, lower-quality images.

The default value of 200 provides a good balance between quality and performance.