Extract highlights from PDF documents automatically

To extract highlights from PDF documents automatically, you can use various tools or scripts that detect and extract annotations, especially highlighted text, from PDF files. Here’s a streamlined overview of how to do it:

1. Using Python with PyMuPDF (aka fitz)

python
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import fitz  # PyMuPDF

def extract_highlights(pdf_path):
    doc = fitz.open(pdf_path)
    highlights = []

    for page_num, page in enumerate(doc, start=1):
        for annot in page.annots() or []:
            if annot.type[0] == 8:  # Highlight annotation
                quad_points = annot.vertices
                words = page.get_text("words")
                for i in range(0, len(quad_points), 4):
                    rect = fitz.Quad(quad_points[i:i+4]).rect
                    for w in words:
                        word_rect = fitz.Rect(w[:4])
                        if rect.intersects(word_rect):
                            highlights.append({
                                "page": page_num,
                                "text": w[4]
                            })
    return highlights

# Example usage
highlights = extract_highlights("example.pdf")
for h in highlights:
    print(f"Page {h['page']}: {h['text']}")

2. Tools & Applications That Extract Highlights

• Adobe Acrobat Reader DC

  • Go to Comments pane and filter highlights.

  • Export comments/highlights as an FDF or text file.

• Zotero with Zotfile Plugin

  • Automatically extracts highlighted text when syncing PDFs from Zotero.

  • Outputs extracted highlights into the notes field.

• PDF Expert (Mac)

  • Allows exporting all highlights from PDFs as text.

• PDF XChange Editor (Windows)

  • Export comments (including highlights) via Comments > Export.

3. Online Services

Some web-based services allow uploading a PDF to extract highlights:

• www.pdfhighlights.com

• www.sumnotes.net

Ensure the content is not sensitive, as uploading to third-party services can have privacy implications.

4. Command Line with pdfannots (Python Script)

pdfannots is a script that extracts annotations from PDFs using pdfminer.

Install and use:

bash
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pip install pdfannots
pdfannots yourfile.pdf > highlights.txt

Conclusion

For automated and programmable highlight extraction, Python with PyMuPDF is the most flexible solution. For GUI-based workflows, tools like Adobe Acrobat, Zotero, or PDF XChange Editor are reliable and user-friendly.