PDF Toc Bookmarks

PDF TOC to Bookmarks

Extract table of contents from PDF pages and create clickable bookmarks using visual analysis and PyMuPDF.

When to Use This Skill

Use this skill when:

• User wants to add bookmarks to a PDF that lacks them
• PDF has printed TOC pages but no clickable navigation
• User mentions "bookmarks," "navigation," "TOC," or "table of contents" for PDFs

Workflow

1. Extract TOC Pages as Images

Extract TOC pages at high resolution for visual analysis:

from scripts.extract_toc_images import extract_toc_images

extract_toc_images(
    pdf_path="/path/to/file.pdf",
    toc_start_page=10,  # First TOC page (1-based)
    toc_end_page=16,    # Last TOC page (1-based)
    output_dir="/mnt/user-data/outputs/toc_images"
)

2. Analyze Images Visually

Use Claude's vision capabilities to read TOC structure from images:

from view import view

# View each TOC image
view("/mnt/user-data/outputs/toc_images/page_010.png")
view("/mnt/user-data/outputs/toc_images/page_011.png")
# ... view all TOC pages

Manually transcribe TOC structure into Python list format:

toc = [
    [1, "Chapter 1: Introduction", 10],
    [2, "1.1 Overview", 11],
    [3, "1.1.1 Background", 12],
    [2, "1.2 Methods", 15],
    [1, "Chapter 2: Results", 20],
]

Format: [level, title, printed_page_number]

• level: Hierarchy depth (1=chapter, 2=section, 3=subsection)
• title: Exact text from TOC
• printed_page_number: Page number as printed in book (not PDF page index)

3. Determine Page Offset

Calculate offset between printed page numbers and PDF page indices:

import fitz

doc = fitz.open("/path/to/file.pdf")

# Find a known page (e.g., where Chapter 1 starts)
# If book says "page 13" but it's PDF page 17, offset = 4
offset = actual_pdf_page - printed_page_number

Common offsets: 0-10 pages (cover, copyright, preface typically not numbered)

4. Add Bookmarks to PDF

from scripts.add_bookmarks import add_bookmarks

add_bookmarks(
    pdf_path="/path/to/input.pdf",
    toc_list=toc,
    page_offset=4,  # Offset calculated above
    output_path="/mnt/user-data/outputs/file_with_bookmarks.pdf"
)

5. Verify and Deliver

Open output PDF in viewer to confirm bookmarks navigate correctly. Provide download link to user.

Critical Insights

Vision > Text Parsing: OCR/regex for TOC extraction is unreliable due to formatting variations. Visual analysis by Claude is faster and more accurate.

Page Offset: Always verify offset. Test by clicking a bookmark and checking if it lands on correct page.

Hierarchy Levels: Maintain consistent level numbering (1=chapter, 2=section, 3=subsection) for proper nesting in PDF viewer.

PyMuPDF Reference

import fitz

# Open PDF
doc = fitz.open("file.pdf")

# Extract page as image
page = doc[page_index]  # 0-based
mat = fitz.Matrix(2.0, 2.0)  # 2x zoom
pix = page.get_pixmap(matrix=mat)
pix.save("output.png")

# Set TOC (bookmarks)
toc = [
    [1, "Chapter 1", 10],  # level, title, page (1-based)
    [2, "Section 1.1", 11],
]
doc.set_toc(toc)

# Save PDF
doc.save("output.pdf")
doc.close()

Example Session

User: "Add bookmarks to this PDF based on the table of contents"

1. Extract TOC pages (10-16) as images
2. View images and transcribe TOC structure
3. Calculate page offset (e.g., 4 pages)
4. Create toc list with 182 entries
5. Add bookmarks using add_bookmarks script
6. Provide download link

Result: PDF with hierarchical bookmarks matching printed TOC

Time Savings

• Traditional (regex/OCR): 30-60 min with errors
• Vision-based (this skill): 10-15 min with high accuracy