pdf

PDF Processing Guide

Python Environment — MANDATORY

All Python scripts in this skill MUST run inside a virtual environment. No exceptions.

# Create venv (once per session, skip if .venv already exists)
python -m venv .venv

# Activate (Windows PowerShell)
.venv\Scripts\Activate.ps1

# Activate (bash/macOS)
source .venv/bin/activate

# Install dependencies INSIDE venv only
pip install pypdf pdfplumber reportlab

# For OCR (only if needed)
pip install pytesseract pdf2image

# For advanced rendering (only if needed)
pip install pypdfium2

Rules:

• NEVER run pip install globally — always activate .venv first
• Check if .venv exists before creating: Test-Path .venv
• All python scripts/... commands assume the venv is active
• Clean up .venv when the session is done if it was created for this task

Temp file cleanup — MANDATORY:

• All temp scripts MUST use .tmp_ prefix (e.g., .tmp_merge_pdfs.py)
• After the task completes, delete ALL .tmp_* files autonomously — never leave them behind, never ask the user
• Remove-Item is deny-listed in auto-approval mode. Use Python instead:

  .venv\Scripts\python.exe -c "import os,glob; [os.remove(f) for f in glob.glob('.tmp_*')]"
  

• If no .venv exists, use system python -c "..."

---

Overview

This guide covers PDF processing using Python libraries and command-line tools. For advanced features and JavaScript libraries, see reference.md. For PDF form filling, see forms.md.

Output directory: Save generated/merged/split .pdf files to the Obsidian vault (see shared-patterns.instructions.md § Artifact Output Directory). Create directories before writing. Never save into a git repo.

Note: scripts/ paths are relative to this skill folder (.github/skills/pdf/).

Quick Reference

Task	Best Tool	Key Code
Read/extract text	pdfplumber	page.extract_text()
Extract tables	pdfplumber	page.extract_tables()
Merge PDFs	pypdf	writer.add_page(page)
Split PDFs	pypdf	One page per file
Create PDFs	reportlab	Canvas or Platypus
Rotate pages	pypdf	page.rotate(90)
Add watermark	pypdf	page.merge_page(watermark)
Encrypt/decrypt	pypdf	writer.encrypt()
OCR scanned PDFs	pytesseract	Convert to image first
Fill PDF forms	See forms.md	Fillable or annotation-based
Command-line merge	qpdf	qpdf --empty --pages ...

---

Reading & Extracting

Quick Start

from pypdf import PdfReader

reader = PdfReader("document.pdf")
print(f"Pages: {len(reader.pages)}")

text = ""
for page in reader.pages:
    text += page.extract_text()

Text with Layout (pdfplumber)

import pdfplumber

with pdfplumber.open("document.pdf") as pdf:
    for page in pdf.pages:
        text = page.extract_text()
        print(text)

Extract Tables

import pdfplumber

with pdfplumber.open("document.pdf") as pdf:
    for i, page in enumerate(pdf.pages):
        tables = page.extract_tables()
        for j, table in enumerate(tables):
            print(f"Table {j+1} on page {i+1}:")
            for row in table:
                print(row)

Tables to Excel

import pdfplumber
import pandas as pd

with pdfplumber.open("document.pdf") as pdf:
    all_tables = []
    for page in pdf.pages:
        tables = page.extract_tables()
        for table in tables:
            if table:
                df = pd.DataFrame(table[1:], columns=table[0])
                all_tables.append(df)

if all_tables:
    combined_df = pd.concat(all_tables, ignore_index=True)
    combined_df.to_excel("extracted_tables.xlsx", index=False)

Extract Metadata

reader = PdfReader("document.pdf")
meta = reader.metadata
print(f"Title: {meta.title}, Author: {meta.author}, Pages: {len(reader.pages)}")

---

Merging & Splitting

Merge PDFs

from pypdf import PdfWriter, PdfReader

writer = PdfWriter()
for pdf_file in ["doc1.pdf", "doc2.pdf", "doc3.pdf"]:
    reader = PdfReader(pdf_file)
    for page in reader.pages:
        writer.add_page(page)

with open("merged.pdf", "wb") as output:
    writer.write(output)

Split PDF

from pypdf import PdfReader, PdfWriter

reader = PdfReader("input.pdf")
for i, page in enumerate(reader.pages):
    writer = PdfWriter()
    writer.add_page(page)
    with open(f"page_{i+1}.pdf", "wb") as output:
        writer.write(output)

---

Page Manipulation

Rotate Pages

from pypdf import PdfReader, PdfWriter

reader = PdfReader("input.pdf")
writer = PdfWriter()
page = reader.pages[0]
page.rotate(90)  # 90 degrees clockwise
writer.add_page(page)

with open("rotated.pdf", "wb") as output:
    writer.write(output)

Add Watermark

from pypdf import PdfReader, PdfWriter

watermark = PdfReader("watermark.pdf").pages[0]
reader = PdfReader("document.pdf")
writer = PdfWriter()

for page in reader.pages:
    page.merge_page(watermark)
    writer.add_page(page)

with open("watermarked.pdf", "wb") as output:
    writer.write(output)

---

Creating PDFs (reportlab)

Basic PDF

from reportlab.lib.pagesizes import letter
from reportlab.pdfgen import canvas

c = canvas.Canvas("hello.pdf", pagesize=letter)
width, height = letter
c.drawString(100, height - 100, "Hello World!")
c.line(100, height - 140, 400, height - 140)
c.save()

Multi-Page Report

from reportlab.lib.pagesizes import letter
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, PageBreak
from reportlab.lib.styles import getSampleStyleSheet

doc = SimpleDocTemplate("report.pdf", pagesize=letter)
styles = getSampleStyleSheet()
story = []

story.append(Paragraph("Report Title", styles['Title']))
story.append(Spacer(1, 12))
story.append(Paragraph("Body content here. " * 20, styles['Normal']))
story.append(PageBreak())
story.append(Paragraph("Page 2", styles['Heading1']))

doc.build(story)

Subscripts and Superscripts

IMPORTANT: Never use Unicode subscript/superscript characters in ReportLab. They render as black boxes. Use XML markup instead:

from reportlab.platypus import Paragraph
from reportlab.lib.styles import getSampleStyleSheet
styles = getSampleStyleSheet()

chemical = Paragraph("H<sub>2</sub>O", styles['Normal'])
squared = Paragraph("x<super>2</super>", styles['Normal'])

---

Security

Encrypt PDF

from pypdf import PdfReader, PdfWriter

reader = PdfReader("input.pdf")
writer = PdfWriter()
for page in reader.pages:
    writer.add_page(page)

writer.encrypt("userpassword", "ownerpassword")
with open("encrypted.pdf", "wb") as output:
    writer.write(output)

---

OCR (Scanned PDFs)

# Requires: pip install pytesseract pdf2image
# Also requires Tesseract OCR engine installed on system
import pytesseract
from pdf2image import convert_from_path

images = convert_from_path('scanned.pdf')
text = ""
for i, image in enumerate(images):
    text += f"Page {i+1}:\n"
    text += pytesseract.image_to_string(image)
    text += "\n\n"

---

Extract Images

# Using pdfimages (poppler-utils)
pdfimages -j input.pdf output_prefix
# Extracts as output_prefix-000.jpg, output_prefix-001.jpg, etc.

---

Command-Line Tools

qpdf

qpdf --empty --pages file1.pdf file2.pdf -- merged.pdf     # Merge
qpdf input.pdf --pages . 1-5 -- pages1-5.pdf               # Extract pages
qpdf input.pdf output.pdf --rotate=+90:1                    # Rotate page 1
qpdf --password=mypassword --decrypt encrypted.pdf out.pdf  # Decrypt

pdftotext (poppler-utils)

pdftotext input.pdf output.txt            # Extract text
pdftotext -layout input.pdf output.txt    # Preserve layout
pdftotext -f 1 -l 5 input.pdf output.txt # Pages 1-5 only

---

PDF Form Filling

For form filling workflows, read forms.md — it covers both fillable (AcroForm) and non-fillable (annotation-based) approaches with helper scripts.

---

Next Steps

• reference.md — Advanced pypdfium2, pdf-lib (JS), pdfjs-dist
• forms.md — Complete form filling workflow with validation