PDF Processing Guide

Overview

This guide covers essential PDF processing operations using Python libraries and command-line tools. For advanced features, JavaScript libraries, and detailed examples, see reference.md. If you need to fill out a PDF form, read forms.md and follow its instructions.

Quick Start

from pypdf import PdfReader, PdfWriter

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

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

Python Libraries

pypdf - Basic Operations

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

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)

Extract Metadata

reader = PdfReader("document.pdf")
meta = reader.metadata
print(f"Title: {meta.title}")
print(f"Author: {meta.author}")
print(f"Subject: {meta.subject}")
print(f"Creator: {meta.creator}")

Rotate Pages

reader = PdfReader("input.pdf")
writer = PdfWriter()

page = reader.pages[0]
page.rotate(90)  # Rotate 90 degrees clockwise
writer.add_page(page)

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

pdfplumber - Text and Table Extraction

Extract Text with Layout

import pdfplumber

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

Extract Tables

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)

Advanced Table Extraction

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:  # Check if table is not empty
                df = pd.DataFrame(table[1:], columns=table[0])
                all_tables.append(df)

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

reportlab - Create PDFs

Basic PDF Creation

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

c = canvas.Canvas("hello.pdf", pagesize=letter)
width, height = letter

# Add text
c.drawString(100, height - 100, "Hello World!")
c.drawString(100, height - 120, "This is a PDF created with reportlab")

# Add a line
c.line(100, height - 140, 400, height - 140)

# Save
c.save()

Create PDF with Multiple Pages

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 = []

# Add content
title = Paragraph("Report Title", styles['Title'])
story.append(title)
story.append(Spacer(1, 12))

body = Paragraph("This is the body of the report. " * 20, styles['Normal'])
story.append(body)
story.append(PageBreak())

# Page 2
story.append(Paragraph("Page 2", styles['Heading1']))
story.append(Paragraph("Content for page 2", styles['Normal']))

# Build PDF
doc.build(story)

Command-Line Tools

pdftotext (poppler-utils)

# Extract text
pdftotext input.pdf output.txt

# Extract text preserving layout
pdftotext -layout input.pdf output.txt

# Extract specific pages
pdftotext -f 1 -l 5 input.pdf output.txt  # Pages 1-5

qpdf

# Merge PDFs
qpdf --empty --pages file1.pdf file2.pdf -- merged.pdf

# Split pages
qpdf input.pdf --pages . 1-5 -- pages1-5.pdf
qpdf input.pdf --pages . 6-10 -- pages6-10.pdf

# Rotate pages
qpdf input.pdf output.pdf --rotate=+90:1  # Rotate page 1 by 90 degrees

# Remove password
qpdf --password=mypassword --decrypt encrypted.pdf decrypted.pdf

pdftk (if available)

# Merge
pdftk file1.pdf file2.pdf cat output merged.pdf

# Split
pdftk input.pdf burst

# Rotate
pdftk input.pdf rotate 1east output rotated.pdf

Common Tasks

Image to PDF (Without Compression / High Quality)

# Method 1: Using PIL + pypdf (保持原画质)
from PIL import Image
from pypdf import PdfWriter
import io

# Create PDF from image without compression
images = ["photo1.jpg", "photo2.png"]  # Support jpg, png, etc.
writer = PdfWriter()

for img_path in images:
    # Open image
    img = Image.open(img_path)
    
    # Convert to RGB if necessary (for PNG with transparency)
    if img.mode in ('RGBA', 'P'):
        img = img.convert('RGB')
    
    # Save as temporary JPEG of original quality
    img_buffer = io.BytesIO()
    img.save(img_buffer, format='JPEG', quality=100, optimize=False)
    img_buffer.seek(0)
    
    # Create a blank PDF page matching image size
    page = writer.add_blank_page(
        width=img.width, 
        height=img.height
    )

# Method 2: Using reportlab (Recommended - Best Quality)
from reportlab.lib.pagesizes import letter
from reportlab.platypus import Image as RLImage, SimpleDocTemplate
from reportlab.pdfgen import canvas
import os

def images_to_pdf(image_paths, output_pdf, quality=100):
    """
    Convert images to PDF without quality loss
    
    Args:
        image_paths: List of image file paths
        output_pdf: Output PDF file path
        quality: JPEG quality (0-100), 100 = no compression
    """
    doc = SimpleDocTemplate(output_pdf)
    story = []
    
    for img_path in image_paths:
        if not os.path.exists(img_path):
            continue
            
        # Get image dimensions
        img = Image.open(img_path)
        width, height = img.size
        
        # Convert pt to inch (72 pt = 1 inch)
        width_inch = width / 72
        height_inch = height / 72
        
        # Create image with original quality
        rl_img = RLImage(img_path, width=width_inch, height=height_inch)
        story.append(rl_img)
    
    if story:
        doc.build(story)
    return output_pdf

# Usage
images_to_pdf(
    image_paths=["photo1.jpg", "photo2.png"],
    output_pdf="output.pdf",
    quality=100  # Max quality, no compression
)

Multiple Images to Multi-Page PDF

from reportlab.platypus import SimpleDocTemplate, Image as RLImage
from reportlab.lib.pagesizes import A4
from PIL import Image
import os

def create_pdf_from_images(image_folder, output_pdf):
    """Create multi-page PDF from all images in a folder"""
    doc = SimpleDocTemplate(output_pdf, pagesize=A4)
    story = []
    
    image_exts = ('.jpg', '.jpeg', '.png', '.bmp', '.tiff')
    images = [f for f in os.listdir(image_folder) 
              if f.lower().endswith(image_exts)]
    images.sort()
    
    for img_name in images:
        img_path = os.path.join(image_folder, img_name)
        img = Image.open(img_path)
        width, height = img.size
        width_pt = width * 72 / img.info.get('dpi', 72)
        height_pt = height * 72 / img.info.get('dpi', 72)
        
        rl_img = RLImage(img_path, width=width_pt, height=height_pt)
        story.append(rl_img)
    
    doc.build(story)

# Usage
create_pdf_from_images(r"D:\Photos", "photos.pdf")

Extract Text from Scanned PDFs

# Requires: pip install pytesseract pdf2image
import pytesseract
from pdf2image import convert_from_path

# Convert PDF to images
images = convert_from_path('scanned.pdf')

# OCR each page
text = ""
for i, image in enumerate(images):
    text += f"Page {i+1}:\n"
    text += pytesseract.image_to_string(image)
    text += "\n\n"

print(text)

Add Watermark

from pypdf import PdfReader, PdfWriter

# Create watermark (or load existing)
watermark = PdfReader("watermark.pdf").pages[0]

# Apply to all pages
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)

Extract Images

# Using pdfimages (poppler-utils)
pdfimages -j input.pdf output_prefix

# This extracts all images as output_prefix-000.jpg, output_prefix-001.jpg, etc.

Password Protection

from pypdf import PdfReader, PdfWriter

reader = PdfReader("input.pdf")
writer = PdfWriter()

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

# Add password
writer.encrypt("userpassword", "ownerpassword")

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

Quick Reference

Next Steps

• For advanced pypdfium2 usage, see reference.md
• For JavaScript libraries (pdf-lib), see reference.md
• If you need to fill out a PDF form, follow the instructions in forms.md
• For troubleshooting guides, see reference.md