PDF Processing

Step 1: Identify the Task

Match the user's request to one workflow. Default to Extract Text when unclear.

Task	Primary Tool	Fallback
Extract text	pdfplumber	pdftotext CLI
Extract tables to DataFrame	pdfplumber + pandas	--
OCR scanned PDFs	pytesseract + pdf2image	--
Create new PDF	reportlab (Platypus for complex, Canvas for simple)	--
Merge/split/rotate	pypdf	qpdf CLI
Add watermark	pypdf merge_page()	--
Password protect/decrypt	pypdf encrypt()/qpdf	--
Fill PDF forms	Read references/forms.md and follow its steps	--
Markdown to PDF	python scripts/md_to_pdf.py input.md output.pdf	--
Batch markdown to PDF	python scripts/batch_convert.py *.md --output-dir ./pdfs/	--
Extract images	pdfimages -j input.pdf output_prefix (poppler-utils)	pypdfium2
Render pages to images	pypdfium2	pdftoppm CLI

Step 2: Install Dependencies

Check what is available before writing code:

pip list 2>/dev/null | grep -iE "pypdf|pdfplumber|reportlab|pypdfium2|weasyprint|pytesseract|pdf2image"
which pdftotext qpdf pdftk pdfimages 2>/dev/null

Install only what the task needs. Do not install everything.

Task	Install
Text/table extraction	pip install pdfplumber
OCR	pip install pytesseract pdf2image + system poppler
Merge/split/rotate/encrypt	pip install pypdf
Create PDFs	pip install reportlab
Render to images	pip install pypdfium2
Markdown to PDF	pip install weasyprint markdown

Step 3: Execute the Workflow

Use the code patterns in references/cookbook.md for implementation details.
Use references/advanced-features.md for pypdfium2, pdf-lib (JS), and advanced CLI operations.

Validation Checkpoints

Run these checks at each stage:

After extraction:

text = page.extract_text()
if not text or len(text.strip()) < 10:
    # PDF may be scanned -- fall back to OCR
    print(f"Page {i+1}: no text found, switching to OCR")

After merge/split:

result = PdfReader("output.pdf")
print(f"Output has {len(result.pages)} pages")
# Verify page count matches expectation

After form fill:
Run the validation scripts described in references/forms.md before delivering the output.

After markdown-to-PDF:

import os
output_size = os.path.getsize("output.pdf")
print(f"Generated PDF: {output_size} bytes")
if output_size < 500:
    print("Warning: PDF seems too small, check for conversion errors")

Step 4: Deliver Results

• Report what was done: page count, text length, file size.
• If OCR was used, warn the user about potential accuracy issues.
• For form fills, note which fields were populated and which were skipped.

**User:** "Extract all the tables from this PDF and save as Excel"

Steps:

1. Install pdfplumber and pandas.
2. Extract tables from each page.
3. Validate each table has rows before saving.
4. Combine and export to Excel.

import pdfplumber
import pandas as pd

with pdfplumber.open("document.pdf") as pdf:
    all_tables = []
    for i, page in enumerate(pdf.pages):
        tables = page.extract_tables()
        for table in tables:
            if table and len(table) > 1:
                df = pd.DataFrame(table[1:], columns=table[0])
                all_tables.append(df)
                print(f"Page {i+1}: extracted table with {len(df)} rows")
    if all_tables:
        combined = pd.concat(all_tables, ignore_index=True)
        combined.to_excel("tables.xlsx", index=False)
        print(f"Saved {len(combined)} total rows to tables.xlsx")
    else:
        print("No tables found in this PDF")

**User:** "Merge these three PDFs into one"

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)
    print(f"Added {len(reader.pages)} pages from {pdf_file}")

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

# Verify
result = PdfReader("merged.pdf")
print(f"Merged PDF has {len(result.pages)} pages")

**User:** "This PDF is scanned, I need the text"

import pytesseract
from pdf2image import convert_from_path

images = convert_from_path("scanned.pdf", dpi=300)
text = ""
for i, image in enumerate(images):
    page_text = pytesseract.image_to_string(image)
    text += page_text
    print(f"Page {i+1}: extracted {len(page_text)} characters")

with open("extracted.txt", "w") as f:
    f.write(text)
print(f"Total: {len(text)} characters. Review for OCR errors.")

**User:** "Convert this markdown file to PDF"

# macOS may need: export DYLD_LIBRARY_PATH=$(brew --prefix)/lib
python scripts/md_to_pdf.py report.md report.pdf

Features: A4 pages, proper margins, table/code support, Chinese font fallback.
For batch conversion: python scripts/batch_convert.py *.md --output-dir ./pdfs/

**User:** "Fill out this PDF form with my details"

Follow the complete workflow in references/forms.md. Summary:

1. Check if the PDF has fillable fields: python scripts/check_fillable_fields.py form.pdf
2. If fillable: extract field info, create values JSON, run fill script.
3. If not fillable: convert to images, identify fields visually, create bounding boxes, validate, fill with annotations.

References

File	Purpose
references/cookbook.md	Python and CLI code patterns for all PDF operations
references/advanced-features.md	pypdfium2, pdf-lib (JS), advanced CLI, performance tips
references/forms.md	Complete form-filling workflow (fillable and non-fillable PDFs)

Scripts

Script	Purpose	Usage
scripts/md_to_pdf.py	Markdown to PDF with Chinese font support	python scripts/md_to_pdf.py input.md [output.pdf]
scripts/batch_convert.py	Batch markdown to PDF	python scripts/batch_convert.py *.md [--output-dir dir]
scripts/check_fillable_fields.py	Check if PDF has fillable form fields	python scripts/check_fillable_fields.py input.pdf
scripts/extract_form_field_info.py	Extract form field metadata to JSON	python scripts/extract_form_field_info.py input.pdf output.json
scripts/fill_fillable_fields.py	Fill fillable PDF form fields	python scripts/fill_fillable_fields.py input.pdf values.json output.pdf
scripts/fill_pdf_form_with_annotations.py	Fill non-fillable PDFs with text annotations	python scripts/fill_pdf_form_with_annotations.py input.pdf fields.json output.pdf
scripts/convert_pdf_to_images.py	Convert PDF pages to PNG images	python scripts/convert_pdf_to_images.py input.pdf output_dir
scripts/create_validation_image.py	Create bounding box validation images	python scripts/create_validation_image.py page_num fields.json input.png output.png
scripts/check_bounding_boxes.py	Validate bounding boxes do not overlap	python scripts/check_bounding_boxes.py fields.json