pdf-extraction-fallback

PDF Extraction Fallback Strategy

When processing documents (especially PDFs), initial extraction attempts may fail due to formatting, encryption, or tool limitations. This skill provides a systematic fallback approach that tries multiple extraction methods before declaring failure.

Core Principle

Never declare completion after a single tool failure. Instead, iterate through a hierarchy of extraction methods, each with different capabilities and limitations.

Fallback Hierarchy

Attempt extraction methods in this order:

Stage 1: Direct PDF Reading

Try native PDF libraries first (fastest, preserves structure):

import PyPDF2
from pypdf import PdfReader

def extract_with_pypdf(pdf_path):
    reader = PdfReader(pdf_path)
    text = ""
    for page in reader.pages:
        text += page.extract_text() or ""
    return text

Stage 2: Shell-based Extraction (pdftotext)

If Stage 1 fails, use system tools:

# Install if needed: apt-get install poppler-utils
pdftotext -layout input.pdf output.txt
pdftotext -raw input.pdf output.txt  # Alternative layout

import subprocess

def extract_with_pdftotext(pdf_path):
    result = subprocess.run(
        ['pdftotext', '-layout', pdf_path, '-'],
        capture_output=True, text=True
    )
    if result.returncode == 0:
        return result.stdout
    raise Exception("pdftotext failed")

Stage 3: Alternative Python Parsers

Try different Python libraries with varying capabilities:

# pdfplumber - better for tables
import pdfplumber
def extract_with_pdfplumber(pdf_path):
    text = ""
    with pdfplumber.open(pdf_path) as pdf:
        for page in pdf.pages:
            text += page.extract_text() or ""
    return text

# pdfminer - handles complex layouts
from pdfminer.high_level import extract_text
def extract_with_pdfminer(pdf_path):
    return extract_text(pdf_path)

Stage 4: OCR Fallback

For scanned images or when text extraction fails:

# Using tesseract
convert input.pdf output-%d.png  # Convert to images first
tesseract output-0.png result --psm 6