如何在Python Tika中忽略含扫描图像的PDF文件？

Got it, let's work through this. Since you've disabled Tesseract and don't want those scanned handwritten PDFs spitting out garbage text, here are practical ways to detect and skip them:

1. Detect via Tika Metadata + Content Length #

Scanned PDFs rarely have native text, so we can check if the extracted content is nearly empty, and cross-reference with image/page counts from Tika's metadata:

from tika import parser

def is_scanned_pdf(file_path):
    parsed_data = parser.from_file(file_path)
    metadata = parsed_data['metadata']
    raw_content = parsed_data['content'] or ""
    
    # First check if the content is mostly blank
    cleaned_content = raw_content.strip()
    if len(cleaned_content) < 100:  # Adjust threshold based on your use case
        # Check if image count matches (or is close to) page count
        image_count = int(metadata.get('pdf:images', '0'))
        total_pages = int(metadata.get('xmpTPg:NPages', '1'))
        if image_count >= total_pages:
            return True
    return False

# Usage example
target_pdf = "your_document.pdf"
if is_scanned_pdf(target_pdf):
    print(f"Skipping scanned PDF: {target_pdf}")
else:
    # Proceed with normal parsing
    processed_content = parser.from_file(target_pdf)['content']

This works because most scanned PDFs have one image per page and almost no extractable text. Tweak the 100-character threshold to fit your typical document lengths.

2. Use a PDF-Specific Library to Check for Text #

Libraries like pdfplumber are great for directly checking if pages contain extractable text. If a page has no text, it's almost certainly an image scan:

import pdfplumber

def is_image_dominant_pdf(file_path):
    with pdfplumber.open(file_path) as pdf:
        for page in pdf.pages:
            page_text = page.extract_text() or ""
            if len(page_text.strip()) == 0:
                # At least one page is image-only; mark the whole PDF for skipping
                return True
    return False

# Usage example
if is_image_dominant_pdf(target_pdf):
    print(f"Skipping image-heavy PDF: {target_pdf}")
else:
    # Parse with Tika as usual
    parsed_content = parser.from_file(target_pdf)['content']

If you need more nuance (e.g., skip only if 70%+ pages are image-only), you can count the number of blank pages and compare to total pages.

3. Combine Content Check with File Size Heuristics #

Scanned PDFs are usually larger than text-only PDFs because they store image data. Pairing content length with file size can reduce false positives:

import os
from tika import parser

def should_skip_pdf(file_path):
    # Get file size in MB
    file_size_mb = os.path.getsize(file_path) / (1024 * 1024)
    parsed_data = parser.from_file(file_path)
    content_length = len(parsed_data['content'].strip()) if parsed_data['content'] else 0
    
    # Adjust thresholds based on your typical documents
    if file_size_mb > 2 and content_length < 200:
        return True
    return False

This is a secondary check—use it alongside the methods above for more reliability.

Notes #

• These are heuristic checks, so there's no perfect 100% accuracy, but they'll cover most real-world cases.
• If you have mixed PDFs (some text pages, some scanned), you might want to skip just the image pages instead of the whole document, but that requires more granular page-by-page processing.

内容的提问来源于stack exchange，提问作者pramesh