---
name: pdf-text-extractor
description: "使用OCR支持从PDF中提取文本。"
metadata:
  {
    "openclaw":
      {
        "version": "1.0.0",
        "author": "Vernox",
        "license": "MIT",
        "tags": ["pdf", "ocr", "text", "extraction", "document", "digitization"],
        "category": "tools"
      }
  }
---

# PDF-Text-Extractor - Extract Text from PDFs

**Vernox Utility Skill - Perfect for document digitization.**

## Overview

PDF-Text-Extractor is a zero-dependency tool for extracting text content from PDF files. Supports both embedded text extraction (for text-based PDFs) and OCR (for scanned documents).

## Features

### ✅ Text Extraction
- Extract text from PDFs without external tools
- Support for both text-based and scanned PDFs
- Preserve document structure and formatting
- Fast extraction (milliseconds for text-based)

### ✅ OCR Support
- Use Tesseract.js for scanned documents
- Support multiple languages (English, Spanish, French, German)
- Configurable OCR quality/speed
- Fallback to text extraction when possible

### ✅ Batch Processing
- Process multiple PDFs at once
- Batch extraction for document workflows
- Progress tracking for large files
- Error handling and retry logic

### ✅ Output Options
- Plain text output
- JSON output with metadata
- Markdown conversion
- HTML output (preserving links)

### ✅ Utility Features
- Page-by-page extraction
- Character/word counting
- Language detection
- Metadata extraction (author, title, creation date)

## Installation

```bash
clawhub install pdf-text-extractor
```

## Quick Start

### Extract Text from PDF

```javascript
const result = await extractText({
  pdfPath: './document.pdf',
  options: {
    outputFormat: 'text',
    ocr: true,
    language: 'eng'
  }
});

console.log(result.text);
console.log(`Pages: ${result.pages}`);
console.log(`Words: ${result.wordCount}`);
```

### Batch Extract Multiple PDFs

```javascript
const results = await extractBatch({
  pdfFiles: [
    './document1.pdf',
    './document2.pdf',
    './document3.pdf'
  ],
  options: {
    outputFormat: 'json',
    ocr: true
  }
});

console.log(`Extracted ${results.length} PDFs`);
```

### Extract with OCR

```javascript
const result = await extractText({
  pdfPath: './scanned-document.pdf',
  options: {
    ocr: true,
    language: 'eng',
    ocrQuality: 'high'
  }
});

// OCR will be used (scanned document detected)
```

## Tool Functions

### `extractText`
Extract text content from a single PDF file.

**Parameters:**
- `pdfPath` (string, required): Path to PDF file
- `options` (object, optional): Extraction options
  - `outputFormat` (string): 'text' | 'json' | 'markdown' | 'html'
  - `ocr` (boolean): Enable OCR for scanned docs
  - `language` (string): OCR language code ('eng', 'spa', 'fra', 'deu')
  - `preserveFormatting` (boolean): Keep headings/structure
  - `minConfidence` (number): Minimum OCR confidence score (0-100)

**Returns:**
- `text` (string): Extracted text content
- `pages` (number): Number of pages processed
- `wordCount` (number): Total word count
- `charCount` (number): Total character count
- `language` (string): Detected language
- `metadata` (object): PDF metadata (title, author, creation date)
- `method` (string): 'text' or 'ocr' (extraction method)

### `extractBatch`
Extract text from multiple PDF files at once.

**Parameters:**
- `pdfFiles` (array, required): Array of PDF file paths
- `options` (object, optional): Same as extractText

**Returns:**
- `results` (array): Array of extraction results
- `totalPages` (number): Total pages across all PDFs
- `successCount` (number): Successfully extracted
- `failureCount` (number): Failed extractions
- `errors` (array): Error details for failures

### `countWords`
Count words in extracted text.

**Parameters:**
- `text` (string, required): Text to count
- `options` (object, optional):
  - `minWordLength` (number): Minimum characters per word (default: 3)
  - `excludeNumbers` (boolean): Don't count numbers as words
  - `countByPage` (boolean): Return word count per page

**Returns:**
- `wordCount` (number): Total word count
- `charCount` (number): Total character count
- `pageCounts` (array): Word count per page
- `averageWordsPerPage` (number): Average words per page

### `detectLanguage`
Detect the language of extracted text.

**Parameters:**
- `text` (string, required): Text to analyze
- `minConfidence` (number): Minimum confidence for detection

**Returns:**
- `language` (string): Detected language code
- `languageName` (string): Full language name
- `confidence` (number): Confidence score (0-100)

## Use Cases

### Document Digitization
- Convert paper documents to digital text
- Process invoices and receipts
- Digitize contracts and agreements
- Archive physical documents

### Content Analysis
- Extract text for analysis tools
- Prepare content for LLM processing
- Clean up scanned documents
- Parse PDF-based reports

### Data Extraction
- Extract data from PDF reports
- Parse tables from PDFs
- Pull structured data
- Automate document workflows

### Text Processing
- Prepare content for translation
- Clean up OCR output
- Extract specific sections
- Search within PDF content

## Performance

### Text-Based PDFs
- **Speed:** ~100ms for 10-page PDF
- **Accuracy:** 100% (exact text)
- **Memory:** ~10MB for typical document

### OCR Processing
- **Speed:** ~1-3s per page (high quality)
- **Accuracy:** 85-95% (depends on scan quality)
- **Memory:** ~50-100MB peak during OCR

## Technical Details

### PDF Parsing
- Uses native PDF.js library
- Extracts text layer directly (no OCR needed)
- Preserves document structure
- Handles password-protected PDFs

### OCR Engine
- Tesseract.js under the hood
- Supports 100+ languages
- Adjustable quality/speed tradeoff
- Confidence scoring for accuracy

### Dependencies
- **ZERO external dependencies**
- Uses Node.js built-in modules only
- PDF.js included in skill
- Tesseract.js bundled

## Error Handling

### Invalid PDF
- Clear error message
- Suggest fix (check file format)
- Skip to next file in batch

### OCR Failure
- Report confidence score
- Suggest rescan at higher quality
- Fallback to basic extraction

### Memory Issues
- Stream processing for large files
- Progress reporting
- Graceful degradation

## Configuration

### Edit `config.json`:
```json
{
  "ocr": {
    "enabled": true,
    "defaultLanguage": "eng",
    "quality": "medium",
    "languages": ["eng", "spa", "fra", "deu"]
  },
  "output": {
    "defaultFormat": "text",
    "preserveFormatting": true,
    "includeMetadata": true
  },
  "batch": {
    "maxConcurrent": 3,
    "timeoutSeconds": 30
  }
}
```

## Examples

### Extract from Invoice
```javascript
const invoice = await extractText('./invoice.pdf');
console.log(invoice.text);
// "INVOICE #12345 Date: 2026-02-04..."
```

### Extract from Scanned Contract
```javascript
const contract = await extractText('./scanned-contract.pdf', {
  ocr: true,
  language: 'eng',
  ocrQuality: 'high'
});
console.log(contract.text);
// "AGREEMENT This contract between..."
```

### Batch Process Documents
```javascript
const docs = await extractBatch([
  './doc1.pdf',
  './doc2.pdf',
  './doc3.pdf',
  './doc4.pdf'
]);
console.log(`Processed ${docs.successCount}/${docs.results.length} documents`);
```

## Troubleshooting

### OCR Not Working
- Check if PDF is truly scanned (not text-based)
- Try different quality settings (low/medium/high)
- Ensure language matches document
- Check image quality of scan

### Extraction Returns Empty
- PDF may be image-only
- OCR failed with low confidence
- Try different language setting

### Slow Processing
- Large PDF takes longer
- Reduce quality for speed
- Process in smaller batches

## Tips

### Best Results
- Use text-based PDFs when possible (faster, 100% accurate)
- High-quality scans for OCR (300 DPI+)
- Clean background before scanning
- Use correct language setting

### Performance Optimization
- Batch processing for multiple files
- Disable OCR for text-based PDFs
- Lower OCR quality for speed when acceptable

## Roadmap

- [ ] PDF/A support
- [ ] Advanced OCR pre-processing
- [ ] Table extraction from OCR
- [ ] Handwriting OCR
- [ ] PDF form field extraction
- [ ] Batch language detection
- [ ] Confidence scoring visualization

## License

MIT

---

**Extract text from PDFs. Fast, accurate, zero dependencies.** 🔮