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skills/pdf-processing-pro/OCR.md

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+# PDF OCR Processing Guide
+
+Extract text from scanned PDFs and image-based documents.
+
+## Quick start
+
+```python
+import pytesseract
+from pdf2image import convert_from_path
+from PIL import Image
+
+# Convert PDF to images
+images = convert_from_path("scanned.pdf")
+
+# Extract text from each page
+for i, image in enumerate(images):
+    text = pytesseract.image_to_string(image)
+    print(f"Page {i+1}:\n{text}\n")
+```
+
+## Installation
+
+### Install Tesseract
+
+**macOS:**
+```bash
+brew install tesseract
+```
+
+**Ubuntu/Debian:**
+```bash
+sudo apt-get install tesseract-ocr
+```
+
+**Windows:**
+Download from: https://github.com/UB-Mannheim/tesseract/wiki
+
+### Install Python packages
+
+```bash
+pip install pytesseract pdf2image pillow
+```
+
+## Language support
+
+```python
+# English (default)
+text = pytesseract.image_to_string(image, lang="eng")
+
+# Spanish
+text = pytesseract.image_to_string(image, lang="spa")
+
+# Multiple languages
+text = pytesseract.image_to_string(image, lang="eng+spa+fra")
+```
+
+Install additional languages:
+```bash
+# macOS
+brew install tesseract-lang
+
+# Ubuntu
+sudo apt-get install tesseract-ocr-spa tesseract-ocr-fra
+```
+
+## Image preprocessing
+
+```python
+from PIL import Image, ImageEnhance, ImageFilter
+
+def preprocess_for_ocr(image):
+    """Optimize image for better OCR accuracy."""
+
+    # Convert to grayscale
+    image = image.convert("L")
+
+    # Increase contrast
+    enhancer = ImageEnhance.Contrast(image)
+    image = enhancer.enhance(2.0)
+
+    # Denoise
+    image = image.filter(ImageFilter.MedianFilter())
+
+    # Sharpen
+    image = image.filter(ImageFilter.SHARPEN)
+
+    return image
+
+# Usage
+image = Image.open("scanned_page.png")
+processed = preprocess_for_ocr(image)
+text = pytesseract.image_to_string(processed)
+```
+
+## Best practices
+
+1. **Preprocess images** for better accuracy
+2. **Use appropriate language** models
+3. **Batch process** large documents
+4. **Cache results** to avoid re-processing
+5. **Validate output** - OCR is not 100% accurate
+6. **Consider confidence scores** for quality checks
+
+## Production example
+
+```python
+import pytesseract
+from pdf2image import convert_from_path
+from PIL import Image
+
+def ocr_pdf(pdf_path, output_path):
+    """OCR PDF and save to text file."""
+
+    # Convert to images
+    images = convert_from_path(pdf_path, dpi=300)
+
+    full_text = []
+
+    for i, image in enumerate(images, 1):
+        print(f"Processing page {i}/{len(images)}")
+
+        # Preprocess
+        processed = preprocess_for_ocr(image)
+
+        # OCR
+        text = pytesseract.image_to_string(processed, lang="eng")
+        full_text.append(f"--- Page {i} ---\n{text}\n")
+
+    # Save
+    with open(output_path, "w", encoding="utf-8") as f:
+        f.write("\n".join(full_text))
+
+    print(f"Saved to {output_path}")
+
+# Usage
+ocr_pdf("scanned_document.pdf", "extracted_text.txt")
+```