Extract ISBNs from scanned books

Extracting ISBNs from scanned books involves several steps, typically including image processing, text recognition (OCR), and pattern matching to isolate the ISBN number. Here’s a detailed guide on how to do it:

1. Preprocess the Scanned Images

• Enhance image quality: Use filters to improve contrast and clarity.

• Deskew and straighten: Correct any tilt in the scanned page to improve OCR accuracy.

• Crop to relevant area: ISBNs usually appear on the book’s cover, title page, or back cover.

2. Optical Character Recognition (OCR)

• Use OCR tools like Tesseract (open-source), Google Vision API, or Amazon Textract to convert scanned images into machine-readable text.

• Make sure to configure OCR for:

  • High accuracy

  • Focus on numeric and alphanumeric strings

3. Extract ISBN Patterns

• ISBNs are standardized formats:

  • ISBN-10: 10 digits, sometimes with dashes or spaces (e.g., 0-123456-47-9)

  • ISBN-13: 13 digits, often starting with 978 or 979 (e.g., 978-3-16-148410-0)

• Use regular expressions to find matches in the OCR text, e.g.:

regex
CopyEdit
(?:ISBN(?:-13)?:?s*)?((97(8|9))?d{9}(d|X))

Or more elaborate regex to match dashes and spaces:

regex
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ISBN(?:-1[03])?:?s*((97(8|9))?[-s]?d{1,5}[-s]?d{1,7}[-s]?d{1,7}[-s]?[dX])

4. Validate ISBNs

• Check the extracted number against the ISBN checksum rules to ensure validity.

• ISBN-10 checksum: weighted sum modulo 11

• ISBN-13 checksum: weighted sum modulo 10

5. Automation and Tools

• Combine these steps in a script or pipeline.

• Python example libraries:

  • pytesseract for OCR

  • re for regex extraction

  • isbnlib for ISBN validation and conversion

If you want, I can provide a Python script example that extracts ISBNs from images using OCR and regex. Would you like that?