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How to extract text from documents

Writer's picture: Virtual Flow Virtual Flow

Imagine you’ve just scanned a stack of paper invoices—some a bit crooked, others with faded text—and you need to quickly capture the relevant details without typing them out. Or perhaps you’re hunting for a specific clause in a scanned contract but your PDF viewer can’t search through images. These scenarios highlight where Optical Character Recognition (OCR) becomes invaluable. By using OCR technology, you can transform seemingly impenetrable image-based PDFs into fully editable, searchable, and analyzable digital text.




The Power of OCR

OCR stands for Optical Character Recognition, a technology that “reads” the text in images and converts it into machine-readable text. This breakthrough has saved countless hours that would otherwise be spent retyping handwritten or scanned text. Whether you’re dealing with archival documents, handwritten notes, or forms that were scanned instead of digitally created, OCR bridges the gap between physical print and digital efficiency.


Real-World Use Cases

  1. Financial and Accounting: Organizations dealing with receipts, invoices, and billing statements use OCR to streamline data entry, minimize errors, and automate bookkeeping processes.

  2. Legal and Compliance: Legal firms and compliance teams can rapidly search through large volumes of scanned legal documents, contracts, or case files for keywords and clauses.

  3. Healthcare: Hospitals and clinics rely on OCR to digitize patient records and insurance forms, making it easier to access, update, and share critical medical information.

  4. Education and Research: Students and researchers can quickly extract quotes or references from books and scholarly articles that are only available in scanned format.


Exploring Your OCR Options

Choosing the right OCR tool depends on your workflow, budget, and desired accuracy. Several technologies stand out:

  • AWS Textract: An Amazon Web Services product specifically designed to handle not only raw text extraction but also complex structures like tables and forms. Because of its machine learning underpinnings, Textract can identify key-value pairs (like fields and corresponding values in a form) and maintain layout integrity. Integrating it with other AWS services (like S3 for storage) is straightforward, making it a robust solution for large-scale, automated document processing pipelines.

  • Tesseract OCR: A free, open-source OCR engine maintained by Google. For those who value full control over data (e.g., sensitive information you’d rather not upload to the cloud), Tesseract can be installed and run locally. While it may require some setup—and possibly training for custom fonts or less common languages—it’s an excellent solution that has been battle-tested for years.

  • Google Cloud Vision: Google’s cloud-based offering excels at text recognition and broader image analysis, capable of detecting objects, logos, and landmarks. It’s a good fit if you want a single platform for all image-related machine learning tasks, including OCR, or if you’re already using the Google Cloud ecosystem.

  • Microsoft Azure Cognitive Services: Ideal for teams that rely on Microsoft’s cloud services. Its OCR functionality supports multiple languages and can be combined with other AI-driven services like text analytics. This is a solid choice for enterprise-scale document management in a Microsoft-focused environment.


Getting Started: A Practical Workflow

Suppose you have a batch of scanned PDFs you want to convert into searchable text. You might start by uploading them to a cloud storage service—like Amazon S3—if you’re using AWS Textract. From there, you’d invoke the Textract API, which processes each page and returns the extracted text and information about its structure (tables, form fields, etc.). Afterward, you could store this extracted data in a database or pass it on to another application that handles analytics or archiving.

If, however, you prefer to keep everything in-house, you could install Tesseract OCR on your local machine. You’d then run each PDF or image through Tesseract, specifying the language, resolution, and any custom-trained data files. The result would be a plain text file (or searchable PDF) that you can easily search or edit.


Best Practices for Optimal Results

  • High-Quality Scans: Aim for at least 300 dpi and clear contrast; poor resolution can cause OCR tools to misread text.

  • Consistent Formatting: Keep documents aligned and avoid cutting off edges. The more uniform each page is, the better the OCR performance.

  • Language and Font Considerations: Some OCR engines need training data for unusual fonts or scripts. Spend the time to fine-tune for your language needs.

  • Validation and Post-Processing: Always review the extracted text—especially if it contains sensitive or mission-critical information. Manual spot checks can catch errors before they propagate through your workflow.


Conclusion

From legal firms needing quick keyword searches in lengthy case files to medical institutions aiming for seamless patient record digitization, OCR fundamentally changes the way we handle scanned documents. By choosing a tool that fits your technical requirements—whether it’s AWS Textract for large-scale, structured data extraction, or Tesseract for a flexible, open-source approach—you unlock a new level of efficiency.



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