The Scanned PDF Problem
Many PDFs are actually images - scanned documents that look like text but can't be selected or searched. You've seen this when:
- Ctrl+F finds nothing in a document you know contains the text
- You can't select or copy any text
- The file came from a scanner or fax
These are "image PDFs" and need OCR to extract the text.
What You'll Need
- Your scanned PDF or document image
- An OCR tool (we'll use TextFromImage)
- Optionally: Software to export PDF pages as images
Step-by-Step Guide
Step 1: Prepare Your Document
If it's already an image (JPG, PNG):
Skip to Step 2.
If it's a scanned PDF:
Export pages as images:
- Mac Preview: File → Export → Format: PNG
- Adobe Reader: File → Export → Image
- Online tools: pdf2jpg.net or similar
Step 2: Upload to TextFromImage
- Go to textfromimage.app
- Upload your document image
- Wait for processing
Step 3: Review and Edit
Check the extracted text for:
- Formatting issues
- Misread characters
- Table structure (may need manual fixing)
Document Types and Tips
Contracts and Legal Documents
- Usually clean typed text - high accuracy
- Watch for signatures being misread
- Section numbers and references need verification
Invoices and Financial Documents
- Numbers need careful verification
- Tables may need reformatting
- Currency symbols can be tricky
Old or Historical Documents
- Older fonts may be challenging
- Faded text reduces accuracy
- Consider image enhancement first
Forms with Handwriting
- Printed portions extract well
- Handwritten fields may need manual entry
- Mixed documents need extra review
Improving OCR Accuracy
Image Quality
- 300 DPI minimum for scanning
- Black and white for text documents
- Color only if needed for context
Pre-processing
- Straighten skewed scans
- Increase contrast if text is faded
- Crop to content area
Post-processing
- Use spell-check to catch errors
- Search-replace common OCR mistakes (rn→m, 0→O)
- Verify numbers manually
Batch Processing Workflow
For many documents:
- Scan all documents at once
- Export each page as separate image
- Process through OCR
- Review each for accuracy
- Combine into final format
Common Issues
Problem: Text is recognized but jumbled
Solution: Multi-column documents confuse OCR. Process columns separately.
Problem: Very low accuracy
Solution: Image may be too low quality. Try to get a better scan or original digital version.
Problem: Tables lose structure
Solution: Table layout is challenging for OCR. You may need to manually recreate in a spreadsheet.
Legal and Compliance Considerations
When digitizing business documents:
- Keep original scans as record
- Note that OCR text is a transcription, not the legal document
- For critical documents, verify every character
- Maintain document chain of custody
Conclusion
Converting scanned documents to text unlocks their value. Instead of unsearchable image files, you get editable, searchable, usable text.
The key is starting with the best quality scan possible and verifying the output for accuracy.