Scanned / Image-Only PDF

Who Is Affected

Blind users who rely on screen readers, users with cognitive disabilities who need text-to-speech software, users who need to magnify text content, and anyone trying to search within the document or copy text for translation.

What This Means

A scanned PDF is essentially a photograph of a document — it looks like text to human eyes, but to assistive technology, it's just an image. Screen readers cannot extract or read the text content, making the entire document inaccessible.

These PDFs are typically created by scanning paper documents, receiving faxed materials, or photocopying existing documents. While they preserve the visual appearance of the original, they create complete accessibility barriers.

The complexity and time required for remediation depends on document length, text quality, formatting complexity, and whether tables or forms are present.

Fix: Document

Step 1: Assess Document Quality

1. Check if the scanned text is clear and high-contrast
2. Verify that text is not skewed or distorted
3. Confirm the document is in a readable resolution (300 DPI minimum)
4. If quality is poor, rescan the original document if available

Step 2: Perform OCR (Optical Character Recognition)

1. Open the PDF in Adobe Acrobat Pro
2. Go to Tools → Enhance Scans → Recognize Text
3. Select "In This File" and choose appropriate settings:
   • Language: Match your document's language
   • Output: Searchable Image (Exact) for best results
4. Run the OCR process
5. Review the Results panel for any recognition errors

Step 3: Manual Text Correction

1. Use Find & Replace to fix systematic OCR errors (common: "rn" recognized as "m")
2. Manually correct any garbled text, especially in headers and important content
3. Pay special attention to:
   • Numbers and dates
   • Names and proper nouns
   • Technical terms or acronyms

Step 4: Add Document Structure

1. Use the Tags panel to add proper heading structure
2. Tag any tables with appropriate table tags
3. Add alternative text for any images or charts
4. Set the document title and language in Document Properties

Step 5: Test Accessibility

1. Use the Accessibility Checker in Acrobat (Tools → Accessibility → Full Check)
2. Test with a screen reader like NVDA to ensure content flows logically
3. Verify that all text is selectable and readable

Alternative Approach for Complex Documents: For documents with complex formatting, consider recreating the content in an accessible format like HTML or a properly structured Word document, then converting to tagged PDF.

Standard Reference

Related WCAG 2.1 Success Criteria:

• 1.1.1 Non-text Content (Level A) — Images of text require text alternatives
• 1.3.1 Info and Relationships (Level A) — Document structure must be programmatically determinable
• 1.3.2 Meaningful Sequence (Level A) — Content must have a logical reading order

PDF Techniques:

• PDF7 — Performing OCR on a scanned PDF document
• PDF9 — Providing headings by marking content with heading tags
• G94 — Providing short text alternative for non-text content

Common Failure:

• F72 — Images of text without alternative text