What Is a Scanned PDF and How to Make It Accessible?

What Is a Scanned PDF?

A scanned PDF is created when a paper document is scanned and saved as a PDF file. Instead of real, selectable text, the file contains images of each page.

Because the text is embedded inside images, screen readers and other assistive technologies cannot read, search, or navigate the content. This makes a scanned PDF inaccessible by default for users who rely on assistive tools.

How to Make a Scanned PDF Accessible?

Creating an accessible scanned PDF requires more than converting images into text. It involves adding structure, semantics, and navigational cues so that assistive technologies can interpret the content correctly.

Here’s how you can make a scanned PDF accessible:

1. Perform OCR (Optical Character Recognition)

OCR converts images of text into machine-readable characters, allowing the content to be searched, selected, and read aloud by screen readers.

For a fully accessible scanned PDF, OCR accuracy is critical. Poor results can introduce reading errors, incorrect characters, or broken words, which directly impact accessibility. Tools such as PREP are commonly used in professional workflows to apply OCR at scale while maintaining accuracy.

2. Add Accessibility Tags and Structural Elements

Simply performing OCR is not enough. The document still lacks semantic meaning. Accessibility tags define headings, paragraphs, lists, tables, and other structural components. These allow assistive technologies to understand how content is organized.

Without proper tagging, even OCR-processed documents behave like unstructured text streams, making navigation difficult for users.

3. Fix the Reading Order

In a scanned PDF, visual layout does not guarantee logical reading order because screen readers follow a tag order, not the visual placement of content.

To make the content flow logically from top to bottom and left to right, the reading order must be corrected. This step is especially important in multi-column layouts, forms, and documents with sidebars or footnotes.

4. Add Alternative Text for Images

If the document contains images, charts, icons, or diagrams, meaningful alternative text must be provided. Alt text ensures that non-text content is communicated to users who cannot see it.

In addition to this, decorative images should be marked as artifacts so they are ignored by assistive technologies and do not interrupt reading flow.

5. Make Tables Accessible

Tables in a scanned PDF often lose all semantic relationships during scanning. To restore accessibility, tables must include proper header cells, defined row and column relationships, and logical structure.

6. Ensure Sufficient Color Contrast and Readable Fonts

Low contrast text and decorative fonts reduce readability for users with low vision or cognitive disabilities. Text should meet contrast requirements and use simple, legible fonts.This step improves accessibility not only for assistive technology users but also for users reading on small screens or in low-visibility environments.

7. Enable Keyboard Navigation

All interactive elements in an accessible scanned PDF, such as links and form fields, must be reachable using a keyboard alone. Keyboard accessibility is essential for users with motor disabilities and screen reader users.

8. Set Document Title and Language Metadata

The document title helps screen reader users identify the file among multiple open documents. Language metadata ensures correct pronunciation and reading rules.If language is not defined, assistive technologies may mispronounce words or apply incorrect speech patterns.

9.  Test with Screen Readers and Assistive Technology

Automated checks cannot replace real-world testing. Screen reader testing reveals issues such as confusing navigation, repeated content, or missing context that automated tools may miss.

Testing confirms whether the accessible scanned PDF works as intended for real users.

10. Run an Accessibility Checker

As a final step, the document should be evaluated using an accessibility checker to identify remaining technical issues.

Professional workflows often combine manual testing with tools such as the PDF Accessibility Checker available in PREP to validate compliance and consistency.

Closing Thoughts

A scanned PDF may look complete, but without OCR, structure, and accessibility enhancements, it excludes a large group of users. Creating an accessible scanned PDF is a multi-step process that combines technology, standards knowledge, and validation.

As accessibility regulations expand globally and expectations rise, treating scanned documents as first-class digital content is no longer optional. Building accessibility into scanned PDFs ensures information remains usable, compliant, and inclusive for everyone.