8 PDF Accessibility Issues Automated Tools Miss

Automated PDF accessibility checkers can catch many issues, but did you know they often miss 25-35% of accessibility problems? This gap can lead to significant barriers for users with disabilities.

Recently, a new client approached us with complaints that their PDFs were inaccessible, despite their communication team’s reliance on automated checkers like Acrobat. The client’s PDFs showed no errors according to these tools, yet users were still facing difficulties.

This article highlights eight critical accessibility issues that automated tools often overlook and provides a checklist to ensure your PDFs are genuinely accessible.

1. Misidentified or Missing Headings

Automated tools may confirm the presence of headings, but they cannot verify if they are correctly tagged or if the structure logically reflects the document's content. For example, a document might skip heading levels or misidentify bold text as a heading, leading to confusion for screen reader users.

2. Layout Tables vs. Data Tables

Layout tables, which are used purely for visual arrangement, should be tagged differently than data tables, which convey meaningful information. Automated tools often fail to distinguish between these, causing misinterpretation by assistive technologies.

3. Improperly Tagged Decorative Images

Images that are purely decorative should be tagged as artifacts so that screen readers skip them. Automated checkers often fail to identify these correctly, leaving unnecessary information that can distract or confuse users.

4. Missing or Incorrect Alt Text

While automated tools can detect the presence of alt text, they cannot assess its accuracy or appropriateness. Images might have generic or incorrect alt text, leading to miscommunication or a lack of context for users relying on screen readers.

5. Inadequate Table Header Associations

Data tables must have clear relationships between header cells and their corresponding data cells. Automated tools often miss incorrect or incomplete associations, which can make the data unintelligible to screen readers.

6. Overlooked Reading Order

The correct reading order is crucial, especially for documents with complex layouts. Automated tools cannot reliably determine the intended reading flow, leading to a confusing experience for users navigating the document with assistive technologies.

7. Missing Language Attributes

Documents containing multiple languages or sections in different languages need specific language attributes set for each section. Automated tools might fail to identify language changes within a document, leading to incorrect pronunciation or translation by screen readers.

8. Unclear Form Field Descriptions

Form fields need clear, descriptive tooltips to guide users, especially those using screen readers. Automated checkers can detect the presence of tooltips but cannot assess their clarity or completeness, often leaving users confused about what is required in each field.

Conclusion

Automated tools like PAC or Acrobat Checker are valuable for identifying many accessibility issues, but they are not foolproof. Ensuring full accessibility requires manual checks, especially for complex elements like headings, tables, and reading order. By addressing these commonly missed issues, you can provide a better experience for all users.

Checklist for Ensuring PDF Accessibility

• Verify that headings are correctly tagged and structured.
• Ensure layout tables are properly differentiated from data tables.
• Tag decorative images as artifacts.
• Review alt text for accuracy and context.
• Confirm table header associations are complete and correct.
• Manually set the correct reading order.
• Assign language attributes for multilingual content.
• Provide clear and descriptive tooltips for all form fields.