Checkpoint 13: Graphics

Images and figures in your PDF must have alternative text so that people who cannot see them can still understand the visual content.

What This Means

When you add images, charts, diagrams, or other graphics to a PDF, people who use screen readers cannot see them. Screen readers are software that reads content aloud for people who are blind or have low vision. Without alternative text (often called "alt text"), these users hear nothing about your images or get unhelpful announcements like "graphic" or "image."

Alternative text is a short description that explains what an image shows and why it matters in context. When you provide good alt text, screen reader users get the same information as everyone else.

Why It Matters

Approximately 285 million people worldwide are visually impaired, including 39 million who are blind. When your PDFs lack alternative text for images:

• Blind users miss critical information that may be essential to understanding your document
• Low vision users who rely on screen readers cannot access visual content
• Search engines and indexing tools cannot understand or categorize your images
• Your organization may face legal liability under accessibility laws like the ADA, Section 508, or EN 301 549

Beyond compliance, providing alt text is simply good communication. If an image is important enough to include, it is important enough to describe.

Common Violations

The Matterhorn Protocol defines seven failure conditions for graphics. Here is what each one means and how to fix it.

13-001: Untagged Graphics

What's Wrong: A graphic that conveys meaning is not tagged with a Figure tag. The image exists in the PDF but is invisible to assistive technology.

How to Identify:

• Run the Accessibility Checker in Adobe Acrobat (Tools > Accessibility > Accessibility Check)
• Look for images that appear visually but are not listed in the Tags panel
• Screen reader users report that content is missing

How to Fix:

1. Open the Tags panel in Adobe Acrobat (View > Show/Hide > Navigation Panes > Tags)
2. Use the Reading Order tool (Tools > Accessibility > Reading Order)
3. Draw a box around the untagged image
4. Click the "Figure" button to tag it as a figure
5. Add alternative text to the new Figure tag (see 13-004 below)

13-002: Links with Meaningful Backgrounds Missing Alt Text

What's Wrong: A clickable link uses a background image to convey meaning, but no alternative text describes that image. Users who cannot see the background do not know what the link represents.

How to Identify:

• Look for linked images or icons that serve as buttons
• Check whether clickable areas have descriptive text or rely solely on visual appearance
• Test with a screen reader to hear what is announced for each link

How to Fix:

1. In the Tags panel, locate the Link tag containing the image
2. Right-click on the Figure tag inside the Link tag
3. Select "Properties" and go to the "Tag" tab
4. Add descriptive alternative text that explains both the image and the link destination
5. Example: "Download Annual Report (PDF)" not just "arrow icon"

13-003: Captions Not Tagged as Captions

What's Wrong: Text that serves as a caption for an image is not tagged with a Caption tag. Screen readers cannot associate the caption with its figure, and users may not understand which text describes which image.

How to Identify:

• Look at your document structure in the Tags panel
• Check whether descriptive text below or above images is tagged as Caption
• Captions should be nested within or associated with their parent Figure tags

How to Fix:

1. In the Tags panel, find the text that serves as a caption
2. If it is tagged as a paragraph (P tag), right-click and select "Properties"
3. Change the "Type" from "P" to "Caption"
4. Drag the Caption tag so it is nested inside or immediately follows its Figure tag
5. The structure should look like: Figure > (image content) + Caption

13-004: Figure Tag Missing Alternative Text (Machine Testable)

What's Wrong: An image is correctly tagged as a Figure, but no alternative text or replacement text has been added. This is the most common graphics violation and is automatically detected by PDF accessibility checkers.

How to Identify:

• Run the PDF/UA validation in Adobe Acrobat or use a tool like PAC (PDF Accessibility Checker)
• The checker will report "Figure element has no alternative text" or similar
• In the Tags panel, Figure tags without alt text show no tooltip when you hover over them

How to Fix:

1. In the Tags panel, right-click on the Figure tag
2. Select "Properties"
3. Go to the "Tag" tab
4. In the "Alternate Text" field, enter a description of the image
5. Click "Close"

Writing Good Alt Text:

• Describe what the image shows, not what it is ("Bar chart showing Q3 sales increased 15%" not "chart")
• Keep it concise but complete (typically 125 characters or fewer)
• Include relevant details that matter in context
• For decorative images that add no meaning, mark them as artifacts instead (see below)

13-005: Actual Text Used Instead of Alternative Text

What's Wrong: A figure contains "Actual Text" when "Alternative Text" would be more appropriate. Actual text is for images of text that should be read literally (like a scanned letter). Alternative text is for describing visual content.

How to Identify:

• In the Tags panel, check Figure properties
• If "Actual Text" is filled in for a photograph, diagram, or non-text image, this is incorrect
• Actual text should only be used when the image literally contains text that should be read as-is

How to Fix:

1. Right-click on the Figure tag and select "Properties"
2. Go to the "Tag" tab
3. Clear the "Actual Text" field
4. Enter an appropriate description in the "Alternate Text" field
5. Click "Close"

When to Use Each:

• Alternative Text: Photos, illustrations, charts, diagrams (describe what it shows)
• Actual Text: Images of text, logos with text, scanned documents (provide the literal text content)

13-006: Grouped Graphics Tagged Individually

What's Wrong: A group of images that only makes sense together has been tagged as separate figures. Each individual piece lacks meaning without the others, making the content confusing for screen reader users.

How to Identify:

• Look for diagrams or infographics split into multiple Figure tags
• Check if related images (like a flowchart with multiple components) are tagged separately
• Screen reader testing reveals disconnected, confusing announcements

How to Fix:

1. In the Tags panel, select all the Figure tags that belong together
2. Create a new Figure tag to contain them (right-click > New Tag)
3. Drag the individual figures inside the new container tag
4. Add comprehensive alternative text to the parent Figure tag that describes the complete graphic
5. Consider whether individual components also need their own descriptions, or should be marked as artifacts

13-007: More Accessible Representation Not Used

What's Wrong: A complex graphic could be presented in a more accessible format, but it is not. For example, data that is shown only as an image of a chart could also be provided as an accessible table.

How to Identify:

• Look for images of tables, charts, or data that could be actual tables
• Check whether complex diagrams have supporting text explanations
• Consider whether screen reader users can access all the information

How to Fix:

1. For charts and graphs: Include the underlying data as an accessible table nearby
2. For complex diagrams: Provide a detailed text description in the document body
3. For infographics: Consider breaking into smaller, individually described components
4. Add a long description using the "Alternate Text" field or link to supplementary content

How to Fix in Adobe Acrobat

Adobe Acrobat Pro provides several tools for fixing graphics accessibility issues.

Adding Alt Text to Existing Figures

1. Open your PDF in Adobe Acrobat Pro
2. Go to View > Show/Hide > Navigation Panes > Tags
3. In the Tags panel, expand the tag tree
4. Find the Figure tag for your image
5. Right-click the Figure tag and select Properties
6. Click the Tag tab
7. Enter your description in the Alternate Text field
8. Click Close

Tagging Untagged Images

1. Go to Tools > Accessibility > Reading Order
2. The Reading Order dialog appears, and content is highlighted
3. Draw a rectangle around the untagged image
4. Click the Figure button in the dialog
5. The image is now tagged as a Figure
6. Add alt text using the steps above

Marking Decorative Images as Artifacts

Images that are purely decorative (like borders, backgrounds, or design elements) should not be tagged as figures. Instead, mark them as artifacts so screen readers skip them.

1. In the Tags panel, find the Figure tag for the decorative image
2. Right-click and select Change Tag to Artifact
3. Select the artifact type (typically "Background" or "Layout")
4. Click OK

Using the Accessibility Checker

1. Go to Tools > Accessibility > Accessibility Check
2. Select PDF/UA-1 as the standard
3. Under checking options, ensure Alternate Text is selected
4. Click Start Checking
5. Review results and fix issues directly from the report

How to Fix in Microsoft Word

Fixing alt text at the source (in Word) before creating your PDF is more efficient and creates better results.

Adding Alt Text to Images in Word

1. Right-click on the image
2. Select Edit Alt Text (or Format Picture > Alt Text in older versions)
3. Enter a description in the alt text field
4. If the image is decorative, check Mark as decorative
5. The alt text will be preserved when you export to PDF

Best Practices for Word to PDF

1. Use File > Save As and select PDF format
2. Click Options before saving
3. Ensure Document structure tags for accessibility is checked
4. Ensure Create bookmarks using: Headings is selected if you have headings
5. Click OK and save

For Decorative Images

1. Right-click the image and select Edit Alt Text
2. Check the box for Mark as decorative
3. Word will export this as an artifact, not a figure

Testing Your Fix

After making corrections, verify your changes work correctly.

Quick Test in Acrobat

1. Go to Tools > Accessibility > Accessibility Check
2. Run a full check with PDF/UA-1 selected
3. Verify no "Figures alternate text" errors appear
4. Expand each Figure in the report to confirm alt text is present

Test with a Screen Reader

1. Open the PDF in a screen reader (NVDA, JAWS, or VoiceOver)
2. Navigate through the document
3. Listen to how each image is announced
4. Verify the alt text makes sense in context

Use PAC (PDF Accessibility Checker)

1. Download PAC from the PDF Association (free tool)
2. Open your PDF in PAC
3. Run the PDF/UA check
4. Review the "Matterhorn Protocol" section for Checkpoint 13 results
5. Address any remaining failures

Manual Review Checklist

• All meaningful images have Figure tags
• All Figure tags have appropriate alternative text
• Alt text describes content and purpose, not just "image of..."
• Decorative images are marked as artifacts
• Captions are tagged and associated with their figures
• Complex graphics have adequate descriptions or supplementary content

Additional Resources

Official Standards and Guidelines

• W3C WCAG 2.1 Success Criterion 1.1.1: Non-text Content
• PDF Association Matterhorn Protocol 1.02
• ISO 14289-1 (PDF/UA-1) Standard

Tutorials and Guides

• Adobe Acrobat Accessibility Documentation
• WebAIM: Alternative Text
• W3C WAI Images Tutorial

Tools

• PAC (PDF Accessibility Checker) - Free PDF/UA validation tool
• NVDA Screen Reader - Free screen reader for testing
• Adobe Acrobat Pro Accessibility Checker

This documentation is based on the Matterhorn Protocol 1.02, the definitive reference for PDF/UA validation. For the most current information, consult the PDF Association and W3C WCAG guidelines.