Evaluating PDFs for Accessibility

Adobe has a built-in Accessibility Checker to help users identify accessibility issues within a document. The automatic checker is a good starting point to assess the accessibility of the document, but it does not catch every issue. Some manual checks are also required.

Launching the Accessibility Checker

1. When the document is loaded, launch the Accessibility Check option. If it is not listed in the applications pane on the right, search for it (“Accessibility”) and then choose it from the results.
2. Keep the default Accessibility Checker Options that will appear in a dialog and click Start Checking.
3. The results will appear in the report in the left-hand panel. They will also be saved to your computer. This may be useful to share with the document creator in case they can address the issues in the source document.

PAC 2024 is a free accessibility checker that can check some WCAG requirements and can identify issues that are missed by the Adobe Accessibility Checker. For this reason, when testing PDFs, its encouraged to run both checkers and remediate issues. PAC is only available for Windows, so an alternative for MAC users is under review.

• Some of the highlights of PAC include:
  • Locating the title and language
  • Viewing the logical structure (tags)
  • Providing a screen reader preview
  • Identifying quality checks to help find accessibility issues
• Download PAC 2024
• Only available for Windows
• View the PAC 2024 Quick Start guide 

Title

The title describes the topic or purpose of the document. 

• In Acrobat, go to File > Properties > Title

Language

The default language of each page, passage, or phrase can be programmatically determined. 

• Check to see if the default language is set to match the document by navigating to File > Properties > Advanced Tab > Reading Options section, Language field.
• Also check to see if passages in another language match: Tags Pane > Select the tag of the foreign language text in the document > Right click > Properties > Tag tab > Language field

Headings

The document has a logical structure using properly implemented headings and the headings describe the section’s topic or purpose.

• Review the structure in Acrobat to ensure headings are logically nested in the Tags panel.
• Ensure that the heading text describes the topic or purpose of the content beneath it. 

Bookmarks

Documents with headings can be navigated using PDF bookmarks. 

• In Acrobat, go to View > Show/Hide > Navigation Panes > Bookmarks
• Verify that each heading is referenced in a Bookmark and the Bookmarks share the same hierarchy and order as the headings. 

Table of Contents

Long documents have a table of contents to help users navigate the document. 

• Review the logical structure in Acrobat in the Tags panel.
• Ensure that the Table of Contents is contained within a <TOC> element and each entry within the Table of Contents is within a <TOCI> element.
• Ensure that the links in each <TOCI> is in a <Reference> element.

Meaningful images have alternative text and decorative images are hidden from screen readers. 

• In PAC 2024, open the screen reader preview (eyeball button) and ensure that every image that is meaningful is contained within a <Figure> element and has an <Alt> element below it that accurately describes the image’s topic or purpose.
• If the image is used for style or decoration and does not have any meaning, ensure that the image is marked as an artifact:

  • In Acrobat, go to the Tags pane and click on the Options button  

    
  • Select “Find”
  • In the “Find” field, choose “Artifacts”
  • Choose “Search Document”
  • Navigate through each artifact using the “Find” button and verify that the decorative image is one of them.
• If the image is too complex to describe in 140 characters or fewer (graphs, charts, diagrams, etc.), the description needs to be presented in the document, as close to the image as possible. See the University of Washington’s guidance on complex images. 

Images of Text

Real text is used instead of images of text. 

• In Acrobat, select all text (Ctrl + A)
• Look to see if any text is not highlighted. Text that is not highlighted is likely an image of text.
• Unless the image is a logo, cannot be reproduced in text, or is otherwise essential, it needs to be replaced with real text. This cannot be done in Acrobat; the original source document will need to be edited. 

 All content is in the tag tree or marked as “artifact” if decorative.  

• In the tag pane, click on the Options Menu (three dots) and select “Find”. From the drop-down menu, select “Unmarked Content”, select “Search Document”, select “Find”.  

 Tables have logical structure.

• Open the Reading Order tool (Tools > Accessibility > Reading Order)
• Click on the Table or select it in the Order panel.
• Click “Table Editor”
• Verify that the cells that serve as table headers are table header cells using one of the following methods:
  • See if the header cells are highlighted in red and data cells highlighted in gray.
  • Right click on each header cell and choose “Table Cell Properties,” then verify that “Type” is “Header Cell”
• Verify that the headers are scoped according to the type of header it is – “Column” (data displayed top-to-bottom), “Row” (data displayed left-to-right), or “Both” (both a column header and row header).
  • Right click on each header cell and choose “Table Cell Properties,” then verify that “Scope” is set properly.
• Alternatively, if you are able to navigate the document using NVDA, it is quicker and easier to test tables using the table navigation. Navigate to each data cell and verify that the headers associated with that cell are announced.
• If the table spans multiple pages, verify that the table is contained within one <Table> element and not separate <Table> elements on each page.
• If the table is meant for layout, change its tag to a generic element, such as <Sect> or <Div>. 

 The purpose of each link can be determined from the link text.

• Review the display text to ensure the hyperlinks have a clear and accurate description of the link destination. Avoid using “click here,” "read more," or “link.”

Form Elements

Form elements have understandable labels and tooltips.

• Look at the text adjacent to each form field and verify that that text describes the purpose of the form field. This includes indicating if a form field is required or the data collected needs to be in a specific format.
• Then go to Tools > Prepare Form.
• Right click on each form field and click “Properties.”
• Verify that the tooltip field describes the purpose of the form field and includes any instructions needed for filling it out (reminder: screen reader users will not typically know of text instructions near form fields).
• Verify that the visual text adjacent to the form field is included in the tooltip.

Form Input and Errors

Form inputs do not cause unexpected behavior and validation messages tell users how to correct errors.

• Fill out each form field.
• Verify that no unexpected behavior happens (like launching a website). Error messages appearing in a window is expected behavior.
• Verify that if there is a validation error, the error message instructs the user on how to fix the error. 

 Tab order is logical and intuitive.

• In Acrobat, click into the document pane (or press F5).
• Press the tab key and navigate through each link, button, and form field in the document.
• Verify that each of these receives keyboard focus (a faint box will display around the element).
• Verify that the order in which they receive focus is logical and intuitive. 

When enlarging text, content can be viewed without loss of information or functionality. This is referred to as reflow, or the visual stacking order of the content. 

• Open the Order Pane from the right-hand tool menu.
• All content will be numbered. Visually inspect the numbered items to see if they make logical sense.  
• As a secondary check Adobe offers a “reflow” view. Navigate to Menu > View > Zoom > Reflow. Check to see if any content is out of order or if content disappears.   

 The order of the content is organized in a manner that preserves meaning and operability. 

• Screen readers will typically read the content according to the tag order, so it’s important to ensure the tag order is correct and logical.
• Open the Tag Pane from the right-hand tool menu.
• Navigate down through the tags and verify that the tags are in the same order as the elements are visually on the page.  

 Do not rely on color alone to convey meaning.

• Do a visual check for situations like these, which show examples of the incorrect and correct use of color to convey meaning

Text Contrast

Ensure appropriate color contrast so that content can be read by people with visual impairments. 

• Visually inspect the text/background combinations, including images of text (except for logos, photographs, or where the text is incidental).  
• If any look suspiciously low contrast, use the Colour Contrast Analyser or one of the evaluation methods suggested by WebAIM to verify whether the ratio meets WCAG 2.1 AA standards.
  • 3:1 for 18-point font (14-point bold) or above.
  • 4.5:1 for below 18-point font (14-point bold).
• Editing text contrast cannot be done in Acrobat; the original source document will need to be edited. 

Graphical Contrast

Ensure appropriate color contrast of graphical elements so their meaning can be understood by people with visual impairments. 

• The portions of graphics that are used to convey information (such as lines and bars on graphs, slices of a pie chart, and icons) have at least a 3:1 contrast ratio between itself and the background color.
• Logos, flags, pictures of real-life scenes, and graphics that represent other things (such as screenshots and biological schematic diagrams) are excluded from this requirement.
• Use the Colour Contrast Analyser to verify.
• See the Graphical Objects section of the WAI Understanding Non-Text Contrast page for examples.
• Editing graphical contrast cannot be done in Acrobat; the original source document will need to be edited. 

Do not rely on visual or auditory cues alone to communicate instructions for use or understanding. 

• Ensure that there is a text alternative that identifies elements referenced in instructions when those instructions rely on someone’s ability to see a component’s shape, size, or position, or hear a sound. 

 Lists are programmatically defined. 

• Look for text in the document that looks like it belongs in a list (items with bullets, numbers, or sequentially listed on new lines).
• In the tags panel, verify that these are grouped within an <L> element.
• Verify that each list item is contained within a <LI> element.
• Verify that each <LI> element has a <LBody> that contains the text and a <Lbl> that contains the bullet or number (if one exists).
• In the list spans multiple pages, verify that it is contained within one <L> element and not a <L> element on each page. 

• Verify that no content flashes or blinks. 
• Do not use embedded video or audio. Video and audio content cannot be implemented accessibly in PDFs.