Adobe PDFs include various accessibility features to ensure they are usable by individuals with disabilities.
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Content Creation Features
The instructions below are for Adobe Acrobat Pro, one of the most widely used tools for adding accessibility features to PDFs.
Alt Text for Images
Adding alternate text (alt text) to PDFs is essential for making documents accessible to people who use screen readers or other assistive technologies. Alt text provides descriptions of images, charts, and other non-text elements, enabling visually impaired users to understand the content's meaning.
Open the PDF in Adobe Acrobat Pro.
Go to Tools > Accessibility
Select Set Alternate Text.
A dialog box will appear showing all the images in the document.
Add descriptions for each image or mark it as decorative if it doesn't convey essential information.
Save the document.
Tagged PDFs
Tagging a PDF document is essential for making it accessible to users who rely on assistive technologies like screen readers. Tags define the structure and order of the content, enabling assistive tools to interpret and present the information correctly.
What Are Tags in a PDF?
Tags provide a logical structure to the document, identifying elements like headings, paragraphs, lists, tables, images, and links. They are similar to HTML tags in a webpage.
Open the PDF:
Launch Adobe Acrobat Pro DC and open the document you want to tag.
Check for Existing Tags:
Go to View > Show/Hide > Navigation Panes > Tags.
The Tags pane will appear on the left. If it's empty, the document is not tagged.
Add Tags Automatically:
Select Accessibility > Autotag Document from the Tools menu.
Acrobat will attempt to tag the document automatically.
Manually Add or Edit Tags:
In the Tags pane, right-click and choose New Tag to create a new tag (e.g., Heading, Paragraph, Figure).
Drag and drop content into the appropriate tag.
Right-click on images and add alternate text under Properties.
Check Reading Order:
Open Accessibility > Reading Order.
Review and adjust the order of elements to ensure they are logical.
Run an Accessibility Check:
Go to Tools > Accessibility > Full Check.
Acrobat will generate a report highlighting accessibility issues, including tagging errors.
Best Practices for Tagging PDFs
Ensure a logical reading order for assistive technologies by using a proper tagging structure.
Use nested tags to maintain hierarchy, such as <H1> for main headings and <H2> for subheadings.
Maintain a correct document structure, including headings, paragraphs, lists, and tables.
Readable Text
Readable text in a PDF refers to text that can be selected, searched, and interpreted by assistive technologies such as screen readers. It contrasts with "non-readable" text, such as scanned images of text, which appear as images and lack an underlying text layer. Readable text is crucial for accessibility, usability and compliance with accessibility standards.
Create PDFs from Text-Based Files
Use software like Microsoft Word, Google Docs, or other text editors to create your document.
Export the document to PDF while preserving the text layer:
In Word, use File > Save As or Export > Create PDF/XPS Document, ensuring accessibility features are enabled.
Use Optical Character Recognition (OCR)
For scanned or image-based PDFs, apply OCR to convert the images into readable text.
Steps in Adobe Acrobat Pro DC:
Open the scanned PDF in Acrobat Pro.
Go to Tools > Scan & OCR.
Click Recognize Text > In This File.
Save the document after OCR processing is complete.
Free OCR Tools:
Online tools like SmallPDF, Adobe Scan, or Google Drive OCR.
Check Text Accessibility
Use Accessibility Checker in Adobe Acrobat Pro:
Go to Tools > Accessibility > Full Check to identify and resolve issues with readable text.
Test with a screen reader to ensure all text is accessible.
Avoid Common Issues
Do not use images for text unless necessary. If used, provide alternate text or captions.
Ensure embedded fonts are properly included in the PDF to prevent text from becoming unreadable.
Tips for Creating Readable PDFs
Export from Accessible Sources:
Use text-based file formats and ensure proper formatting (e.g., headings, lists, alt text for images) before conversion.
Use Tagged PDFs:
Tagged PDFs provide a structured layout, improving navigation and readability.
Verify and Test:
Regularly check documents with screen readers or accessibility tools to confirm their readability.
Testing for Readable Text
To check if a PDF has readable text:
Select Text: Try highlighting the text in the PDF. If it's selectable, it’s readable.
Search Functionality: Use the search feature in your PDF reader. If it works, the text is readable.
Screen Reader: Test with a screen reader to confirm accessibility.
Form Accessibility
Creating accessible PDF forms ensures that individuals with disabilities can interact with and complete the forms using assistive technologies like screen readers, keyboards, and other input devices. An accessible PDF form allows all users to navigate fields, understand instructions, and submit the form successfully.
Key Features of an Accessible PDF Form
Logical Reading Order: The content and fields must follow a logical sequence to ensure that assistive technologies can interpret and read the form correctly.
Interactive Form Fields: Use fillable fields (text boxes, radio buttons, checkboxes) instead of static text or images for user input.
Labels and Instructions: Provide clear labels and instructions for each field. Use tooltips or alternate text to describe the purpose of fields.
Keyboard Navigation: Ensure users can navigate between form fields using the keyboard (e.g., Tab key).
Screen Reader Compatibility: Form fields should include meaningful names and descriptions to help screen readers identify their purpose.
High Contrast and Readable Fonts: Use high-contrast colors and legible fonts for all text, labels, and instructions.
Error Identification: Provide clear instructions or feedback for required fields or invalid entries.
Steps to Create an Accessible PDF Form
Convert to a Fillable Form:
Open your PDF in Acrobat Pro.
Go to Tools > Prepare Form and let Acrobat detect form fields automatically, or manually add fields.
Add Field Descriptions:
Right-click on a form field, select Properties, and add a meaningful description under the Tooltip section.
This description helps screen readers convey the field’s purpose.
Set Tab Order:
Ensure the tab order follows the logical reading order.
Open the Page Thumbnails pane, right-click a page, and select Page Properties > Tab Order.
Use the Accessibility Checker:
Go to Tools > Accessibility > Full Check to identify and fix accessibility issues in the form.
Add Clear Instructions:
Include instructions for filling out the form at the beginning.
Start with an Accessible Source Document
If the form is designed in Word or another program, follow these guidelines before converting to PDF:
Use proper headings, labels, and form field names.
Add alt text for images or icons.
Ensure logical reading and navigation order.
When saving to PDF:
Use the Save As option and check Document structure tags for accessibility to preserve accessibility features.
Test with Assistive Technologies
After creating the form, test it with screen readers (e.g., NVDA, JAWS) and keyboard navigation to ensure:
Fields are announced correctly.
Navigation flows logically.
Instructions are clear.
Best Practices for Accessible PDF Forms
Avoid Static Form Fields: Ensure all fields are interactive and properly tagged.
Use Sufficient Field Sizes: Ensure text fields are large enough to accommodate input.
Provide Alternate Formats: Offer alternative formats (e.g., Word documents) for users who may have difficulty with PDFs.
Add Submit and Reset Buttons: Include buttons with clear labels for submitting or resetting the form.
Compliance and Standards
Accessible PDF forms should comply with:
WCAG (Web Content Accessibility Guidelines).
PDF/UA (Universal Accessibility).
Section 508 (U.S. accessibility law).
Testing Tools for PDF Form Accessibility
Adobe Acrobat Accessibility Checker: Built-in tool to identify accessibility issues.
PAC (PDF Accessibility Checker): Free tool for evaluating PDF/UA compliance.
Assistive Technologies: Test forms with screen readers and keyboard-only navigation.
Accessibility Checker
The Accessibility Checker in Acrobat Pro scans PDFs for potential accessibility issues and provides guidance on fixing them. However, it will only alert you to errors detectable by a computer, like missing alt-text, and is not able to accurately assess things like the accuracy or usability of the alt-text, or errors in the page reading order.
User Features
Keyboard Navigation
Keyboard navigation is a critical feature for making PDFs accessible, especially for users who cannot use a mouse due to mobility or vision impairments. It allows users to navigate and interact with the content, such as reading text, filling out forms, and activating links, using only the keyboard or assistive technologies.
Ensure Logical Tab Order
In Adobe Acrobat Pro DC:
Open the PDF and go to Tools > Prepare Form.
Select Fields and click Tab Order in the right-hand panel.
Choose Order Tabs by Structure to follow the logical reading order or manually adjust by dragging fields into the correct sequence.
Use Accessible Tags
Check for tags in Adobe Acrobat Pro:
Go to View > Show/Hide > Navigation Panes > Tags.
Ensure all elements, like headings, paragraphs, lists, and images, are properly tagged.
If the document lacks tags, use Tools > Accessibility > Autotag Document.
Test with Keyboard Navigation
Open the PDF in a viewer like Adobe Acrobat Reader or another accessible PDF viewer.
Use these keys to test navigation:
Tab: Move to the next interactive element (e.g., link, button, or field).
Shift + Tab: Move to the previous interactive element.
Enter: Activate a link or button.
Arrow keys: Scroll through the document or move within text.
Add Navigation Features
Bookmarks:
Create bookmarks to allow users to jump to specific sections.
In Acrobat Pro, go to Tools > Organize Pages > Add Bookmark.
Headings:
Use tagged headings for structured navigation.
Hyperlinks:
Ensure links are clearly labeled and keyboard-accessible.
Testing Tools for Keyboard Navigation
Adobe Acrobat Accessibility Checker:
Automatically identifies navigation issues.
PDF Accessibility Checker (PAC 2021):
Verifies compliance with PDF/UA standards.
Screen Readers:
Test navigation using tools like NVDA, JAWS, or VoiceOver.
By implementing and testing keyboard navigation, you ensure your PDF is inclusive and accessible to all users, including those relying on keyboards or assistive technologies.
High-Contrast Mode
High contrast mode is an accessibility feature designed to improve readability for individuals with visual impairments or color blindness. In PDFs, high contrast mode adjusts the colors of text, background, and other elements to ensure sufficient contrast, making content easier to read. Users can enable high contrast through their operating system, PDF viewer or both.
Benefits of high-contrast mode.
Improved readability: Enhances text visibility by increasing contrast between text and background.
Reduced eye strain: Easier to read for long periods, especially for users with visual impairments or color sensitivity.
Adaptable for various needs: Customizable color schemes cater to specific vision conditions.
Adobe Acrobat Reader DC
Adobe Acrobat Reader supports high contrast settings directly.
Steps to Enable High Contrast in Adobe Acrobat Reader:
Open Adobe Acrobat Reader.
Go to Edit > Preferences (Windows) or Acrobat Reader > Preferences (Mac).
Select Accessibility from the list on the left.
Under Document Colors Options, check Replace Document Colors.
Choose from the predefined high contrast color combinations:
Black text on a white background.
White text on a black background.
Yellow text on a black background.
Custom color options (set your preferred text and background colors).
Click OK to apply the changes.
Browser-Based PDF Viewers
If you're viewing PDFs in browsers (like Chrome, Edge, or Firefox), enable high contrast mode in your operating system.
Windows:
Open Settings > Ease of Access > High Contrast.
Toggle Turn on high contrast and choose a color theme.
macOS:
Open System Preferences > Accessibility > Display.
Enable Increase Contrast or Invert Colors.
High contrast settings in your OS will apply to the browser-based PDF viewer.
Other PDF Viewers
Many alternative PDF readers also support high contrast modes. Check the Preferences or Accessibility settings to find similar options.