Making non-accessible PDFs accessible

Most non-accessible PDF documents can be made accessible to screen reader users by tagging its contents using Adobe Acrobat Pro .

FYI for ALA staff: Adobe Acrobat Pro 9 is available for use in the ITTS training room.

However, before you can create a tagged PDF, you must make sure that the PDF contains real text and is not just a series of scanned images. To do so, try to highlight text in the PDF with your cursor. If you are able to highlight text with a text cursor, then it is not scanned. If you are only able to draw boxes with a crosshair cursor, then the document is likely one big scanned image.

Convert scanned PDFs to text
If the PDF is scanned, you must convert it to text before it can be tagged. To do so:
  1. Go to Document > OCR Text Recognition > Recognize Text Using OCR.
  2. In the Recognize Text dialog box, make sure that All Pages is selected and that the Searchable Image output option appears under Settings.
  3. Click OK.

Add tags to PDFs

The Tags Panel allows you to view and edit tags in the PDF’s tag tree structure. Tags are listed in a hierarchical order that indicates the reading sequence of the document, and they appear as coded element types in angle brackets.
Each element appears in the tree structure by type, title, and the element’s content or a description of the content. To add a tag tree structure to a PDF:
  1. Go to View > Navigation Panels > Tags to open the Tags panel.
  2. Drag the panel to the sidebar, or go to View > Navigation Panels > Dock all Panels.
  3. In the Tags panel, go to Options > Highlight Content.
  4. For untagged documents, go to Advanced > Accessibility > Add Tags to Document. This will automatically tag document elements with generic (mostly <P>) tags. You must still:
    1. Correct the element type and hierarchy using the Tags panel. See Adobe tag tree element reference for a tag tree structure example.
      1. To change the element type, right-click on the tag and select Properties.
      2. In the Tag window, select the correct tag type using the pull-down menu. Add Title text to provide additional labeling for navigation. (This is especially useful for complex tag tree structures.)
    2. Delete all elements with empty content boxes. These should not have been tagged.
      1. To delete an element or content box, right-click on it and select Delete Tag.
    3. Combine within one element all content boxes that belong together (e.g. heading text that appears in the document on three separate lines).
  5. To move an element or content box, left-click on it and move it to the appropriate location within the tree structure.
  6. To add new tags (you will likely need to add container elements), go to Tags > Options > New tag…
  7. Use the pull-down menu to select the tag type. Click OK.
  8. In the Tags panel, left-click on the new tag to drag it to the appropriate place in the tree structure.
  9. Click the + to expand the tag structure, then left-click and drag any subordinate tags into the tree below the higher level tag.
Note: While all tags must be properly applied according to their semantic roles, there is usually more than one correct way to mark up a document.

Sequence tags for reading order

The Order panel presents a sequential, numbered list of both the document’s pages and the elements within each page. This list reflects the order in which a screen reader will read content. All order changes made in this panel will be reflected in the Tags panel as well.
  1. Once you’re done adding tags, go to View > Navigation Panels > Order to open the Order panel.
  2. In the Order panel, double-check that all tagged content is presented in the proper reading order. To rearrange tagged content, left-click and drag the content icon within the panel.
  3. Repeat until you are satisfied with the reading order.

Add alternative (alt) text to images

Images in PDFs, like those on Web pages, must have alternate text to make them accessible to screen readers.
  1. To add alternative text to images (not including icons or graphic design elements), right-click on the <Figure> tag and select Properties...
  2. Enter the alternate text in the Alternate Text box, and click Close. Repeat for all images.
  3. If a given image has not been tagged, go to Tools > Advanced Editing > TouchUp Reading Order Tool.
  4. Draw a rectangle around the image.
  5. Click the Figure/Caption button. Click Close.
  6. To remove tags from icons or graphic design elements that do not require alternate text, go to Tools > Advanced Editing > TouchUp Reading Order Tool.
  7. Left-click on the numbered box to select it. Then right-click it and select Delete Selected Item Structure. Repeat for all erroneously tagged items in the document.

Properly tag an existing table

Data tables, like those on Web pages, must have tagged header cells and header cell scope specification to be optimally accessible.
  1. Go to Tools > Advanced Editing > TouchUp Reading Order Tool.
  2. If the table has not yet been tagged (otherwise skip this step): Draw a rectangle around the data and header cells of the table. Click the Table button. Click Close.
  3. Right-click on the table, and select Table Editor. All table cells will be highlighted gray (data cell type) or red (header cell type).
  4. If any cells have been improperly typed, right-click on the cell and select Table Cell Properties…. Select the correct radio button (Header Cell or Data Cell) under Type. Click OK.
  5. Right-click on each red header cell and select Table Cell Properties…
  6. Use the Scope pull-down menu to select the header cell’s related data cell groups (Row, Column, or Both). Repeat for all header cells.

Note: Never use spanned headers (i.e. two or more stacked rows or columns of header cells) in tables because screen readers have difficulty correctly conveying their content to users.

Additional resources

Adobe Acrobat 9 Pro Accessibility Guide: Best Practices for Accessibility: An extensive reference guide by Adobe for making PDFs accessible using Acrobat Pro 9 software.

Illinois Center for Information Technology and Web Accessibility: Web accessibility software resources and best practices guidelines from the Disability Resources and Educational Services (DRES) in the College of Applied Health Sciences at the University of Illinois at Urbana-Champaign.

Illinois IT Accessibility Initiative: ITaccess: Effort by the University of Illinois at Urbana Champaign to improve campus information technology accessibility by providing hands-on resources, tools, and training to identify and address issues relating to electronic information accessibility.

National Center on Disability and Access to Education: A set of fact sheets detailing accessibility problems and workarounds in various software programs commonly used to deliver distance education by the NCDAE. Comprehensive resources from the federal government for Web designers to learn how to make websites more useable, useful, and accessible. Includes instructions for planning usable sites, developing prototypes, and conducting usability tests.

WebAIM: Web Accessibility in Mind: An expansive collection of articles and instructional guides for making electronic information accessible. Maintained by a non-profit organization within the Center for Persons with Disabilities at Utah State University.