To create an accessible PDF, you will need the full version of Adobe Acrobat. Acrobat has a built in "accessibility checker" that will guide you through some of the things that you will need to add to your document to produce an accessible PDF.
Accessible PDFs have tags added to the document. These tags provide the structure of the document. While users do not interact with the tags directly, assistive technology uses the tags for navigation. The PDF tags are similar, though not identical to, HTML tags.
When creating a document, the default view of a PDF within Acrobat does not show the tags. To show the tags tool, go to the view menu, then select show/hide, navigation panes, then select tags.
The most efficient and effective method of generating these tags actually starts with your source document. When creating a PDF out of a Microsoft Word (MS Word) document that is appropriately using styles such as headings and paragraphs, these styles will convert to the tags we need in the PDF document. If your document contains forms or tables, you will need to do additional work within Acrobat to make these accessible in the PDF.
The Action Wizard in the most recent version of Acrobat XI can guide you through some of the steps to make your PDF accessible.
Why use tags?
- Tags provide alternative text for images.
- Tags provide table markup such as headings.
- Tags provide heading and other structure of the document to aid in locating and navigating to content easily.
- Tags provide notice of language changes of text in document. Assistive technology will then speak the marked up text as appropriate for that language.
- Tags provide the order of the form fields when tabbing through a document (works with the Reading Order tool).
Outline of steps
- Optimize the source document for accessibility; for example, by providing sufficient color contrast between text and background and using semantic features like headings to identify sections instead of big, bold text.
- Save the file as a tagged PDF.
- Provide metadata for the PDF, such as the document language.
- Create and edit tags (similar to HTML tags) to give structural meaning to the document and allow navigation with assistive technology.
- Ensure that the reading order - how the content is presented to screen reader users - is logical.
- Ensure that the tab order (when the PDF has form fields or links) is sequentially correct.
- Check the PDF with automated and manual testing to ensure accessibility.
Accessibility in PDF documents ideally starts with the source document, preferably an MS Word document. For many tags, it is easier to put accessibility into the source document instead of trying to manually add them to the exported PDF. In particular, use the styles to designate headings and changes in text instead of manually changing font size and formatting. Avoid putting in empty line breaks as this will create unnecessary content in the PDF; if needed change the style to add spacing after paragraphs. When possible, use simple tables of one row and/or one column heading, as more complex tables will require more work with the tags in the exported PDF.
If you have a PDF generated from a scan of a hard copy, a lot of work will be required to convert this to text that is compatible with assistive technology. It is a better use of time to locate a digital copy of the original source and convert that than to attempt an Optical Character Recognition on a scan of a hard copy document. If you need to work with a scanned PDF, you will need to run the Optical Character Recognition tool and ensure the converted text is accurate.
Note on Google Docs: "printing" to a PDF from a google doc does not produce a tagged PDF document. To create a tagged document from a Google Doc, export to a MS Word document format first, and then fix styles and alt text as appropriate. Then follow the steps to export to a tagged PDF.
How you convert the document matters. There are several different ways to generate pdfs from word documents. The one that best preserves the accessibility features is to use the Acrobat add-in installed into MS Word when you install Adobe Acrobat. When you export, you may need to select an option to produce an accessible tagged PDF. Other processes such as choosing "print to PDF" from the print menu option may not preserve the tags necessary for your PDF to be accessible, causing additional work to remediate the document.
Using the accessibility checker
The accessibility checker in the full version of Adobe Acrobat will check for the required elements of an accessible PDF. It will generate a report of which elements pass and fail. It checks things like a document title, a document language, as well as the existence of tags for the content in the document and the reading order of the document. Once you have a tagged PDF, run the accessibility check as a reminder of the other features you need in your PDF. Change the initial view to show the document title instead of the file name; assistive technology will read the window title when the document opens.
For documents that include tables, you should make sure the original tables are simple tables- one column heading and/or one row heading. After you convert, you will manually need to change the tags to identify cells as header cells.
Resources for making accessible PDF documents