Authoring for Accessibility
While it is not recommend soley using the Adobe Portable Document Format (PDF's) to deliver content on the Web, there are at times circumstances that require that content be provided in this format. Some of the reasons that PDF's should be used are for:
- maintaining the formatting and design of the document (Foot-noted, end--noted, or side-noted, since there is no way to mark up any of these structures in HTML.)
- to protect the original document from editing,
- to allow the printing and distribution of the document in its intended format.
These are valid reasons to use PDF's for electronic distribution. However, it is important to note that while the appearance of a PDF document may look like a readable document, it can be completely inaccessible to users who rely on assistive technologies. The appearance of headings and footers and blocks of text may undoubtedly make sense to a sighted individual who can discern the meaning of presentational styles of bold letters for headings and the appearance of bullets to create a list. However, if these documents were not developed with the appropriate use of headings, paragraphs, alt text for images and so on, the document can be inaccessible to users who rely on screen readers and other assistive technologies that interpret the literal formatting of content, not the intended formatting.
Two Options for Accessible PDF's
Option #1: Provide an alternative HTML version of the PDF document in addition to the PDF.
Option #2: Make the PDF file natively accessible, by creating a tagged PDF file with all of the appropriate accessible markup.
If you will be creating an HTML version of the PDF, it is ideal to copy the content from the source document (such as MS Word) and pasting the content in a text editor (i.e., Note pad or Word pad) to strip out any formatting. Then copy > paste this content into the Content Management System (CMS) for formatting and publication.
Format Your Content Correctly
No matter which file format or application you will be converting your documents to PDF from it is important to make sure these documents are properly formatted prior to making the conversion to PDF. This means using only one level heading 1 per page, use the appropriate number of level 2 headings and if necessary, Level 3 sub-headings. Make sure paragraphs are formatted as such and use ordered and unordered lists appropriately. If you will be using images, make sure you apply alt text to the images if they are integral to understanding your content.
Design With Your Users in Mind
When developing the content in your source document, it is important to bear in mind who your audience will be and to develop this content accordingly. This means developing your content for low-vision and no-vision users, users with cognitive impairments, motor-impairments, and users who may be deaf. To learn more about design considerations for these groups of users, visit the 'How do I design for Accessibility' page.
Tagging Your PDF Document
After formatting your source document appropriately and after developing your content with your audience in mind, you will convert your document to PDF. If you marked up your content appropriately, the document should have applied the necessary tags required for screen reader accessibility...but don't bet on it. You must check the PDF to ensure that the tags have been appropriated correctly and in the correct order by following the steps in the next paragraph.
If you are taking an existing PDF and making it accessible, you will undoubtedly need to follow the steps below (From Joe Clark's A List Apart article: Facts and Opinions about PDF Accessibility). Please note that different versions of Adobe Acrobat handle the creation and management of tags differently -so please refer to the Adobe Acrobat Accessibility page for instructions based upon your version of Adobe Acrobat.
- Open your PDF.
- The Description pane of the Document Properties screen (File menu) will tell you if the document is tagged or not.
- If it isn’t, dismiss that screen. Go to the Advanced menu and choose Accessibility > Add Tags to Document.
- Run a full accessibility check from that same menu.
- If the checker reports any problems, open the little-known Tags palette (View > Navigation Tabs > Tags). Use the disclosure triangles to step through your document’s new tag structure. You’re better off if you select Highlight Content from the palette’s Options menu, as Acrobat will then draw a hard-to-see border around the object whose tag you select.
To handle the most common problems:
- If Acrobat complains that your document lacks a language specification, find the topmost tag in your document (immediately within the self-referential Tags tag). Right- or Ctrl-click it and select Properties. Select a language from the pop-up menu in the Language field, or type your own two-letter language code.
- For images lacking a text equivalent, do something similar, except you have to manually locate the Figure element that lacks the text equivalent. Context-click the Figure, select Properties, and fill in Alternate Text (exactly like alt in HTML) or Actual Text (for a picture of text).
- (There is a semi-automated way to find all Figures without text equivalents. If you run Advanced > Accessibility > Full Check and select “alternate descriptions are provided,” Acrobat will find all the figures without text equivalents and provide you links to them in its report.)
- A document from a printed source may contain “artifacts” like headers and footers that you never want screen-reader users to hear. You can context-click on those items (which may be deemed Figure, Part, P, or something else) and Create Artifact, which will cause Acrobat and compliant screen readers to ignore them when voicing. (You can also use the Touch-Up Reading Order tool to select the artifact on the actual page and mark it as Background.)
Scanning PDF Documents for Accessibility
Adobe Accessibility Auto Checker
Adobe Acrobat Standard 6.0 and higher comes with a Quick Check feature. However, this is fairly basic and you will need to test one PDF document at a time.
PAC - PDF Accessibility Checker
Free PDF accessibility scanning tool recommended from W3C.
Free PDF accessibility checker.