Stop Global Warming

Website and PDF Accessibility

March 3, 2011

Overview

Making and keeping your website accessible to all visitors is important not only to meet Ontario's accessibility requirements but also ethically, to make information available to all site users regardless of disabilities they may have. Ontario's proposed standard is still in the draft stages of accessibility legislation. It's not clear when it will be passed into law. Unfortunately, the legislation isn't too clear and is actually contradictory in some cases. For the most part it states that sites should meet the World Wide Web Consortium (W3C) Web Content Accessibility Guidelines - level A standard initially but aim to achieve Level AA.

The Internet is filled with PDF documents. They are a convenient document format and have many appropriate uses (e.g. for complex layouts, long text documents, complex forms, etc). In these cases, they should be used, but otherwise, our first instinct should be to post content to the site as HTML. This will make it more accessible and also more easily findable using search engines.

Note, that accessibility in this context refers to making documents usable by site visitors using alternate screen readers – for visually impaired, hearing impaired, physically impaired, and cognitively impaired users. It's important to recognize that modern screen readers can handle PDFs but due to the complexity of PDFs, we may need to work harder to make them accessible.

This article discusses:


Making a Website Accessible

The process of making the site accessible consists of:

  1. Educating oneself about the accessibility requirements
  2. Running accessibility validators on the website pages to identify potential accessibility barriers. Updating site code until the errors are corrected. It's important to note here that online validators are automated tools which may miss some accessibility errors and falsely identify others. So even if a validator indicates the presence of problems, there may not actually be any. For this reason, it's important that a web developer familiar with the guidelines review the validator output.
  3. Finally, a manual pass of the site is made to identify issues that would be missed by the validators – e.g. logical page structure errors.

What Makes a PDF accessible?

A PDF is considered accessible if it has a logical structure that can be used to navigate and understand the document using a screen reader. This is achieved by tagging the elements of the document (headings, table headings, images). There is a predefined set of tags which will be sufficient for most purposes but additional tags can be defined.

Just like with web pages, it also means making reasonable choices – such as using text for text content and not embedding text into images. Where images are used, descriptive text should be used for those users who can not see them.

There are various accessibility standards – for our purposes, we'll be using the W3C's Web Content Accessibility Guidelines 2.0 with AA rating.


Making a website's PDFs accessible

To make the PDFs accessible, proceed as follows:

  1. PDFs currently on the site
    • Evaluate whether the PDF can be replaced with a webpage and if so, do so
    • With remaining PDFs, add a summary of the PDF on the web page that links to the PDF.
    • Consider offering the option for site users to request an alternate version of the document – e.g. Word document or Rich Text Format
    • Use the Acrobat Professional tools to analyze and correct basic issues.
    • Manually review the PDFs to detect major problems missed by the Acrobat Professional analysis (e.g. PDFs that are scans of text documents and don't contain any text that can be understood by screen readers )
    • Fix these issues if possible – may require going back to originator of document
  1. New PDFs to be added to the site (including updates of documents currently on the site)
    • Edit the source document (typically a Word file) to make it accessible and then generate the PDF from that using the steps described previously. This will reduce the amount of work required for future updates.

If time/budget is limited, I recommend:

  1. Add summary text on pages that link to PDFs
  2. Fix the worst offenders and most popular PDFs (either by replacing with web pages or fixing the PDFs)
  3. Make sure that all new PDFs added to the site are accessible
  4. Add a note offering alternate versions of PDFs on request.

This can avoid the cost of processing all of the PDFs – some of which get fairly minimal traffic.


Appendix: Technical notes on how to make PDFs accessible

1. How to make new PDFs accessible?

  1. Most PDFs are created in authoring software (like a word processor) and exported to PDF using an Adobe plug-in (like Adobe PDFMaker). The best place to start then is by using applications that support the production of tagged PDFs – such as recent versions of Microsoft Word and Open Office.
  2. Apply document styles (e.g. 'Heading' or 'Text body'). This will translate into a logically tagged PDF. Avoid formatting text with other tools (e.g. by changing font size or font type) – because in that case, no style is applied to the text. For example, you might bump up the font size on some text and intend it to be a header. Without applying the 'header' style to it, the word processor does not know what you intend and cannot apply the header tag to the text. For sighted users, visually scanning a text document, your formatting choice is clear but blind and other users rely on the headers being read to them and use those headers to navigate the document. Your header would be invisible to those users.
  3. Then we need to enable the output of 'tags' in the exported PDF. This varies by application.
  4. Now, open the document in Adobe Acrobat Professional (this is different from the free Adobe Reader) to use the following tools:
    • Accessibility checking
    • Structural editing to add/modify tags and to add/modify descriptive text
  5. Within Acrobat Professional, check the PDF for compliance with accessibility guidelines. From the 'Advanced' menu, select 'Accessibility', and then 'Full Check'. This will give a list of issues and how to resolve them.
  6. Unfortunately, you still need to manually review the document to make it sure it complies with accessibility standards. There is no fully automated solution for this. Tools that can assist with this in Acrobat Professional include:
    • Reflow – to check reading order
    • Read Out Load – To hear what a user would hear using text-to-speech conversion

2. How to make existing PDFs accessible?

  1. Open the PDF in Adobe Acrobat Professional, and run the Accessibility check as described above.
  2. Make the recommended changes.
  3. Do a manual inspection of the document to ensure compliance with accessibility standards.
Additional reading:

PDF Accessibility
This article gives an excellent overview of PDFs, describes in detail how to use Word to create tagged PDFs, and how to use the tools within Acrobat Professional.

Facts and Opinions About PDF Accessibility
An overview of the issues and technologies involved.

Adobe® Acrobat® 9 Pro Accessibility Guide: Creating Accessible PDF from Microsoft® Word
How to use Word to make tagged PDFs.

Adobe® Acrobat® 9 Pro Accessibility Guide: Using the Accessibility Checker
Detailed instructions on using Adobe Acrobat for checking accessibility and modifying PDFs to pass validation.

Back to essays

HOME SCREENWRITING VIDEO MULTIMEDIA GAMES PHOTOGRAPHY CONTACT LOGIN ESSAYS