Making PDF Files Accessible.

Learn how to create accessible pdf files from scratch & also learn about the various online tools available to make your Acrobat documents accessible.

Introduction

History and Overview of PDF and Accessibility:

As the Internet has grown and developed in recent years, PDF (portable document format) has emerged as one of the most popular formats for posting documents to the World Wide Web. In large part this popularity rests upon the versatility of PDF documents.Fonts, formatting, colors, and graphics of any source document can be preserved in a PDF document irrespective of the operating platform and the application under which the file originally was created. In addition, many authors and publishers prefer converting materials to PDF for the security protections offered by this format. Unlike traditional documents that are read and produced by word processors, PDF files are loaded and viewed one page at a time. In other words, your computer loads each page individually, instead of the entire document as in traditional word processing programs.

For these reasons, PDF files have become perhaps the most extensively used formats for digitizing print-based materials. Like it or not, PDF documents will be an integral part of the Internet for the foreseeable future. With this in mind, learning to create accessible PDF files is a key component to the project of creating an accessible digital world.

Before the release of the various applications in the Acrobat 5.0 family, PDF files contained no real text, but were merely graphical renderings of a page. In addition to posing a variety of problems for disabled and non-disabled users alike, this made PDF documents impossible for people using screen-reading technologies to access any of the information contained within a PDF document. With the release of Acrobat Reader 5.0 in 2001, however, Adobe incorporated several accessibility features into their product, allowing users to read PDF files with screen readers, view documents in high contrast mode, zoom and resize text to fit any size view, and enabled basic keyboard navigation. These developments benefited a large sector of the disabled population. In addition several plug-in and features within the Acrobat Capture Pack made it possible to create accessible documents from scanned images. Moving print-based data from the hardcopy page into an accessible format via an optical character recognition function is a powerful tool, though a quick and accurate conversion remains dependent upon the clarity and layout of the hardcopy.

Most recently, the release of the suite of applications in the Acrobat 6.0 family has built upon the accessibility features first introduced two years ago with version 5.0.

Issues:

Despite the progress, however, many PDF documents on the internet remain inaccessible. The primary issues are,

  1. Many files published to the internet before the release of Acrobat 5.0 still remain inaccessible because they have not been updated. In order to be accessible, these older documents need to be tagged and marked up for accessibility.
  2. In an effort to create a visually accurate facsimile of the original document, publishers often create PDF files from scanned images. Such image-based PDF files contain no tags or marked text for screen readers to recognize, unless the image has been run through an optical character recognition (OCR) scan.
  3. Most PDF documents currently being placed on the internet were created with little attention to accessibility and are thus mostly inaccessible.

It is thus important to think about the best file format for your document at the very beginning.

Text-based PDF Documents:

If you are creating and writing a text document with a popular word processing program, converting the file to HTML or keeping it in the original word processor format is probably the most accessible option. Remember that it is almost always a good idea to offer different format options, e.g. providing, say, MS Word, Word Perfect, and PDF versions of your document. Of course, for the more intricate and complex documents, this will not be a feasible option, since fine-tuning each file would be more than a little labor-intensive.

Although PDF documents are not automatically accessible, there are some important strategies that can be implemented without a lot of extra effort. As with creating accessible HTML code, it is important to begin to think about accessibility at the outset of creating your document. Fortunately several advances have recently been made that promise a more universally accessible future for PDF document access. Perhaps the most notable improvement in Acrobat Reader (the free application available for download from Adobe.com), Adobe Standard, and Adobe Professional is the addition of an accessibility checker. This feature allows users to quickly check the degree to which any PDF file meets accessibility standards.

Image-based PDF Documents

Image-based PDF documents generated from a scan of a hardcopy or paper document are completely inaccessible for people using screen readers. These image-only files consist only a bit map of the image and thus have no searchable text.Updating such documents to meet accessibility standards requires scanning the image with OCR software and, depending on the complexity of the document, will require at least some editing. For those with resources to hire an outside organization to create an accessible, 508-compliant document, you can go to www.section508.gov and search in their database with the keyword "PDF" to see what companies offer PDF conversion. Additionally, if creating a PDF document from a TIF image, it is a good idea to keep this original file. TIF images are easily imported to OCR technologies and do not require Virtual Printer plugins and the like. In fact, some publishers have began offering documents in TIF as well as PDF formats. Although this kind of file mirroring has its shortcomings, it does eliminate same of the technological glitches often encountered by users who are trying to perform and OCR scan on a PDF document.

In order for a PDF document to be accessible it must contain real text and be tagged and marked up for accessibility. Nonetheless, there are some items which at this time simply cannot be rendered in an accessible form within a PDF file. If your document features any of the following characteristics or items, you may wish to use MS Word or HTML to display the information.

Software Packages:

The following list identifies the software packages that you will need for creating accessible PDF documents.

For converting image-only files so that they contain real text or for creating accessible PDF files from paper documents, you will need one of the following software packages.

Adobe Professional 6.0
OmniPro
Text Bridge

This list is not necessary a complete itemization of all available software, but it represents some of the more popular products. Note that the Center on Education and Work does not endorse any of these products.

Strategies and Methods for Making PDF Documents Accessible

What you will need to do to make your PDF document accessible will be determined by the source of your document. First we would look at Text based PDFs. If you are working with an image-only file and wish to convert it to an accessible PDF, you will find the next section "converting image only files to PDF" helpful.

Logically Structured Documents:

There is more to making PDF documents accessible than designing a visually pleasing document. You should first consider the logical structure of the file itself. If you are working with a large file, for example, you will want to create internal navigation links so browsers can move quickly to the section or chapter for which they are looking. Similarly, you will need to take full advantage of structural elements that identify sections, columns, and paragraphs. You will save yourself a great deal of time and effort if you avoid creating text-based tags within Adobe Acrobat's tag creator. If you are using Microsoft Word to create your document, here are a few hints for using structural elements which will go a long way in making an accessible document:

Convert a MS Word Document into a PDF file:

If you can avoid transferring a scanned image into Acrobat Reader, your task should be a more straightforward one. In other words, if your document was created by a popular word processor like MS Word or Word Perfect, the document can be made into an accessible PDF file quite easily, though the document's complexity can add additional steps to the process.

The next time you want to convert a document to PDF format, you only need to do the following:

Tags:

Check one's "tags" after the document has been converted. To view the "tag root," go under "Window" in Acrobat, and then go down to tags. This is available in version 5.0 only. It is important to make sure that any images are properly tagged. Tagging is a very difficult and precise task. To learn more about tagging, go to http://www.adobe.com/products/acrobat/access_booklet.html.

Duplication:

One alternative to spending a large amount of time and effort converting a complex PDF file into an accessible document is to post a duplicate copy of the file on your site in Microsoft Word or WordPerfect. This is especially the case when if the file was originally designed with popular MS Office applications like MS Word and Excel. These two popular applications can produce accessible documents if one takes full advantage of the structural elements while creating the file. When you post the PDF to your site, simply put an additional link near or adjacent to the PDF link. This will be especially helpful when attempting to make tables and charts accessible. For example, if you were to have an internal link (i.e., a link within the website) to a PDF document entitled "PDF duplicate example.pdf," you would merely type or cut and paste that title into another link to the respective format (PDF duplicate example.doc) and (PDF duplicate example.wpd). To increase the security settings on for the duplicated documents, you will want to save the files as "read only."

Adobe's Tools:

There are several tools available, both through Adobe Acrobat and other third parties, that can assist you in making your PDF documents accessible.

Using the Accessibility Checker in Acrobat :

Once you have run the accessibility checker, you will need to know how to interpret as well as correct the problems identified by the software. Keep in mind that you can adjust the level of detail the checker will flag for you.

Choose "Quick Check" for a brief report on your file's level of accessibility. Select "Full check" if you would like a more detailed report. (note that many of the problems flagged in this mode are often only "potential" problems).

Images and photos can be found by opening the Tags window. You may run across this error when using decorative borders, table graphics or underlined text. In such cases The alternate text might only say something like "ornamental border" or "line." If there are many such images, you may need to seek out the creator of the file to have the original document reworked.

Making Scanned Images Accessible

Increasingly libraries, archives, and an assortment of other public and private organizations have been making documents available through PDF or TIF image formatting. While more recent PDF files can be rendered accessible to screen readers with real text, much of the information now being archived on the Internet does not contain such text-based information. In order for visually impaired or blind users to access this data, it must first be run through an OCR (optical character recognition) scan of the image file. Such a scan will interpret the image, identifying any text within the image.

Many scanning programs like OmniPro and Text Bridge are designed especially to convert image-based files containing text to real text files. This technology, known as Optical character recognition(OCR) allows users to scan their images for legible text. Depending on the quality of the image and the original hardcopy document, the OCR function will identify any text contained within the image itself. If the document contains only simple formatting and is a crisp and clear image, the amount of editing should be minimal. If the original document is degraded or if the scanned image is of poor quality or even slightly skewed, a considerable amount of editing and rewriting may be necessary. This is why it is very important that the scanned image is of a high quality. For tips on scanning documents, see the brochure produced by the Center on Education and Work.

Web Resources:

The Web AIM tutorial for creating accessible PDF documents is one of the best on the Internet. Go to

http://www.webaim.org/howto/acrobat/)