Adobe Acrobat 5.0 Offers Improved
Accessibility for Screen Readers
One of the major concerns of organizations dealing with accessibility to electronic information for people with disabilities has been the inaccessibility of Adobe Portable Document Format (PDF) files. PDF is a popular format used for displaying documents, presentations, etc. on the Web. However, people with visual disabilities who depend on screen readers have found it difficult or impossible to access PDF files. Adobe Acrobat 5.0 now has features that make PDF files more accessible to screen readers.
Whether you are publishing a document in HTML, Adobe PDF, or some other format, creating accessible documents requires much more than simply representing the original document accurately. Sighted people can look at a printed page and easily determine what are titles, subtitles, columns of text, headers, footers, and so on. Visual clues, such as location of the text on the page, bold text, and large font sizes help to determine the structure of a document so that it can be easily read and navigated.
Unfortunately, assistive technologies such as screen readers are not able to depend on these visual clues. They rely instead on the underlying computer-based information to provide that same structure. Therefore, in order to be accessible, documents must be authored so that they contain not just content (such as the text in the document), but also information about the structure of the content (such as how the text flows within the page and from page to page).
Acrobat 5.0 works with Microsoft Office 2000 for Windows (Word, Excel, and PowerPoint) by capturing the logical structure information contained in the source document including titles, headings, Word styles, Excel table data, columns, bulleted lists, and so on. This information is saved in a tagged Adobe PDF file with the proper reading order. Alternate text (ALT tags) for images which authors define when creating their Office 2000 documents are also preserved.
What about PDF files which were created before the new features of Acrobat 5.0 were available? There is a free MakeAccessible plug-in for Acrobat 5.0 (Windows only) that allows the creation of tagged PDF files from untagged PDF files (e.g., PDF files made with Acrobat 4.0, or files that were not made in Microsoft Office 2000 applications). The plug-in automatically analyzes the logical structure of a document and creates a new version of the file that will read more clearly with a screen reader or other assistive technology device. The MakeAccessible plug-in can be downloaded from www.adobe.com/support/downloads/88de.htm.
Other enhancements available with Adobe Acrobat 5.0 include keyboard shortcuts, ability to show PDF files in high-contrast mode, ability to zoom in and reflow text on the screen, and the ability to export to Rich Text Format (RTF) so that the information can be reused in other programs. An Accessibility Checker points out common accessibility problems in PDF documents such as missing ALT tags for images, unspecified languages for text, and unrecognizable character encoding. There is an option to fix or ignore these problems before distributing the document. In addition, a Tags palette displays the logical structure of a tagged Adobe PDF file and can be used to correct problems found by the Accessibility Checker. The read order of a tagged document can be revised by adding or rearranging items in the list. Information can also be added to a document's structure to make the contents of the document fully accessible. For example, ALT tags can be added to images so screen readers can describe them in words.
Adobe also has a solution for scanned text documents that are displayed as bitmap images or PDF Image Only files. Screen readers are not able to recognize text within these types of documents where the text is displayed as an image. To overcome this problem, Adobe offers Acrobat Capture 3.0, which converts scanned image files into tagged Adobe PDF files. Capture 3.0 has the ability to search for, copy, and correct text. (Note: you need the Tag Adobe PDF agent in order to create a tagged PDF file with Acrobat Capture 3.0. This is a separately purchased plug-in available from Adobe).
Although very nice, these new features are by far a "cure-all". Problems are bound to pop up depending on the complexity of a PDF file. For example, the MakeAccessible plug-in and the Tag Adobe PDF agent may still experience problems with fonts, complex table recognition, complex layouts (e.g., paragraphs may be in the wrong order), and layers of objects within a complex PDF. Despite these problems, this is still a major step in the accessibility arena for Adobe Acrobat, with additional improvements expected in the future.
Visit these Adobe Acrobat Web sites for more information:
Adobe Acrobat 5.0:
Adobe Acrobat solutions for accessibility:
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©2001 University of Hawaii
Updated: November 21, 2001