APH Web Features
Accessibility and Adobe PDF
Adobe Portable Document Format (PDF) is a universal file format that preserves all the fonts, formatting, colors, and graphics of any document, regardless of the application and platform used to create it. Adobe Acrobat 5.0 software converts any document to Adobe PDF files, even documents that have been scanned. Adobe PDF is a common file found on the World Wide Web. It is also used to distribute electronic documents over corporate networks, via e-mail, hard disks or CD-ROM.
Since Adobe PDF can represent documents that contain graphics, columns, vertical labels or other complex layouts, screen reading software for the blind may not be able to correctly reproduce some of these documents. However, Adobe studied the W3C guidelines for accessibility and Adobe Acrobat and Acrobat Reader 5.0 include a number of tools and features that help make information in Adobe PDF files accessible to the visually impaired. These include the following:
- Microsoft Active Accessibility. MSAA is a programming interface that allows Windows-based programs to present information about their content and its structure to assistive technologies, such as a screen readers with speech or with braille displays.
- Tagged Adobe PDF. This is a new feature that incorporates definitions of the document's structure into the file's format. By identifying organizational sections, such as the title page, chapters, and smaller structural headings, Adobe has made the navigation of large documents easier and more accurate. Here are some of the specific features:
- Both content and logical structure are included in the Adobe PDF file.
- Document content can be exported as Rich Text Format (RTF) files, allowing the information to be used in other programs or to be read by assistive technologies that aren't MSAA compatible.
- Alternate text (ALT text) can be used for images.
- High-contrast color schemes. Low vision users can override the colors defined by the document with a color scheme optimized for their useful vision.
- Keyboard shortcuts allow the user to navigate the interface without a mouse.
- Reflowable text blocks. Magnified text blocks will now automatically wrap to fit on the screen instead of requiring awkward horizontal scrolling.
- Make Accessible plug-in. This plug-in for Adobe Acrobat 5.0 provides accessibility to Windows screen-reading programs. The Acrobat Access plug-in converts untagged Adobe PDF files, including older files made with previous versions of Adobe Acrobat, into tagged Adobe PDF files that can be better understood by assistive technology.
- Adobe also has added a number of editing tools for people who are creating Adobe PDF files, including an Accessibility Checker that identifies and alerts the author to common problems. You can find out more about these at the website.
Adobe also offers a free, Web-based service at: http://access.adobe.com/. This service converts any Adobe PDF document on the Internet into HTML or plain text. The document is also reformatted into a single column of text that can be read easily by screen readers The access.adobe.com site provides two conversion options:
- The first is a Web-based form that can be used to convert PDF documents that are on the Internet. Users may type the URL to an Adobe PDF document and click a button that reads, "Get This PDF Document as HTML". The document is converted instantly into HTML and is returned immediately to the Web browser.
- The second option is to use email to send Adobe either the URL of an Adobe PDF file on the Web or to send (as an attachment) the file from a local source (floppy disk, network drive, CD-ROM, etc.). The document is converted into HTML or into ASCII text and is sent back in a new e-mail in a matter of minutes.
When access.adobe.com converts Adobe PDF to HTML, all existing hypertext links are converted to HTML links. This includes intradocument links as well as links to other documents on the Internet. Adobe also adds extra links to make navigation within the document easier:
- "Document Body" links to the start of the document.
- "Page Navigation Panel" has a numbered link to each page in the document (i.e. 1, 2, 3, etc).
- "Next" and "Previous" links are inserted between pages.
- Finally, if the Adobe PDF contained "Acrobat Bookmarks," a type of table of contents, the converted file will have a "Document Outline" with links that equate to the original Acrobat Bookmarks.