Tip #17
Using PDF files
Because putting up PDF (Portable Document Format) files on your sites is common, I want to make a couple of comments about PDF files. You would link to a PDF file as you would a regular HTML file, using the Properties panel.
A PDF file basically takes an existing document and presents it graphically (as a large graphic image) as a "reproduction" of that page or document. PDF files are produced from (newer) scanners or from someone installing Adobe Writer on their local computer and selecting that "printer" from the desktop publisher or word processor which created the document.
PDF files present a barrier to two types of audiences: those who are visually disabled and those with slower connections.
- PDF files do not have to be large files, but often they are. I have seen "web publishers" put up PDF files which are a half a megabyte or more in size. Such files take a long time to download on a slower connection. Although there are various factors affecting download time, in general assume that if a user has a 28.8 Kbps modem, about 3 kilobytes will download per second. There is not much you can do, if you have to use a PDF file in order to provide a particular format to your user. Sometimes larger documents can be split into parts, but that will not always work.
However, anytime you link to a PDF file, unless it is quite small in size, you should indicate the filesize on the page with the link. That way, if a user has a slow connection, they don't have to click on the link and then wonder what's happening. - Because a PDF file is primarily a large graphic, screen readers cannot read the "text" in that file. The Adobe Company is working with screen reader manufacturers to make PDF files accessible. Adobe presents online various accessibility tools for helping people read PDF files. These options are outlined at their website at www.adobe.com/products/acrobat/access_overview.html. At some point you should take the time and review the information at the Adobe site.
- One option for getting a "translation" of PDF files, is this page put up by Adobe: access.adobe.com/simple_form.html. The program at the Adobe site produces an HTML document that is immediately returned to the user's browser. Using a screen reader or another device, the user can then get the information from this PDF file. When you type in the URL on this form, be sure to include the complete URL including the initial http://.
Remember that the results you get back may not look pretty on the screen, for someone who is LOOKING at the feedback. These were designed to provide text that a screen reader could "read" to someone who is blind.
How well either of these options work to produce an alternative text version of your PDF depends on the quality of the PDF file and the types of things found in the PDF document. If the PDF document is "fuzzy" or the copy is bad, you will have a lot of character recognition problems (for example "n" may be seen as an "r" and an "i"). Even if you do have an excellent PDF file -- there is still a huge possibility of having some problems with the character recognition. The Adobe access programs seem to deal fairly well with simple text, even if it is in columns, but if you have graphics in your document, and graphics with text, the conversions do not work well. Tables in the PDF document can also become garbaged in the translation.
These tips are created as part of a class on Dreamweaver Basics.