Many people opt to use PDF because it saves the formatting of their document. Please
keep in mind: Format follows function. Many people have said that avoiding PDFs entirely is often the best approach to ensuring
PDFs made by scanning a document with an office copier are not accessible unless you
take a few extra steps beyond scanning. A scanned PDF is a picture of text. As such,
a screen reader is not going to be able to read the text and the text in the image
is much too long to enter as alt text.
OCR - Optical Character Recognition
In order to make a scanned PDF accessible, the first step is to use OCR to convert
the image into text.
To see if a PDF has already been converted and is readable by a screen reader, try
to use your mouse to highlight the text. If you can highlight pieces of text, OCR
has been used. If you cannot highlight lines of text, then you are looking at an image.
To test the accuracy of the OCR conversion, copy and paste the highlighted text into a document and check
to see if the text/characters were accurately converted.
Once a PDF has been converted, the next task is to add tags. Tags allow the author
to identify headings, alt text, lists, etc. They essentially give the document structure
and allow the reader to easily navigate the document.
To determine whether a PDF is tagged, open it in Adobe Acrobat or Adobe Reader and
go to Document Properties. In the lower left corner of the Document Properties dialog,
Tagged is either Yes or No.
To add tags to a PDF you need to use Adobe Acrobat.
The easiest and best way to create an accessible PDF is to use MS Word. If you format
your document following the accessibility standards and practices discussed previously in
Creating Accessible Word Documents, your PDF will be off to a good start.