How to make a PDF accessible
Make a PDF accessible offline with PDF by Zaweba: tag the document, add alternate text, language and title, then run a 32-rule check and fix what it finds.
You can make a PDF accessible with PDF by Zaweba by opening Tools > Accessibility, tagging the document, setting alternate text for its pictures, its language and its title, and then running the built-in check of 32 rules. The check tells you what still needs work and can fix many problems for you. It all runs offline on your own PC.
An accessible PDF is one that a screen reader can read in the right order, with headings it can jump between, pictures that are described, and a language so the voice pronounces the words properly. Without those, a blind or partially sighted reader may hear a jumble or nothing at all.
Starting with the right file
The PDF itself, and ideally one with real text rather than a scan. If the document is a picture of a page, it needs OCR first so there are words to tag. Then allow some time: the automatic steps do most of the work, but a person still needs to write good descriptions of the pictures.
Tag, describe, check
Start with tagging. Tag the document automatically wraps untagged content in tags: paragraphs, headings judged by their size, figures, links, form fields and comments. Running headers, footers and page numbers are marked as artifacts so a screen reader doesn't read them out on every page. Lists and tables are not recognised automatically, so make those yourself in the Tags window.
Next, alternate text. Go figure by figure and write a short description of what each picture shows and why it is there. A picture that is only decoration can be marked Decorative, which tells a screen reader to skip it.
Set the document language and the document title. Once the title is set, the window shows it, which is what a screen reader announces when the file opens instead of a file name like scan_0042.
Then run the check. Tools > Accessibility works through 32 rules covering permission, tagging, language, title, reading order, alternate text, tables, lists, headings and more. For each problem you can choose Fix, Skip rule or Explain, and Check again shows what is left after your changes.
The quick route
If you would rather not do each step by hand, Make accessible runs the built-in action, then takes you to alternate text and the check. A setup assistant also guides you through the steps in order, which is a good way to learn the process on your first few documents.
Checking the automatic work
Read the explanations. The Explain button says why a rule matters, which helps you decide whether a fix is right or whether a rule really doesn't apply to your document. Skipping a rule is fine when you know why.
Don't trust heading detection blindly. Tagging judges headings by size, so a large pull quote may be tagged as a heading, and a small but real heading may be missed. Scan the result in the Tags window and correct it.
Write alternate text for a listener, not for a search engine. Say what matters in the picture in a sentence or two. For a chart, give the point the chart makes rather than describing every bar.
When you are done, Save report as an HTML page. It gives you a record of what was checked, useful when an organisation asks you to show that a document meets its accessibility policy.
Bookmarks can also be made from headings in the same set of tools, which helps every reader find their way round a long file, not only those using screen readers. PDF by Zaweba keeps the whole job on your PC, from tagging to the final report.
