Checking PDFs for Accessibility with free Tools

Is your PDF accessible? Learn how to check it. Please note that testing only with the PDF Accessibility Checker/PAC is not sufficient.

This process is particularly useful if you receive documents from service providers or colleagues. In our basic knowledge and quality assurance training for accessible PDFs , you will learn how to systematically check PDFs for accessibility.

These instructions are intended for persons who have no experience with professional tools. Professional tools such as Nuance Power PDF offer their own checking options, but these are not mentioned here. Nuance has the advantage that the founded problems can also be repaired. From version 2010, Microsoft Office has also integrated a tool for checking office documents. The errors displayed there can also be repaired with MS Office.

The tools mentioned are all free of charge and can be used by laypersons. Checking with a screen reader is useful, but should be carried out by someone who is experienced in using it. Detailed tests are described in the Matahorn Protocol, but they are hardly applicable from laypersons.

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Check in Adobe Reader DC

In the first step you need Adobe Reader DC. The program is available online for free.

Step 1: Check if tags have been deposited.

In the "File" menu, go to "Properties". In the "Description" tab, check whether "PDF with tags" says "Yes".

If it says "No", the PDF is not accessible and you can cancel the check at this point. The PDF is then not accessible according to all applicable standards.

Step 2: Meta Data

In the same tab above, check whether the meta data is available and correct. The name of the author or the organization can appear under "author". The title of the document can be entered under "Title". Further data are not absolutely necessary.

Step 3: Security

Check in the same window in the "Security" tab whether security mechanisms are activated.

The document should not be protected against printing, extracting text or generally with a password. This can prevent cooperation with assistive technologies. If assistive technologies are denied access to the document, the document is in no way accessible.

Note: Access for assistive technologies can be explicitly allowed with Adobe Acrobat. However, not all disabled persons use dedicated assistive technology. It is always preferable to dispense with security mechanisms.

Step 4: Correct Language

Check in the same window in the "Advanced" tab whether the language of the document has been stored correctly.

The correct main language of the document cannot be stored with Microsoft Office.

Step 5: Check the reflow mode

Please note: Reflow mode is generally error-prone as Adobe implemented it poorly. Reflow mode isn't part of the PDF accessibility standard, so it doesn't have to be completely error-free. For example, it does not work in Word documents saved as PDF on pages that contain an image. Nevertheless, it can be helpful to identify incorrect text formatting.

In reflow mode, all elements should be displayed in one column. Multi-column texts should be displayed in one column in the correct order. Images and tables should be displayed in the correct place. Decorative elements such as color gradients should be hidden.

Pay particular attention to the text formatting here: Are the hyphens of the hyphenation displayed in the text? Do spaces appear in the middle of words or sometimes missing spaces between words? Then it is an error. Blind persons's screen readers will misread the documents.

In the "View" menu under "Zoom" call up the item "Reflow". Or Press CTRL + 4. Reflow mode can be deactivated in the same way.

All items should appear in a logical order. Pay attention to the assignment of images and captions. Elements should not overlap and be spaced appropriately.

Bookmark available

Bookmarks are displayed in Adobe Reader on the left as an interactive table of contents that is always visible. Sub-items can be opened and closed. A table of contents is useful for longer documents such as brochures, but it is by no means detrimental.

If you don't see any bookmarks, check whether the "Bookmarks" item is activated under View -"Show/Hide" Navigation window. If the point is active and no navigation points are displayed on the left side, there are no bookmarks.

Note: Bookmarks are not part of the accessible PDF standard. However, since they are easy to add and useful for the blind and partially sighted, we recommend using them.

Optional: check with the screen magnifier

Also check the document in a contrast mode. To do this, call up the screen magnifier integrated in Windows 7 and higher. To do this, enter "Magnifier" in the Windows Start menu.

Click Options and select Enable Color Inversion.

The colors are reversed. The contrast mode can be left in the same way.

Scroll through the document and make sure that all text is legible. For tables and infographics, check that all elements are recognizable.

PDF Accessibility Checker

The free PDF Accessibility Checker (PAC) does not check whether a document is accessible. It checks whether the PDF technically meets the PDF UA standard. Even a small error in the document can cause dozens of error messages. A document can work without problems with auxiliary technology despite errors. Conversely, a document that is error-free according to the PAC can cause problems with auxiliary technology.

Neither MS Office nor LibreOffice allows you to create a PDF that PAC shows as error-free.

Step 1: The quick check

Select the file to be checked. The error report appears.

You can use the Export PDF Report feature to export an error report and share it with a service provider.

You can also look at the individual errors in the detail report. But you have to go deeper into the topic to decipher the error messages.

Step 2: The screen reader preview

The screen reader preview allows you to visually inspect the tag structure. You can see the tags on the left and the content on the right.

Search for "fig" for figure and verify that the alt descriptions in the Alt section make sense.

H1 stands for Heading 1 and is used for the main headings.

H2 stands for heading 2 and is used for the sub-headings. P is used for paragraphs. Here, too, you can check whether the tags are assigned correctly.

Also check whether the order is logical: for example, are captions displayed before the image or are multi-column texts displayed in a meaningful order?

Checking accessible PDF forms

An elementary requirement for a accessible PDF form is that it can be filled out without further measures. If a mode such as the Adobe Reader fill-in tool has to be activated for this, the form is not accessible. Adobe's fill-in mode is designed for mouse users and is unsuitable for blind persons or keyboard users.

Check whether the form can be filled out using the keyboard. Usually, the cursor or the focus should be on the first element that can be activated. If it's not, try tabbing there.

Check if:

  • the tab order makes sense or whether the tab jumps through the form without making any sense
  • Checkboxes can be activated or deactivated with the space bar
  • Radio buttons can be selected using the up and down arrow keys
  • drop-down lists can be opened with ALT + down arrow
  • Text fields can be filled in with the keyboard
  • If programmed content such as dialog boxes are integrated, these should also be checked to see whether they can be interacted with the keyboard.

testing by users

If you have blind or partially sighted colleagues with assistive technology, you can also ask these colleagues to look at the document with the assistive technology. They obviously need to know what to look out for and should be briefed.

You can also explicitly invite external users to provide feedback. This only makes sense if you take this feedback seriously and use it to improve. Such a feedback mechanism is provided for by the EU guideline 2102 for accessible websites, this does not seem to be the case for PDF at the moment.

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