5 Common PDF Accessibility Errors

PDF is one of the most widely used format to present information on the web. PDFs are used to publish brochures, product user manuals, student text books, bank statements, annual reports, application forms, company policies, utility bills etc.

Being such a widely used file format for publishing information, one might think PDFs are capable of making the information available to a large number of users. However, people with disabilities are often excluded from getting access to the information as the PDF documents are not necessarily authored keeping accessibility in mind.

One of the biggest challenge faced by people with disabilities while accessing PDF is document being scanned and published online as an image PDF. Image PDFs are:

  • Difficult to read using a screen reader, braille displayer, text-to-speech tools etc. thereby making it difficult for users with visual impairments, deaf-blind users and users with learning impairments to access the information.
  • Don’t reflow, thereby making it difficult for low vision users to access the information.
  • Difficult to interact with using a keyboard, thereby making it difficult for users with dexterity impairments to access the information.

Well, image PDFs create a serious hurdle for accessing information as far as people with disabilities are concerned. However, for the purpose of this blog we will be focusing on text based PDFs and what are the 5 common accessibility issues faced by people with disabilities and outline implementation techniques to fix them!

Note: Implementation techniques included below are applicable to Adobe Acrobat Professional DC.

1. Headings

Headings are there but they are not necessarily tagged as such! 

Most PDFs floating on the web make use of different presentation techniques for adding headings and sub-headings in a document but they are not tagged as headings.

So why should we tag headings?

Tag the headings as users of screen readers rely on them to understand the document structure. Not only that all screen readers provide their users to jump from one heading to another. So tag the section and sub-section headings and do so wisely!

<H1> should be followed by <H2>, <H2> should be followed by <H3> and so on…

To add heading tags:

  1. Go to Advanced > Accessibility >Touch-Up Reading Order
  2. Draw a rectangle around the content that needs to be marked as a heading
  3. Click the desired heading level buttons from the Touch-Up Reading order

Perform the above steps for all the section and sub-section headings of the PDF document!

Screenshot showing Reading Order dialog with Various buttons such as Heading 1, Heading 2 etc

2.      List:

Numbered lists or bulleted lists, they are often there but are not list for screen reader users!

PDF documents comprise of related content that is presented using fancy bullets and sequential content that is presented using numbered lists. However, these are lists visually but not semantically!

Yes just like headings, lists are not tagged so users of screen readers will not perceive the information as a list.

Why should lists be tagged?

Tagging related content using list will render the information as a list for screen reader users. Users will know where the list begins or ends, how many items in a list etc.

So how to tag a list? Here we go!

  1. Select the text, right click on it and then select “New Tag”
  2. Select Type: List” from the available dialog.
  3. Repeat Step 1 and then Select Type: List Item” from the available dialog.
  4. Repeat Step 1 and then Select Type: Label” from the available dialog.
  5. Repeat Step 1 and then Select Type: List Item Body” from the available.
  6. Select the list item text.
  7. Right-click on the tag and then select “Create Tag from Selection” This will help to add the text to the content.

Screenshot showing New Tag properties dialog for a List item body.

3.    Images:

Yes, they are there and they are appealing! But what information do they convey?

PDF documents include icon images, logos, product images, graphs, charts etc. But what information do they convey is not known to users with visual impairments. They lack descriptions.

Textual descriptions that convey the purpose of the image needs to be specified for all the informative images of a PDF document. This description will then be rendered by screen readers for their users!

An image is worth a thousand words!

But without descriptions they have no value as far as users with visual impairments are concerned…

So how do we specify textual descriptions for images in a PDF document?

The answer is alternate text!

To add alternative text to an image in a PDF document

  1. Select the image, right click on it and then select “New Tag” option.
  2. Select “Type: Figure” from the available dialog.
  3. Right click on the image and then select
  4. Go to the Tag tab, in the Alternative Text field enter the alternative text for the image.

Screenshot showing Object Properties dialog .

Tip: Decorative or background images need not be provided alternative texts, tag them as an artifact!

4.      Tables:

Tables, data or layout, simple and complex are all there and are tagged as well. So what is the problem? Data tables lack row and column headers!

Table headers are present visually and are presented using bold font styles but are not tagged as headers.

So why do we need to tag table headers?

Table headers help screen reader users in understanding tabular information easily. A screen reader reads one cell at a time, in left-to-right and top-to-bottom order. In the absence of headers, a screen reader will render all the cells as data cells and users will not know which data cell is associated with which row and column header.

So how to tag table headers?

  1. Select the text, right click on it and then select “New Tag”
  2. Select Type: Table” from the available dialog.
  3. Repeat Step 1 and then Select Type: Table Row” from the available dialog and continue as per the number of rows available in the table.
  4. Repeat Step 1 and then Select Type: Table Data Cell” from the available dialog and continue as per the number of cells available in the table.
  5. Select the text and the data cell tag created.
  6. Right-click on the tag and then select “Create Tag from Selection” This will help to add the text to the data cell.
  7. Select “Accessibility” tab from the right panel and select “Reading Order”
  8. Right-click on the table and select “Table Editor”
  9. Drag the data to select the text that needs to be defined as a header cell.

Screenshot showing Table cell properties dialog with Type: Header Cell and Scope: Column selected .

Tip: For complex data tables, user “header” and “id” properties to associate data cells with their respective header cells!

5.      Links:

Links are present but can be clicked only with a mouse!

PDF documents comprise of links to external sites, email links, footnotes and endnotes, and table of content links. Either all or some of them do not work with a keyboard.

When we hover over the links, the pointer changes to hand cursor but can we navigate to the link with the Tab key? The answer is often No!

Links need to be tagged to make sure that they can be accessed with a keyboard. Links if not tagged will be rendered as plain text by screen readers. If we can click a link with a mouse it should work with a keyboard as well.

So how do we tag links?

To tag links:

  1. Select the text that needs to be tagged as link
  2. Right click and select Create link option
  3. In create link dialogue, select the “Open a Webpage” radio button. Click Next.
  4. In Edit URL paste the URL.

Screenshot showing Create Link dialog with Open a web page radio button selected .

When documents are converted into PDF format, it is essential to know whether they are accessible or not. Though several online PDF accessibility checkers are available, it is advised to have a professional organization to help ensure that your documents comply with the required accessibility standards and guidelines such as WCAG 2.0 and Section 508.

Some references:

Need help with making your PDFs accessible? Write to sales@247accessibledocuments.com today.

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