A study on how Mobile Screen Reader’s render Accessible PDF’S

In the past, Screen Reader users found it difficult to access PDF’s on mobile devices even though PDF’s were made accessible. Now the scenario has changed !

I thought to study how screen reader identifies and interpret different elements in an accessible PDF file on mobile platforms. So I chose the leading screen readers VoiceOver on iOS 12.0 and TalkBack on Android 8.1 for the study using Acrobat Reader DC (App version 18.4.1.208250).

The study was carried out for different elements:

  • Image
  • Heading
  • List
  • Link
  • Table
  • Form elements: Text input field, radio button, check box, etc.

So here is the result of the study!

Following table lists how Talkback and VoiceOver interprets various elements in a tagged PDF file:

Element VoiceOver Talkback
Image Renders it as “image” and announces the alternate text. Renders the alternate text but does not identify it as image. However the rendering of alternate text is inconsistent sometimes the alternate text is rendered and sometimes the image is skipped.
Heading Renders it as a “heading” and announces the heading level and text appropriately. Renders it as a “heading” and announces the heading level and text appropriately.
List Announces “List start” and “List end” at the beginning and the end of a list. It also announces the prefix for the list items. Announces the number of list items information such as “in list 4 items” at the beginning of the list. It also announces the prefix for the list items.
Link Renders it as “link” and announces the link text. Renders it as “link” and announces the link text.
Table Renders the table content. However, it does not identify the table as a table. Renders the table content. However, it does not identify the table as a table.

In the case of form elements, both Screen readers identify the visual label but do not render the form elements.

All in all both Screen Readers interpret the elements identically. VoiceOver is having the slight edge as it renders the image along with the alternate text.   

Hope to see improvements with regards to table and form elements in an accessible PDF document that will help mobile screen reader users to access the content on the go. Don’t forget to share your experience in the comment box below.

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