If a document has been converted into a PDF format from a word document, then it should retain the accessibility features established in word. There may however be cases where you are working directly with a PDF document, and so this part of the guide is designed to show you how to check for accessibility issues and how to rectify some of the more common problems which can occur.
More detailed guidance around PDF document accessibility is available from Adobe online.
There is a built in ‘Accessibility’ checker within Adobe Professional. To locate it select ‘tools’ and it’s in the same section as the redactions tool.
Once you have done this select ‘Full check’ from the right hand list of options (shown below), leaving all the box options ticked.
This will run an automated accessibility check which will then in turn flag up any issues in need of attention.
It will then provide a report which looks something like this:
There will typically always be some issues flagged in the ‘Document’ section with red crosses against ‘Title’ and ‘Primary language’ and blue question marks against ‘logical reading order’ and ‘color contrast’. These are the most common issues which are detected on even the most straight forward documents.
In other cases there may be a range of different issues which the accessibility checker raises, such as the document not being tagged, issues with table formatting or alt-text missing from the document.
In the other tabs we will cover some of the main issues which can be raised by the accessibility report and how to address them.
 Adobe Acrobat Professional is available from Apps Anywhere
Right click against the accessibility report where this issue is flagged up and select ‘fix’. You will then get the following box display:
To edit a field, untick the ‘leave as is’ box and type in the relevant field.
The title for the document can also be accessed and modified by going into the document ‘Properties’ which can be accessed from the ‘File’ menu.
Right click against the accessibility report where this issue is flagged up and select ‘fix’. You will then be given a dropdown list of options where the relevant language can be selected.
After correcting this information select the option to ‘replace attached report’ which will then update the accessibility report shown on the left hand side of the screen putting a green tick beside primary language.
This is a category which the accessibility checker will typically refer on as requiring a ‘manual check’.
The minimum contrast ratio required to meet this check is: 4.5:1. The website Web Accessibility In Mind (WebAIM) has published a colour checker online guide to indicate what this looks like in practice.
In general a dark colour (black, navy blue, dark grey) on a light background (white or light grey) will make it more accessible. Setting the background colour to an off white or light grey colour, as opposed to pure white, can be beneficial to readers with dyslexia.
There are colour contrast tools available to download or use as a web browser plug in if you wished to check how your material scores on the colour contrast scale, for instance this one provided by WebAIM.
Among the most fundamental things from an accessibility perspective, is that your document be ‘tagged’, as this makes the document navigable.
If all goes well then the accessibility checker will identify that the document has already been successfully tagged. However, you may get a red cross against this field in the ‘document’ and ‘page content’ parts of the record.
Manually tagging a document can be a time consuming job and involves a degree of technical expertise. However, in most cases it will be possible to have the document tagged as part of an automated process.
If the document shows as not having been tagged following the accessibility check being run, please attempt the following steps:
1) The simplest way to try and resolve the issue is to right click on the ‘Tagged PDF’ icon and then select ‘fix’.
2) Please note that this can sometimes resolve the issue, but not always. If after applying the ‘fix’ you still have a red cross displaying against ‘tagged content’ in the Page Content part of the accessibility checker results, then this suggests the document is still not correctly tagged.
An example of a document where the ‘fix’ has been applied but where the document is still not correctly tagged is shown below:
While the ‘tagged pdf’ check under ‘document’ now shows as having passed, the red cross against ‘tagged content’ under ‘page content’ suggests there is still a problem. This can be a particular issue with PDF documents which consist of two or more documents which have been merged together.
To see what part of a document has been / has not been tagged, select the ‘tags’ icon from the vertical row of options on the far left of screen.
A long list of ‘tags’ are then likely to display if the whole document has been run through the process. By clicking on an individual tag you will be taken to the point in the document that the tag relates to.
3) If the issue has not been resolved it is advisable to try and return the PDF document to its original document form to check settings and make any alterations, on the basis that many PDF documents have been created from another source document, such as Microsoft Word.
To export a PDF into another file format, Select File > Export To, then choose your desired format.
4) If the original source of the document is unknown, and the automated accessibility functions within Adobe Professional have been unable to tag the document then you can request for the PDF to have tags added, provided the document is text based.
To do this to a PDF document which contains text but which is untagged, choose the Options menu in the Tags pane, then Add Tags to Document.
It is then worth checking the accuracy of the tags which have been generated as there is the prospect for errors and inconsistencies. If you need to make manual changes, the guidance provided by WebAIM can help provide instruction on how to do this.
The ‘reading order’ concerns in what order different blocks of text would be read aloud by a screen reader programme. Documents with a conventional layout will likely be read out in a linear fashion. The accessibility checker will always refer this on as requiring a ‘manual check’ – it’s only likely to pose an issue if the document has a non-standard layout, for instance text displaying in separate columns, if images are embedded within the main body of the text, or there are separate boxed off pieces of text in the margins.
Adobe PDF has a built in screen reader so it is possible to see how this works in practice. To access it select ‘view’ at the top of the menu bar, ‘read out loud’ is the second to last option.
To view the reading order the system has worked out select ‘reading order’ from the right hand list of options when in accessibility mode within the PDF document:
Each section of text identified on a page will have a number assigned to it. That indicates the reading order.
In the case of #1 which is a publisher logo ‘background/artifact’ can be selected. This will then serve as an instruction that it is not content to be read aloud. The same description can be given to anything which is not useful content to be read aloud, e.g. the message along the side of the document as to when and where the document was downloaded.
To change the read order click on the read order number displayed in the document (the cursor will become a small hand as you do so) that will allow you to edit how the content is described.
In the case of the BMJ Open article being looked at, the system has become confused by the box appearing to the right hand side of the first page which bisects the main body of text and has labelled it to be read midway through a sentence in the main body of the article:
It makes more sense for the text in this box to be treated as one block of text rather than multiple bits of separate text. To change this to one box of text click this icon:
You can then draw a box around the area you want to be consolidated as one block of text, so the page now looks like this:
It would make more sense for the summary text in the box to be read after the abstract but before the main body of the text. To change the reading order select ‘show order panel’
The order panel will display on the left hand side of the screen. By dragging things around you can re-order the sequence for text being read out.
Final reading order layout:
Article used for demonstration:
Grunfeld, Elizabeth A., et al. "Feasibility randomised controlled trial of a guided workbook intervention to support work-related goals among cancer survivors in the UK." BMJ open 9.1 (2019): e022746.
Licensed under a Creative Commons Attribution (CC BY) license.
Alternate text (commonly referred to as alt-text) is where an image or diagram is given a textual description which can be read aloud by means of explanation to a person with visual impairment using a screen reader.
To input alt-text where the PDF accessibility check flags up an issue, right click against ‘Figures alternative text – Failed’ and select ‘fix’.
You can then cycle through the different images which the accessibility checker has identified by selecting the blue arrows. If an image is ‘decorative’, such as a publisher logo, then by selecting the ‘decorative figure’ box you are telling the document to disregard this image as not relevant and it will be ignored by screen reader software.
In some cases, for instance with a photographic image, you will just need to reflect in textual form what the image conveys, e.g. ‘a Friesian cow standing in a field’.
ALT text descriptions typically should be brief and not exceed 125 characters where a description of an image is concerned.
A useful training resource for anyone wanting to know more about how to write appropriate ALT text descriptions is the Poet training tool. The guidance provided by the Poet training tool includes specific guidance around mathematical graphs and more technical diagrams.
The reading order tool covered in another tab of this libguide is also useful when checking the accessibility of tables.
First select ‘Reading Order’ from the right hand tool bar after selecting ‘Accessibility options’.
Once you have done this the table will likely appear in a read order box which will have a number in its top right hand corner indicating its ‘read order’ on the page.
Click into this box and then select ‘table editor’ from the Reading Order touch up box.
When you open table editor each cell should then be displayed within a red grid, provided the document has been initially tagged.
Fortunately, in this case all of the cells have been tagged:
The next thing to check is whether ‘data’ cells and ‘header’ cells are correctly recognised. In the above example all of the cells are being treated as though they are ‘data cells’.
To get the cells at the top of each column recognised as a ‘header cell’ it is possible to drag a box over the cells you wish to change while the reading order menu is open. Once you have done this right click within those cells, you will then see these options:
If you wish to change the value of these cells from ‘data’ to ‘header’ cells, select ‘table cell properties and you will open the window below.
You can simply change the value of the cells from here by selecting ‘Header cell’. After doing this the ‘header cells’ will be differentiated from the ‘data cells’ by their background colour.
Another way to check for cell properties is to right click within the table and select ‘Table editor options’.
You will then have the option of having ‘cell type’ to be labelled.
By selecting this option the table will then display like this, with ‘TH’ showing for ‘Table Header’ cells and ‘TD’ for ‘Table Data’:
You can also change the colour highlighting scheme within your table within the ‘table editor options’.
When using tables the advice is to try and keep the table layout as simple as is possible to convey the information. More complex tables require more knowledge and time to make them accessible.
Digital Accessibility advisors Level Access have put together guidance specifically concerning the tagging of complex tables.
If headers have already been correctly set up prior to the document being exported to PDF this will help deal with the potential of this issue arising.
However, if a PDF fails the ‘Headings – appropriate nesting’ element of the accessibility check this can be corrected within the PDF document.
Firstly expand the Headings information in the left hand accessibility report, which will then show the ‘elements’ in the document which need checking:
Highlight the element you want to investigate, and then select ‘show in tags panel’:
The first heading in a PDF document must always be a Level 1 heading.
In the case above the document has taken issue with a heading on the title page which is a ‘Level 3 Heading’, the previous heading to this in the document is a ‘Level 1 Heading’. An accessible document does not permit for Heading levels to be skipped, therefore this ‘Level 3 Heading’ will have to be changed to ‘Level 2’.
To do this right click on the Heading which needs changing, and select Properties at the bottom of the ‘menu’ options:
You will then be able to alter the heading level, in this case we are changing it from Level 3 to Level 2:
Once you have made changes run the accessibility check again, and if the headings are now accessible your document will pass this check.
Bookmarks are considered necessary for documents over 20 pages long.
If after running the accessibility check the ‘Bookmarks’ test comes back as having 'failed', you can address this by doing the following.
First right click on the Bookmarks result in the left hand margin of the PDF and select ‘Fix’:
A list of structure elements will appear from which Bookmarks can be formed. For a basic document it is suggested to use Headings, there are two Headings options ‘H1’ and ‘H2’. You can select both by holding the Control button.
Select ‘OK’ when you have made your selection. You will then be able to view bookmarks in the bookmark tab along the left hand pane:
The top bookmark will be a generic one which has been auto-generated.
First highlight all of the bookmarks below the top one and move them up ‘one level’. Then delete the top automatically generated bookmark by right clicking on it and then selecting ‘delete’:
All of the bookmarks are now identically nested, with relations between them not shown. To rectify this select a sub-bookmark which should be nested below a primary one (in this case bookmark 1.1 which sits beneath bookmark 1) and drag your mouse until the arrow indicates that it will be nested below the bookmark above:
The bookmark will then appear like this:
A video tutorial on this topic is available on YouTube.
Screen readers can experience difficulty in decoding mathematical and scientific symbols and equations. LaTeX, the commonly used markup language, unfortunately does not work directly with screen reader technology. In these cases it is advised to convert LaTeX to MathML or to an image which can be given an ALT tag.
For more information on how to make this type of content accessible, Penn State University’s guidance on this subject provides a useful introduction.