Achieve accessible, interactive and easy-to-use PDFs for all users, through various stages of preparation, remediation and final validation.
Achieve accessible, interactive and easy-to-use PDFs for all users, through various stages of preparation and final validation.
For years, one of the best known formats for documents, forms, design, printing, maps and interactive publications is PDF. It was initially created as a proprietary Adobe format and was launched more than 25 years ago, precisely in June 1993. It was developed as part of a paperless office concept. In July 2008, the PDF became an open standard and is published by the International Standards Organization as ISO 32000-1. It is from then on that it achieves greater acceptance and popularity worldwide.
Nowadays, PDF files can contain a wide variety of content beyond plain text and graphics, including interactive elements such as annotations and form fields, buttons, layers, links, three-dimensional objects, and other data formats. In addition, the PDF specification provides encryption with security settings, digital signatures, attachments, and metadata for various workflows.
But despite all the advances and features that the PDF format was adopting, not all users could take advantage of them if they did not comply with certain basic accessibility guidelines. So in 2004 he started a project called PDF/UA, with a set of specifications and accessibility requirements for accessible applications and PDF documents.
For those who are equipped with the appropriate software, PDF/UA compliance ensures access to people with disabilities who use assistive technology, such as screen readers, screen magnifiers, joysticks and other technologies to browse and read electronic content.
Taking into account these accessibility specifications allows us to ensure that any user can access the content included in a PDF document, regardless of its condition or limitations.
The following is a list of the preparation steps to achieve accessible PDF documents, using Adobe InDesign and Adobe Acrobat Pro applications.
Each PDF document must contain metadata that provides basic information about the file. This will be the first information that assistive technology will transcribe for the visually impaired:
- title of the document
From Bridge, this is done by selecting the document and then the workspace called Metadata. With InDesign using the File – File Information menu command. With Acrobat Pro from File – Properties – Description – Additional metadata.
It is important that the title of the document is displayed in the title bar, instead of the file name. Both Acrobat and InDesign allow you to configure it like this.
If the content of a PDF document is not tagged, it will never be able to validate as accessible because it requires a markup structure for use from assistive technology. An untagged document will display an empty Tags panel in Acrobat. The message “No tags available” will be displayed.
As in the HTML language, each element in a PDF must be assigned a corresponding tag: images, headings, subtitles, paragraphs, lists, tables, etc. Tags provide structure, logical reading order and semantic markup.
This can be done directly from InDesign by assigning PDF tags to paragraph styles. To do this, the styles must be created and then use the Edit All Export Tags command in the Paragraph Styles panels.
It is possible to create an accessible PDF document directly in Acrobat, but it is easier to use Acrobat to remediate an accessible document generated in InDesign.
Heading levels are elements that provide structure to the contents and document information. They ease the navigation for visually impaired people through the document: with the help of a specific key command for screen readers, it is possible to list each document heading (as well as other elements such as hyperlinks, lists, etc.).
- H1: Main heading. It is assigned to the title of the document, but also as a heading for important sections that divide a document, chapters, etc.
- H2: Heading Level 2
- H3: Heading Level 3
- H4: Heading Level 4
- H5: Heading Level 5
- H6: Heading Level 6
An H1 can include several H2, one H2, several H3, etc. It is important to preserve this hierarchy of heading levels and assign a heading tag by its function and not for a style effect. Therefore, some elements, such as lists, must be grouped under a heading level to facilitate the understanding of the structure by visually impaired people.
It is important to provide those who use screen readers such as NVDA, clear and relevant hyperlinks or appropriate URLs to help understand the purpose of the hyperlink.
The language must be specified globally in the exported document. InDesign allows you to indicate the language when exporting as a PDF, using the Language option in the Export as Interactive PDF dialog box.
Both assistive technologies and user agents can interpret the text more accurately when the language of the document is identified. In this way, screen readers can load the right voice along with pronunciation rules. As a result, users with disabilities will be able to understand the content.
In the event that the document contains multiple languages, it is key to notify language changes to facilitate the understanding of each word and paragraph, which will be transcribed by screen readers. You can indicate the language of each paragraph from the Paragraph Styles, and each particular word from the Character Styles panel.
The images must contain textual information. When it comes to images, screen readers and other assistive technologies cannot transcribe this information, therefore, it is important to provide alternative text.
To add alternative text to an image we must use the Object – Export Options command and then the Alternative Text – Custom tab. In Acrobat it is indicated from Set Alternative Text.
Decorative images that do not contain any type of information; they will not need to be transcribed by assistive technologies because they will interfere the browsing experience of people with visual disabilities, who will not understand the purpose of them.
To do this, we must assign the Artifact tag to a decorative image or graphic. From InDesign, the Object – Export Options command is used and then the PDF tagged – Artifact.
It is important to take into account some general rules for the use of color in documents. The information must not only be provided through color; it is also necessary to provide sufficient contrast between the text and the background.
The contrast range must be equal to or greater than 4:5 or even better 7:1. In order to measure this, it is recommended to use the Colour Contrast Analyser desktop application. This application helps determine the readability of the text and the contrast of visual elements, such as graphic controls and visual indicators.
When validating an accessible PDF, color contrast is a requirement to be done manually.
Table of Contents
Also known as the thematic index, a table of contents (TOC) shows the structure of the contents of the publication. In addition, it allows navigation through each PDF document.
The benefit of generating a table of contents directly in InDesign is that the links are created automatically; however, the formatting is more visually restrictive than the manual form.
To generate a table of contents in InDesign we must use the Table of Contents dialog box, which is located at the end of the Layout menu.
Any PDF document that equals or exceeds 20 pages must contain Bookmarks, otherwise it will not validate as accessible. Bookmarks help navigate within the contents of each document.
To create bookmarks in InDesign, we can do it from the Bookmarks panel or automatically using the Table of Contents dialog box.
To set a logical reading order, we must drag the items in InDesign into the Articles panel, having selected the command in the Use for reading order in tagged PDF.
Once the accessible PDF has been generated following all the stages mentioned above, it is time to validate the document through an application such as Adobe Acrobat Pro. For more advanced users, the PAC (PDF Accessibility Checker) application is recommended.
The following is a brief glossary of terms related to and mentioned in this article:
It means making sure that a website, application or document is easy for everyone to use. Good accessibility increases the market, minimizes risk and improves user satisfaction.
International Standard Organization or International Standards Organization. It promotes the use of proprietary, industrial and commercial standards worldwide. He currently works in 196 countries.
Portable Document Format. It is a storage format for digital documents independent of software or hardware platforms.
PDF/Universal Accessibility or PDF/Universal Accessibility. It is the informal name for ISO 14289, the international standard for accessible PDF technology.
Now that you know the stages required to create PDFs accessible to everyone, it is only a matter of minutes to put them into practice for each electronic publication and turn them into daily routines of our work.
You can learn more about how to create accessible PDFs in the Adobe InDesign: Accessible PDFs course.
We also offer the service of creating accessible PDF documents with logical reading order, tags, hyperlinks, bookmarks and validation reports.