Before you create your InDesign document, you ought to consider the output format.
PDF files preserve the visual layout of an original design, making the PDF format especially suited to documents that will be printed on paper. If the document doesn’t need to be printed on paper, or if the fixed visual layout is not absolutely critical, you may want to consider creating the document in HTML instead or consider publishing it in EPUB format as an e-book. While most designers consider fixing the visual layout of a document to be preferable, this fixed design style is very inaccessible to users on mobile devices or those who must zoom in and then scroll both left and right as well as up and down. Unfixed content that can reflow to fit the size of the screen, even when zoomed in, is more usable for everyone when accessing digital content.
People are generally more accustomed to PDF files on the web than they are to EPUB files, which is an argument in favor of the PDF format over EPUB. Another argument for PDF is that more people have PDF readers installed than EPUB readers which are available by default with the Macintosh OS, but must be downloaded and installed on the Microsoft OS.
While creating an EPUB or HTML document rather than a PDF may seem like extra work, we must understand that PDF files as they exist now already require extra work in order to be accessible and to comply with federal law. The remediation process for inaccessible PDF files is a tedious process that can only be completed using Adobe Acrobat Pro or DC or other expensive third-party software where a remediation specialist tags each element of the document in order to provide the correct reading order and semantic classification. Some elements of a PDF, such as color contrast, are not able to be remediated post-creation therefore some PDF files cannot be made accessible without going back to a source file created in Word, InDesign, PowerPoint, etc.
There is at least one other significant accessibility concern worth considering with PDF files – even those that have been remediated to be fully accessible. While it is true that Windows-based screen readers like JAWS, NVDA, and Windows Eyes can read PDF documents in Adobe Reader or in Acrobat Pro, the Mac-based screen reader VoiceOver cannot read PDF documents effectively because Adobe Reader on Mac is not currently accessible to screen readers. Until that changes, PDF is not ideal for blind Mac users.
The EPUB format is an alternative to the PDF format, in particular for creating electronic books, or e-books which can include books, magazines, articles, etc. The EPUB format is less well-known than the PDF format, and fewer people have experience using it, which is an argument against it, but EPUB is growing in popularity especially among accessibility advocates as they begin to learn more about its accessibility benefits.
The accessibility benefits of EPUB include the following:
- The layout can be reflowable, meaning that it will be a single column of text that is easy to enlarge with a screen magnifier, which is important to people with low vision.
- Users can easily customize the appearance of the document to suit their needs. They can choose high contrast colors, for example, or change the font to one that is easier for them to read.
- The ability to synchronize the text on the screen with pre-recorded audio of a person (or a digital voice) reading the text aloud.
- The ability to highlight sections of the text as they are being read.
- Support for MathML.
- Pronunciation hints.
- The ability to integrate interactivity and multimedia more easily in EPUB than in PDF.
Reflowable for Fixed Layout?
Obviously as a designer, one of the most important decisions you need to make at the beginning is whether you’re going to create a reflowable layout or a fixed layout. As we mentioned before, designers tend to like fixed layouts, because they are predictable, and because they preserve the artist’s original intent in a straightforward way. People with low vision or anyone using a tablet or mobile device, on the other hand, like reflowable layouts, because they are much easier to magnify.
If you are familiar with the concept of responsive design for web sites, EPUB reflowable layouts are the same concept, applied to e-books. Reflowable EPUB documents are responsive e-books that adapt their layout to accommodate the size and shape of the reader software, device and user preferences.
Whichever you choose will have a dramatic impact on your design decisions, so you should make this decision early in the process. If at all possible, choose the reflowable layout to maximize the accessibility possibilities.
If your output format will be HTML, and nothing else, you should probably use an HTML editor rather than InDesign. You could use InDesign, but it would be an odd choice that might end up making the job harder rather than easier, especially when it comes to integrating styles with the rest of your web site.
Recommended HTML editors include Adobe Dreamweaver or Notepad++ if a free option is preferable.
You can export InDesign to other formats, such as Flash, EPS (printer files), PNG (image), JPEG (image), and XML. Each of these options has its purpose, but none of them are ideal for accessibility.
For InDesign, It comes Down to PDF or EPUB
For nearly everything, it comes down to a choice between PDF or EPUB. Both can be strong options for some circumstances. You may even decide to publish in both formats. Keep in mind the purpose, strengths, and limitations of each format, and make your choice accordingly.