3.3 HTML & CSS
Making Ebooks with InDesign: Module 3, Step 3
Making Ebooks with InDesign: Module 3, Step 2
InDesign to EPUB
Before reading this, you might want to read:
This article is a primer on the choices a user is given, when exporting from InDesign, that will impact the accessibility of an ebook.
You can manipulate InDesign into creating better ebooks a number of ways, ranging from setup tricks to using styles creatively. But many tricks are also buried in the extensive EPUB export options. In this article, we’ll walk you through the choices.
One of the most useful things you can do for the accessibility of your ebook content is also the simplest: Opt for export to EPUB 3 instead of EPUB 2. EPUB is a specification defined by the International Digital Publishing Forum (IDPF), an organization that was folded into and taken over by the W3C in 2017. Maintenance of the EPUB spec is now assumed by working groups within the W3C. The EPUB 3 spec was approved in 2011. EPUB 3 assumes the EPUB 2 spec but takes a slight left turn to a set of definitions that are explicitly accessible. A major goal of EPUB is to facilitate content accessibility through navigation, structural hierarchy, rich media, and semantic HTML.
Screenshot of the first screen of EPUB export options from InDesign. From this window, users can opt for EPUB 3, and point to a TOC style for navigation.
Under the options at File —> Export —> EPUB (Reflowable), InDesign will default to EPUB 2. The simple action of opting for EPUB 3 amplifies the accessibility of the resulting document. It is not possible to overstate this. Some ebook retailers report that up to 60% of brand-new content is still EPUB 2. The work of having to accommodate that older specification is significant for ebook vendors.
There is nothing wrong with EPUBs made to the EPUB 2 spec, per se, but we would compare it to opting for something flat over something three-dimensional. Please consider selecting EPUB 3 the next time you make ebooks.
In the Text window, there are a couple of notable things. Please be mindful to map lists to the correct HTML for lists. Converting a bulleted or numbered list to text will strip that content of meaning in some contexts. Imagine listening to a list being read as a long run-on sentence without pause and without any indication that it’s a list. It wouldn’t be a good reading experience.
The second window of the EPUB export options for reflowable ebooks. Be mindful of keeping lists mapped to ordered and unordered lists, instead of converting them to paragraphs.
Under the Object tab, you can manipulate InDesign into turning out a responsive ebook — almost despite itself. Asking the export to determine the size of images as relative to text flow, rather than fixed, means that the size of images will depend on the size of the end user’s screen. The CSS definitions will be output in percentages, rather than pixels.
Be mindful not to check Ignore Object Export Settings, particularly if you’ve applied semantics, alt text, or grouped items to export as an image.
The third window of the EPUB export options for reflowable ebooks. Consider opting for CSS Size: Relative to Text Flow for more responsive ebook design.
Under Conversion Settings, we encourage you to export images to JPEG rather than GIF or PNG wherever possible. Using JPEGs results in a more compact EPUB. The size of the EPUB contributes to the usability of the content; i.e., larger is harder and clunkier to use, especially on older devices.
The fourth window of the EPUB export options for reflowable ebooks. Where possible, choose the JPEG format for smaller, easier-to-use ebooks.