Designing an ebook is complicated: its somewhere between print and web design, but presents many unique challenges. In this section, 6.5 Ebook Design, I want explore the design process for the final Digital Aladore EPUB edition.
In a few earlier posts, I touched briefly on optimizing the EPUB for reader devices by creating smaller XHTML files, cleaner markup, and reasonable image sizes. However, up to this point we haven’t looked closely at styling the ebook. While the draft version of the Aladore EPUB is useable and readable (an improvement over the gibberish filled automatically generated ebook or overly compressed PDF provided at Internet Archive), a book is more than raw text. The designer must make decisions about how to most effectively present the content. The format, layout, typography, and design elements are influenced by practical and aesthetic concerns, and informed by the user model.
In the draft Aladore EPUB, there is no CSS or inline styling, thus the presentation is left up to the defaults of the reading app rendering the book. These defaults can be wildly different, having even less consistency than web browsers. For example, some readers such as Nook, automatically indent paragraphs and add a slight margin from the edge of the screen. Others do not, leaving the text uncomfortably close to the edge. This hints at the challenges of designing and styling an ebook. The file needs to be flexible enough to meet user needs and expectations in a highly diverse and non-standardized environment.
Ebooks are used on many device types, including e-ink readers, tablets, phones, and computers. This presents several hardware challenges:
- Screen sizes vary from tiny to huge. A ebook perfectly styled for the average 6” e-ink screen can look strange on a 10” HD tablet. In general, styling needs to be based on relative measures, not specific dimensions.
- Screen refresh rates vary considerably, since dedicated ereaders can save battery with minimal refresh rates. However, these low refresh rates often cause interactive features to produce strange looking artifacts or not function well.
- Input method, the devices support interacting with the document via several different means. Some older ereaders have only a few hard buttons allowing very minimal interaction with the text, other than turning pages. Newer ereaders and tablets have touch screen only which allow a more tactile and gesture based interaction. Computers are mostly mouse and keyboard focused which allows more detailed inputs, but creates a considerably different experience interacting with the text.
- Hardware specs vary considerably. E-readers tend to have low end processors and small memory to maximize battery life, thus any rendering that requires processing or loading large files becomes cumbersome.
These issues are compounded by a number of software based challenges, since ebooks must be rendered by a reading application. Users are aware that they have a choice in what web browser they use and that there is slight variety in how each browser renders content. Designers use a variety of techniques, such as browser CSS prefixes, to create markup that will render consistently in the different browser engines.
Dedicated ereaders typically have a built in reading app with a specialized and proprietary rendering engine developed by the device maker (often based on Adobe Digital Editions). Since the app is essentially hidden, users are not really aware it. There is very little information available about the different engines. Tablets can install independent reading apps, so the user can choose one based on the functionality and look they want (more often the commercial ecosystem they buy from). However, since these rendering engines are more niche, less standardized, and less well known than web browser engines, there are not as many techniques for designers to automatically account for differences. Furthermore, results from EPUBTest demonstrate that support for the full specifications of EPUB varies considerably and is low overall (if you want to try it yourself, a set of epub3 books can be downloaded to systematically test devices for functionality and feature support). Because of these challenges, there are few specific guidelines for styling and formatting ebooks.