EPUB: Supporting Learner Variability in EPUB Creation
Accessibility at a Glance
Accessibility at a Glance
Below are resources to understand and help create accessible EPUBs:
What is this resource about? This resource provides a definition and information about developing EPUBs, Selected EPUB3 Best Practices and an Example of creating accessible versions of digital images.
Why is this resource important in higher ed? Accessible EPUBs have the potential to offer robust representations that combine different forms of media. They also engage educator and learner participation and sharing in the open education movement.
Provide multiple means of engagement: EPUBs can combine different forms of media beyond text that can increase student engagement and understanding.
Provide multiple means of action and expression: EPUBs, when created with interactive elements, can provide learners with multiple opportunities to express and act on their knowledge and understanding.
Provide multiple means of representation: EPUB is a recognized standard that provides the capacity for combining different types of media together in one single package.
EPUB as a Standard
The International Digital Publishing Forum (IDPF) defines EPUB as "the distribution and interchange format standard for digital publications and documents based on Web Standards. EPUB defines a means of representing, packaging and encoding structured and semantically enhanced Web content—including XHTML, CSS, SVG, images, and other resources—for distribution in a single-file format."1
EPUBs are open source digital books that are viewable on desktops, tablets, and mobile devices. EPUB content can include text, images, audio, videos, and interactive elements. When the content is designed with learner variability in mind and uses the accessible features of digital publications, that content becomes a powerful tool in education. EPUBs not only have the potential to offer robust representations that combine different forms of media, but they also engage and affirm educator and learner participation and sharing in the open education movement.
Developing an EPUB can become a highly technical process. Matt Garrish’s book, Accessible EPUB2 is a resource for best practices in accessibility and addresses usability issues, and using them as a foundation for creating a universally designed EPUB3 format digital book that supports learner variability through the flexible use of media. EPUB creators control the accessibility of their publications. Choosing tools and post-production workflows that take accessibility into account are essential to the creation of accessible EPUBs.
E-readers are electronic mobile devices for reading digital books and publications. There isn't any one e-reader that is perfect for everyone. Depending on the device(s) that a person has, the choice of which e-reader to use is a personal one. The Book Industry Study Group keeps an updated list of e-readers that support the EPUB format. The AEM Center website also has a resource on Digital Reading Technologies that support EPUB.
SCREENREADERS AND CAPTIONS
To maintain visual and auditory accessibility on e-readers, EPUB creators must account for the use of screenreaders and captions in digital materials.
Some learners will need support for text and visuals in the form of a screenreader, which is a specialized software that voices onscreen text. Other learners will benefit from the inclusion of captions in videos. Captions provide text support for audio and come in the form of open captions, closed captions, and subtitles.
Caption It YourselfTM provides straightforward guidelines for creating captions.
Selected EPUB3 Best Practices
These best practices are critical in providing access for a variable learner population who differ in the ways that they perceive, understand, and are engaged by digital content contained in an OER or eBook. One of the advantages of the EPUB format is that there are many e-readers on the market that support it, limiting the number of devices that will encounter usability issues.
- Separate content and presentation
- Provide complete navigation
- Create meaningful structure
- Use alt text and long description for images
- Use images only for visual components and not for tables or text
- Use MathML for mathematical expressions
- Provide alternate access to media content
1. Separate Content and Presentation
It is essential that the content and presentation of a digital book are flexible rather than fixed. The visual appearance of content should not be the primary means of conveying meaning to readers. Instead, mark-up, including related style sheets, should provide appropriate user supports. Styles, for example, can and should support those who are more visual readers in identifying the structure of and key points in the content. However, it is important to note that an overuse of styles can impact the capabilities of screenreaders, for example, in applying alternate style sheets that change the contrast of the text and background.
An example is the UDL On Campus screen recording of the EPUB version of the Creative Commons: A Shared Culture video, which can be downloaded from Google’s EPUB3 repository. The recording shows the EPUB with both its original and user-customized layouts in iBooks. If the original layout has light colored fonts and background. Some learners may choose to read the content in sepia mode rather than retain the original EPUB colors. Giving learners choice in content representation is valuable for those who want to see the content rendered in multiple ways.
2. Provide Complete Navigation
By providing complete navigation, authors of EPUBs affirm the importance of access to and organization of the content. Authors develop what is called a logical reading order that shows the structure of a digital publication. For sighted readers, seeing larger, bolder, and/or italicized text may signify important parts or aspects of meaning of the text; but screenreader users will need proper mark-up that differentiates sections and notes semantic inflection. When content is marked up as part of a chapter, glossary, or index, learners should be able to independently navigate through relevant parts of the content with or without screenreaders.
3. Create Meaningful Structure
Whether an EPUB is short or long, simple or complex, meaningful structure is integral to navigating and understanding its content. The display of information impacts a learner's executive functioning. Learners can come to a text feeling disorganized, unprepared, and overwhelmed. A good EPUB will contain scaffolds (supports) that keep information organized and meaningful for learners. Some ways to provide this support include the use of graphic organizers that provide a hierarchical overview of the content, lists that outline critical parts of a text, and page numbers that support learners in instructional and social aspects of reading (i.e., uses associated with assigned readings and reading aloud in class). By having such structure, readers are given the tools that prepare them to strategize where to go within an EPUB.
4. Provide Appropriate Metadata
Including appropriate metadata is an important part of enriching an EPUB with data that provides learners with meaningful information about its content. For example, if a consumer were to go into a department store and look at clothing, an item's tags would provide additional information about it such as its fabric type, price, and size. This is meaningful data that informs the consumer's decision on whether or not to purchase an item. In the context of EPUB creation, metadata elements are used to “tag” a work with meaningful data such as its author, subject, and publication date. This optimizes the work as a whole for use with cataloging and database storage, search engines, and by learners and curriculum designers.
5. Use Alt Text and Long Descriptions for Images
Alt text and long descriptions are critical in providing access for users with visual disabilities and for those with situational disabilities where images aren't visible on an e-reader device. Alt text is a short text description of visual information. It should be brief (under 10 words) and communicate the purpose of the image based on its context. It is used for all images, including photographs, diagrams, charts, screenshots, icons, and more. A long description is a more thorough explanation of an image used for more complex images. When alt text is insufficient to describe fully a more complex image such as a diagram, a long description should be provided. It should be written in a way that is objective and considers the purpose, goal, and context in which the image is being used. When relying heavily on visual content in an EPUB, image descriptions are paramount in providing access to content.
There are many different image formats, and while Portable Network Graphics (PNG) and JPEG are the most common, there is a push towards the use of Scalable Vector Graphics (SVG) because it is based on Extensible Mark-Up Language (XML). SVGs can be scaled without pixelation with the use of special magnifying software.
The Diagram Center's EPUB on accessible images contains several examples that show how to render accessible images in an EPUB. In addition, the Diagram Center's web site has a recommended list of image guidelines for EPUB3.
6. Use Images for Visual Components and Not for Tables or Text
Tables are used primarily to summarize key points, organize large datasets, and show side-by-side comparisons. They should be clear and readable both vertically and horizontally by screenreaders. It is important that table data to be properly marked up. When data is properly marked up in an OER resource, future creators of EPUBs can update the data within the table and retain its access features when they share the newer versions.
IDPF provides examples and guidance on how to work with tables with varying datasets.
7. Use MathML for Mathematical Expressions
When it comes to providing options for the representation of mathematical expressions, MathML offers the greatest flexibility for learners, including those who use assistive technologies such as screenreaders and refreshable Braille. MathML allows for basic and complex math expressions to be seen and read and supports the language of mathematics and math processes for all users. Variables, symbols and equations are just some of the many mathematical components supported within MathML. MathML expressions should always include alt text as a fallback for when screenreaders do not support MathML natively.
The following example of MathML includes the alt text, "a plus b equals 8":
MathML Central, an online tool provided to the public by Wolfram Research, is helpful in validating MathML expressions and can be helpful in generating MathML for complex equations. IDPF additionally recommends using MathSpeak to help write MathML alt text.
8. Provide Alternate Access to Media Content
The media content in any EPUB should be accessible and flexible in its presentation. Video content offers dynamic ways of representing and engaging learners with the curriculum. For videos that are made by the EPUB creator, providing captions and a transcript are essential in supporting access to video content. For work that is not created by the EPUB creator, it is important to link to content that is captioned and/or transcribed. If videos are an integral part of an EPUB, those videos should not solely live within the EPUB as embedded files. They should also be viewable on web sites with media channels or made available for download—doing this gives learners options in accessing the content. This practice is critical in the context of OERs. Making media available in multiple ways, in addition to ensuring its accessibility, creates the maximum benefits for the EPUB in question for users, its creator, and the OER movement as a whole.
The videos within this resource give learners ways to alternately access the content because they can be found on the UDL On Campus YouTube Channel.
The Accessible Image Sample Book, provided by the DIAGRAM Content Working Group, is a free online resource that shows some of the many options for creating accessible versions of digital images. Here is a sample of the Accessible Image Sample Book on GitHub.
1International Digital Publishing Forum. EPUB. http://idpf.org/EPUB
2Garrish, M. (2012). Accessible EPUB3. Sebastopol, CA: O’Reilly Media, Inc. Retrieved from http://shop.oreilly.com/product/0636920025283.do
EPUB (currently version 3) is an open standard maintained by the International Digital Publishing Forum (IDPF) as a distribution and interchange format standard for digital publications and documents. It aggregates content components into one file and is intended as a single e-book format.
The International Digital Publishing Forum (IDPF), formerly known as OeBps, is a trade and standards organization dedicated to the development and promotion of electronic publishing.
SVG is a language for describing two-dimensional graphics and graphical applications in XML, as developed under the W3C process.
Audio, in this context, is a digital form or representation of sound. It is a format that stores, copies, and produces sound according to the data in its file(s).
Captions are words that are displayed on a screen to describe audio content.
A screenreader is a software application that converts the text content of a computer display into speech in order to transmit the information primarily to blind or low vision users.
UDL is an educational approach based on the learning sciences with three primary principles—multiple means of representation of information, multiple means of student action and expression, and multiple means of student engagement.
Video is the recording, reproducing, or broadcasting of moving visual images.
Metadata is information that refers to one or more pieces of information that can exist as separate physical forms (data about data). Any description can be considered metadata. In the information technology world the term is often used to indicate data which refers to digital resources available across a network.
Alt text (alternative text) is a brief description of a single image designed to be read by a screenreader as an alternative to that image.
A long description is a more extensive description of an image, typically a complex image, designed to be read by a screenreader as an alternative to that image.
MathML (Mathematical Mark-Up Language) is an XML-based language used to display mathematical content.
A transcript provides a written version of content that has been presented in an audio, visual, or audiovisual format.
Open educational resources (OERs) are any type of educational materials that are openly and freely available for use.