Using Adobe InDesign to create accessible EPUB 3 files
Update: Adobe InDesign CC now supports fixed layout EPUB 3. The exported EPUB 3 can now retain the elaborate layout and looks of the InDesign document. The process is explained in the 9 min video tutorial - How to design fixed layout EPUB on Adobe website. Here is another video on creating fixed layout EPUB from Adobe TV.
Publishers must follow best practices for content markup and make use of accessibility guidelines when they export their content from InDesign in EPUB 3 format in order to provide accessibility to all readers.
To learn more about EPUB 3 format and the built-in accessibility features, refer to the following free O'Reilly publications:
Before you get started with preparing the content in InDesign refer to these helpful guidelines:
- Top Tips for Creating Accessible EPUB 3 Files
- Inclusive Learning Design Handbook
- EPUB 3 Accessibility Guidelines
It is highly recommended for all to review the above mentioned guidelines. In summary, the following steps need to be completed:
Separate content and presentation
Visual reading is only one way of accessing content. Do not use visual-only cues such as coloured text, font size or positioning as the only clue to the meaning or importance of a word or section. Do not use tables or pictures of text to control the appearance of the content. The meaning of the content should be the same both with and without any styles or formatting applied.
Structure the content
Mark up each section in the document using appropriate styles (e.g. h1, h2..). Provide a correct hierarchy of sections and include page numbers.
Use images only for pictures, not for tables or text
Any content embedded in an image is not available to visually impaired readers. Use proper and complete markup for text and tabular data.
Use image descriptions and alt text
Every image should have a description, caption or alt text unless it is solely decorative.
MathML makes mathematical equations accessible to everyone by eliminating the ambiguity of a verbal / audio description of a picture. There are many tools available to support MathML creation.
Provide alternative access to media content
Make sure the native controls for video and audio content are enabled by default. Provide fallback options such as captions or descriptions for video and transcripts for audio.
The bottom line
- Adhere to standards
- Follow best coding practices
- Take care of non-textual content (images, video and audio)
The resulting output will be compatible with standard assistive technologies and accessible to people with visual, sensory and intellectual impairments.
The above guidelines need to be implemented using the tools available for InDesign. The Adobe InDesign Accessibility page has tutorials and videos to help you prepare the content in accordance with accessibility guidelines. Note that the tips for creating accessible PDF files are applicable for creating EPUB 3 files as well.
- Use the Mapping styles and tags features for semantic markup of the content. Assistive technologies such as screen readers rely on the styles used in the content to convey important information such as the presence of headings to the users.
- Use the Articles panel to organize your content by dragging images, text frames, and other content. Use this tool to control the sequence of text, images, and graphics in the exported document, ensuring it is optimized for accessibility.
- Add Alternative Text for Images so that non-visual users can understand the graphical content by reading the descriptions of images with assistive technology.
- Take care of metadata. Appropriate metadata is good for accessibility and search engine optimization.
- Export to EPUB 3
- Validate your EPUB 3 file: You can use the online EPUB 3 Validator maintained by IDPF to make sure that your EPUB 3 file does not have any errors. This site uses EpubCheck to provide validation information for documents in EPUB 2 and EPUB 3 formats. If you are creating commercial EPUBs in volume, you must install EpubCheck instead of using this site.
Text is available under the terms of the DAISY Consortium Intellectual Property Policy, Licensing, and Working Group Process.