On last week’s class, we have talked about the ePub format, I have also worked on a project to create a software which convert PDF files to ePub. For this reason, I would like to introduce more details on this e-book format in this article.
What is ePub ?
Wikipedia definition : “EPUB (short for electronic publication; alternatively capitalized as ePub, ePUB, EPub, or epub, with “EPUB” preferred by the vendor) is a free and open e-book standard by the International Digital Publishing Forum (IDPF). Files have the extension .epub.”
A ePub file can have actually two different types of content. The first type is reflowable content, meaning that an ePub reader can optimize text for a particular display device. The example showed on the course is a reflowable content ePub file. This kind of content permits user and ePub reader to adjust size of text. The second type of content is called fixed-layout content, in which the electronic book is more like a traditional book, positions of texts and images are relatively fixed to the page. A fiexed-layout ePub file looks exactly like a real book.This type of content is more preferred by editors who require high reading quality and more interaction between the reader and the machine (ipad for example).
Here is an example of a fixed layout ePub file
Standards of ePub
The International Digital Publishing Forum (IDPF) is the global trade and standards organization dedicated to the development and promotion of electronic publishing and content consumption. The key IDPF standard is EPUB®, the current version is EPUB 3.0.
EPUB is 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, font files, and other resources — for distribution in a single-file format.
EPUB 2 was initially standardized in 2007 as a successor format to the Open eBook Publication Structure or “OEB”, which was originally developed in 1999. A maintenance release, EPUB 2.0.1, was approved in 2010. In October, 2011, EPUB 3 was apprvoed as a final Recommended Specification.
Evolution of ePub : new functions on the ePub 3.0
EPUB 2 provides all the formatting and layout capabilities of HTML4 and CSS2, which is more than sufficient for text-heavy publications. However, publishers and authors found that EPUB 2 couldn’t handle many content types and use cases, such as multimedia books, books with complex layout, mathematical publications, and interactive documents. The IDPF and eBook community released the specification for EPUB 3 in October, 2011.
- The required schema for EPUB 3 content documents changed from XHTML 1.1 to the XHTML serialization of HTML5. It was a critical requirement to include the multimedia elements from HTML5 (<video>, <audio>, and <canvas>).
- The allowable range of CSS in EPUB 3 content documents expanded from a subset of CSS2.1 to a set of mature modules from CSS3 relevant to document authoring.
- MathML was added to XHTML5 and SVG as a first-order content type.
- Support for embedded fonts is now required of reading systems that have a CSS viewport. Web Open Font Format was added as an acceptable font format.
- Explicit support for non-Western writing modes and scripts, including vertical layout in Japanese and other Asian scripts.
Here is an example of video in Epub 3.0 file
Softwares and Devices to read ePub files
Since ePub is a open standard electronic book format, all companies or individual who are interested in producing a ePub software or a ePub file can do it with all instructions published on the Internet. I will list some pratical ePub reading softwares/applications on all sorts of devices.
ibooks : an e-book application by Apple Inc.
Windows and unix/mac os :
adobe digital edition : software made by Adobe, designed for all operating systems, but DO NOT support fixed-layout content.
Ireader, Mantano : Apps available on Android Market.
Chrome/firefox extension :
dotEPUB/EPUBReader : extensions of web browsers that make it possible to easily read a ePub file with widely used web browsers. Simple to use, but not very stable
Softwares to create easily ePub files
There are several free ePub creators on the Internet. They are really easy to use and with these softwares, you don’t need to understand all those ePub standards or mechanism of how it works. All you need is to put images and texts at the right palce. There are two popular softwares:
calibre : free and open source e-book computer software that organizes, saves and manages e-books, supporting a variety of formats. It supports ios, kindle, kobo, etc.
eCub: a cross-platform tool for creating EPUB and MobiPocket books.