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In the last few years many technology blogs have been participating in “National Blog Posting Month,” a play off the more famous National Novel Writing Month.

Threepress is participating: we’ll be posting ebook technology tips, code samples and updates on our projects every day for the whole month of November. Hopefully we’ll include some guest bloggers as well as some posts from individuals who’ve worked on Threepress projects.

I’ll start off with five tips for ebook conversion.

Try the Calibre command-line tools

If you’re a developer or just impatient you’ll probably prefer to use the command-line tools included in Calibre rather than the main GUI application, which can be slow to start up and quick to crash. Many people don’t realize they’re available, but they’re great for one-off conversions or embedding in other applications. The most useful tool is the one-stop shop ebook-convert (older versions of Calibre had individual scripts for different formats).

The complete list and documentation for all the Calibre command-line tools is available from the Calibre site.

Prefer InDesign to Word, Word to PDF

If you have an InDesign original and at least version CS4, definitely start by creating an ePub from it. You’ll still need to do some hand-work in most cases, but it will save a lot of effort.

Word has its problems, but it’s more easily converted to a reflowable format than PDF. If you have only those two, start with the Word file. I’d probably do Word->RTF->ePub, with the last step in Calibre.

Convert from more complex formats to less complex ones

Mobipocket has simpler markup than ePub. We recommend that if you need to produce both formats you make the Mobipocket from the ePub file, rather than the other way around. XHTML in ePub is a more rich expression language than what’s available in Mobi, and is less likely to lose formatting details.

Test in multiple devices and form-factors

When we test ePub books we’ve created, this is our go-to list of readers:

  1. Bookworm
  2. Adobe Digital Editions
  3. Smartphone reader (Stanza on the iPhone)
  4. e-ink device (Sony Reader)

We usually start with Bookworm running under Firefox; you’ll get the best CSS debugging that way, especially when using Firebug.


Most people working with the ePub format are aware of the EpubCheck validator created by engineers at Adobe. (The web-hosted epub validator on the Threepress site is by far our largest driver of traffic.) But I mention it again because it’s important! Peter Sorotokin from Adobe has been committing changes recently, so this is a good time to get any requests or bugs into the issue tracker.

Later this month we’ll have some interesting updates to the Threepress version of the validator that should make checking easier and more thorough.

(Edited Nov 1 to reflect updated information about Calibre tools)


3 Responses to “Five ebook conversion tips”

  1. Marshall Vandegrift

    Somewhat recently, the calibre command-line conversion tools were reduced down to just “ebook-convert.” Its usage is a bit counter-conventional (alas), but the switch represents an internal re-architecture to a single internal model of a book, which should improve conversion in the long run.

  2. Marshall Vandegrift

    P.S. Maybe it’s just me, but the font-size for the blog part of the Threepress site looks unintentionally large. Maybe 20pts or so for body text? Certainly larger than the Threepress front page.

  3. liza

    Marshall: Thanks, I updated the post and I’ve corrected the styles to be more sane. (I had local settings in Firefox that were interfering).