Well, in the span of a week or so I now have two Nooks, a Nook Simple Touch (the current generation cheapest Nook), and a first generation Nook, generously donated by a friend at church. Even though I’ve spent a considerable amount of time formatting the MOBI (Kindle) version of the fractal book, the Nook presented some unique challenges which required different solutions. Below are my initial findings:
1. Use a different file: The Nook version is a little different than the Kindle version of an eBook, particularly one like mine with graphics, figures and equations. For a text eBook you may be able to get away with a single Word file, but in my case you need two, one for your MOBI draft, and one for your EPUB.
2. Size is everything: The Nook, especially the Nook android app, is not always the best at resizing graphics. On the Kindle, if an image is 8″ wide, beyond the physical extents of the device, it is auto-shrunk and centered. This is not the case with the Nook. Above 5″ or so you run the risk of the edges of your picture being cut off (more than 6″ on the eReader Nook).
3. Simplify Math: Probably the worst place where the Nook cuts off graphics is equations. The equation editor in Word produces a graphic file for each equation (usually PNG). Since the equation is not treated as a graphic in Word, however, it is not easy to adjust its width and the edge of the equation can be cut off if it’s too long. Reducing the font or changing from display to inline can both help, but the solution I’ve found best is to shorten words. Instead of maximum use max, instead of number use num, iteration is iter, etc. Creating a multi-line equation may help in some circumstances as well. The eReader version of the Nook is better (but not perfect) at handling this problem.
4. Eliminate Transparency: And while we’re on the subject, equations will be unreadable in the first place because of the transparency in PNG. The Kindle format (MOBI) handles transparency without difficulty (at least the newer generation Touch, Fire and app do). On the Nook it’s a different story. The first time I converted directly to EPUB from the “web page filtered” file all of my equations were black rectangles. The simplest solution I found was to first convert the book to MOBI, then convert this MOBI file to EPUB. The conversion process to MOBI must eliminate transparency so the EPUB doesn’t encounter it. (This is using Calibre).
5. Header in the right direction: The older generation Nooks (and possibly Kindles) do not have the same range of fonts as newer eReaders. In particular headers or section titles that were bold and a little larger do not render correctly. This can affect the flow of pages. No specific fix, just something to be aware of.
6. Spell out fractions: The EPUB format does not seem to recognize fraction characters like ½. Invalid characters are replaced with a rectangle. My suggestion is to spell fractions out, for example one-half or (1/2).
7. PDF behavior: PDFs can often be a great solution for solving some of the inconsistencies of an eBook format, but a PDF does not look the same on every eReader. The Kindle auto-centers each page, vertically and horizontally. This can be annoying if a page has only a single paragraph though you can eliminate vertical centering by adding page numbers at the bottom of each page. On the Nook PDFs are left oriented, meaning there is often a lot of white space on the right hand side. A possible solution is a PDF sized specifically for the Nook, using pages that match its dimensions.
8. A Page is not a page: My book is 430 or so pages on the Nook, 500ish in Word, and 300ish on the Kindle. Don’t sweat the page numbers too much, they’ll never match.
9. Use Helevetica Nueue as your font: Pretty self explanatory. This gives the most consistent look across all generations of the Nook and Kindle. Some apps may not support this, but they’ll support something similar. Your Word Doc doesn’t need to be in this font, so long as your reader is set to it. Many computers may not actually have this font installed (and its not free).
10. Webpage links may not work: The Nook Simple touch does not have a web browser so none of my URLs work in the eBook for getting to reference websites and software. Make sure to spell out URLs so your readers can type them, or possibly make them available on your blog or website.
That’s all for now, may have more later.
[BTW] : Ben Trube, Writer 