This task could be done using Sigil, but there is another tool uniquely suited to browsing through multiple EPUBs and checking out their inner workings–allow me to introduce Calibre:Ĭalibre is a Free software ebook management system–basically it does everything you could possibly want to do with an ebook… It manages your library and metadata, converts formats, syncs with devices, and has a built in reader and online book search. So I decided to look inside professionally published EPUBs to see what they were doing–reverse engineering!

I read a lot of information about how to deal with this issue, but I had trouble finding anyone who clearly and definitely communicated a solution. For example, EPUB formatting expert Liz Castro explains intricacies of the img tag in relation to iBooks in a post from 2011. Getting it right across platforms is complicated. This is slightly more complicated than it sounds, since it is not just about using the correct HTML tags–you also have to ensure that ereader devices will play nice with them. Instead, we want the image to flexibility resize to fit any screen. But, unless you actually put something in the tag you can not be sure… Since the average ereader screen is only around 600 x 800 pixels, many of the illustrations I added will likely run off the screen, looking something like this: Now, for many ereader devices and applications, illustrations inserted this way will display just fine–the application automatically resizes all images to fit on the screen. For example, how big should the image be? Does the text wrap? Does it get its own page? etc. However, you will notice that there is nothing in this set of tags to tell the ereader how how to handle the image. In the example above, the ereader looks for an image called “aladore_01.jpg” in the “Images” directory of the EPUB package. The HTML is just like a web page, the img tag tells the ereader to display an image and gives the relative location for the file. If we take a peak at the HTML contained in the EPUB, each image looks like this: In an earlier post, I popped Aladore’s illustrations into the EPUB using Sigil with out any clever formatting.

Calibre ebook images