Originally Posted by gonzule
I know that the ePub format is just a bunch of zipped files that belong to the book. I just wanted to know how compressed this files are in .zip . Can I compress them a lot to save space ir they'll be unreadable by the device ?(for me its a sony reader 505)
With the exception of the mime-type all of the files are compressed using zip standard compression generally. Of course images are often already compressed so the difference isn't high but the text is compressed a lot. You can try a higher compression number if you wish and the zip you use supports it but don't expect to save a lot.