djvu

Conversions from Ebook (AZW, CHM, MOBI) to Electronic Publication (EPUB): Page Setup Output Profile: "Generic e-ink HD." Maintains original resolutions of images

Admittedly not the best UX, but as far as I've found the most atomic configuration options by a country mile. The ability to load font files into storage and use them to render the book text and manage font size to the 1/10th of a point is pure joy. I mean, really, what could be more important than being...