I recently bought an ebook online (DRM-free). It was supposed to be in epub format, which it technically is, but as it turns out they just packaged an image of each individual page rather than the actual text. As result the whole thing is around 100MB and does not work on any of my readers. The only way to read it at the moment is to extract it and use an image viewer.
How can I convert this to actual text to make it usable?