Turning a print book into an eBook is not just about obtaining rights from the author and learning how to format for the Kindle store, it can also require obtaining rights to images and artwork.
Digital Book World explains in more detail: “There’s nothing inherently tricky about images. They are intellectual property, subject to the same copyright regulation as any other. It’s just that a standard biography, for example, can contain images from dozens of different sources, each included in the book under a slightly different agreement depending on where it came from (the subject’s family, historical archives, a stock photography agency). If you are a nonfiction publisher, that means creating ebook editions of your backlist will involve not just the usual author wrangling but also digging through hundreds of contracts for individual photographs and illustrations.”
While it may slow up the process to go back over contracts looking for photo rights, it might also be an opportunity for publishers to go back and see what other kind of media exists. If there are additional photos or if there is even video, it might make sense for a publisher to enhance the eBook with this media content, or to create new content that is updated from the print edition.