Originally Posted by davidfor
The Kobo Touch/Glo/Mini driver in calibre has options to generate the cover images and send them to the reader when it sends the book. The cover images are generated from the calibre metadata and are stretched so there won't be any bars down the sides. This only works for books in the main memory. Also, it only generates the images that are appropriate for the firmware version.
If it dumps all the images in the .kobo/images folder, then it won't be able to store enough images for a large library of books as there is a limit to how many files are permitted in the images folder (7-8000ish as I recall). This is what I was doing originally, but with 3000 books, and 3 images needed for each, it was over the limit of allowed images.