Originally Posted by kiwidude
...Right now I know absolutely zero about the internals of an ePUB in terms of detecting a Calibre jacket but I'm sure if I looked into it or asked in the dev forum someone could give me a pointer. I know how to get the EPUB content (having done that for the Extract ISBN plugin), what I don't know is how to use that set of internal EPUB files to identify a jacket being amongst them. Perhaps there is a simple regex I can apply or similar. If anyone throws the answer at me I will add this sooner, otherwise I will put it on the list for a future release.