I know this is an old thread but I have a similar issue with an ebook I'm converting. The book has a half title page with a title page following it. Both are full-screen images. Either one of these will display fine by themselves with no blank page afterward. However, when I put them both in the ebook, one following the other, there is a blank page between them. Most of my conversions have a full-screen image as the title page and when I'm only working with one image, everything is fine. I only run into this when I have back-to-back images. They are in separate html files.
This isn't a comic and there are only the two images so no sort of cbz conversion would help me.
Same issue? Any ideas?