I am having a similar problem, hopefully this reply will bump this thread up!
I'm designing an ebook which has about 120 images. So far it's been published for Kindle and as an epub elsewhere. The images are an adequate size in those formats and readers, though compromised some for quality so the book size is not massive. It previews fine on nook for PC, but the images come out TINY on nook for iPad. And there is no zoom feature in the nook! This is a technical book and the images are important to the content.
The same book file on the same iPad looks fine in BlueFire, iBooks, and Kindle. Why is nook on the iPad rendering these images so small, and what can I do about it? Short of the nuclear option of replacing all images with larger versions, if I have them, and making a massive file...
Thanks in advance!