This is a caveat – and I'll start it with a true and really grumpy statement: I hate working with iTunes. Amazon and B&N are angels next to iTunes.
Caveat: iTunes has put a deep and heartfelt limitation on images of any kind. Therefore, when you use the object export options box in order to preserve the layout and/or aesthetic effect of certain fonts in your titles or whatever – you have to be absolutely certain that you do not exceed the pixel number limit (one million per or two, I'm still not solid on that number – 1, I think). If you do, your package will NOT be delivered. If you get the email that damns your upload (it will come several minutes after you've celebrated because it SEEMED to be accepted), the email will inform you that certain images have exceeded the limit. These images will have file names you won't recognize, as they were assigned during export and packaging.
If you open the epub in something like Springy, you can easily navigate to the image file and identify the images in question. At that point, it's back to square one – you need to go back to those pages, be sure you have not selected 300 dpi as the size of the images in the options box, and try again. I actually double clicked on the image in the Springy-open menu, which allowed me to open the images in PS, where I checked the image size. All you have to do is multiply height px by width px to see if you are over the limit.
I did not save the image at that point, afraid of messing up the manifest. I close Springy without making any changes, and I went back to the object export options box in the indd file and selected 150 dpi, which put me under the limit. Considering the resolution of the readers we use at present, I can't see that the diff in dpi will make any diff.
Then you go back into iTunes Producer (which you have downloaded into your applications folder), OPEN the package you have already established for this book, navigate to assets and re-upload your book file. If you don't hear from Apple within the hour, you might be all right.
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