Making the image 2048 x 1536 will exceed the page.
Sorry, the size I gave is the screenshot size and iPad screen size - which equals the 3.2million max image size allowed.
I use my images this size because in my Photo books.. I do not use images full ( iBA) page size.
You may find when running a preview on iPad that the iBA page size with a full size image - that the tap to magnify to screen size does not work.
Photographers want images with high resolution to make a sharp, crisp image, the Retina screeen resolution is 264, so processing to 300-350ppi is not needed and makes no difference.
Previoulsy when I suggested to others to use a resolution of 264 - I was constantly being scolded by a long serving group memember who insisted that resolution above 72pp not needed and simply "bloated" the image.
My opinion was that if I matched the screen resolution of 264 for Retina screen - it was optomised for the screens capabilities.
The asset guide states:-
Optimizing Images in Fixed Layout Books
In addition to the image recommendations in “Interior Image Requirements” (page 24), the following apply
to working with images in Fixed Layout books:
● Images inside Fixed Layout books must be in JPEG or PNG format. To reduce file size, use JPEG for any
images that do not require transparency. Using JPEGs results in a smaller file size and better performance.
We recommend using a quality of 85 for JPEGs.
● Images inside Fixed Layout books must not exceed 3.2 million pixels. You can calculate whether an image
inside the book file exceeds 3.2 million pixels by multiplying the height and width of the image