There is no setting in the "
com.apple.ibooks.display-options.xml" that controls the display size of the images.
Code:
<?xml version="1.0" encoding="UTF-8"?>
<display_options>
<platform name="*">
<option name="specified-fonts">true</option>
<option name="interactive">true</option>
<option name="fixed-layout">true</option>
<option name="open-to-spread">true</option>
</platform>
<platform name="iphone">
<option name="orientation-lock">landscape-only</option>
</platform>
</display_options>
Display size of the images are usually controlled via CSS or inside the XHTML in the IMG tag.
iBooks usually displays images in full bleed if the actual image size is larger than the iPad's display size,
IF there is no CSS controlling it.