I do not know of any built-in option that does support this, but once I found the file names of the image files by opening a copy of the .iba file in a text editor that lets you view binary files, for example in Aquamacs Emacs. The image filenames will clearly stick out, even if all other content is a mess:
For example, searching for jps:

Or even simpler, use the Terminal to dump the iba-file with "strings" and search with "grep" for ".png":
Enter this line: (replace the red line by the path to a copy of your iba file)
strings ~/Documents/myDocuments/iBooks/Rezepte.iba | grep ".png"
this found:
Classic_Glyph-1.png
Classic_Glyph-1.pngPK
or
strings ~/Documents/myDocuments/iBooks/Rezepte\ copy.iba | grep ".jpg"
Beim Abschiedsdinner, Kobe.jpg
Colored_paper_backgrounds-1.jpg
92837758a-1.jpg
92818816b-1.jpg
Light-parchment-paper_a-1.jpg
Am Lake Chuzenchiko, Nikko.jpg
Weinprobe mit Chianti Classico.jpg ....
To create the pathname to your file you can simply drag it from the Finder into the Terminal window after typing "strings ".
Regards
Léonie