I wonder whether an easier solution than opening up your book might be to add the line below to the "Kobo_eReader.conf" file located in the directory .kobo\Kobo\Kobo_eReader.conf in your reader. It is a text file, so you can edit it with any text editor. Here is the line you have to add:
To see what it can do to an epub page with images, see the screenshots in post 23
here