the Image field stores a reference to a Sitefinity image using a ContentLink, this ContentLink is what is actually stored in the property.
You can expand the content link to get the image with a helper method, as described here: http://www.sitefinity.com/blogs/joshmorales/posts/josh-morales-blog/2012/01/19/retrieving_data_from_dynamic_modules_using_the_module_builder_api
I hope this is helpful!