<http://schema.org/image_url>
"http://media.mlive.com/saginawnews/photo/2014/01/-0eee2345879a66a9.jpg"^^<http://www.w3.org/2001/XMLSchema#string>
<http://photos.mlive.com/4473/gallery/frogs_a_chorus_of_colors_at_th/index.html>