<http://schema.org/image>
<http://rack.2.mshcdn.com/media/ZgkyMDE0LzA0LzIyLzM3L0NvbG91cmJsaW5kLjQ3YjBmLmpwZwpwCXRodW1iCTEyMDB4NjI3IwplCWpwZw/93fccf79/b80/Colourblind-test.jpg>
<http://mashable.com/2014/04/22/web-designing-colorblindness/>