Why does image url need to have request.scheme?

Question

We are getting this error in our pages. We can do a simple check and implement the request.scheme(which we are in the process of implementing) but w3.org states that resources can have relative schemes. Isn't og:image is similar to an image tag and should support all the features of an image tag.

Error:

Object at URL 'http://www.slideshare.net/jessedee/100-bullet-points-from-cannes-lions-2012' of type 'slideshare:presentation' is invalid because the given value '//cdn.slidesharecdn.com/100bulletpointsfromcanneslions12-120626070638-phpapp02-thumbnail-2?1340766735' for property 'og:image:url' could not be parsed as type 'url'.

Answer 1

The value for Facebook's og:image meta tag can't be protocol relative, it must be absolute