Full path for background image

[fernandoc1]

I'm trying to customize Gravstrap and I have the following issue:
The background of the main page is given in the following line of code:
[g-jumbotron name="jumbotron1" fullwidth="true" image="bg_home.jpg" render=false]
However, I would like to change the image path, to an absolute path from another server, like this, for example:
[g-jumbotron name="jumbotron1" fullwidth="true" image="http://serverimage.com/bg_home.jpg?params=1234" render=false]
But it is not working...
Can someone help me?