Desktop Background Group policy

Hi all,

I have configured  GP in such a way that all of the domain users are getting this background imageonce they are logged in the network. Since we are a consultancy firm, users are always roaming outside and at that time they are getting black screen since machine cannot contact the server. I tried to put the image in the local drive which is also getting the same results. Am using Windows 2008 R2 and Win 7 x64 enterprise as client. is there a way to save these backgrounds and display it even outside office ?

Configurations are like this

Under user configuration->Policies->Admin Templates->Control Panel->Desktop (provided path here)