I guess you could figure that out yourself as it's really not that hard : take your scope layer in photoshop and make sure the parts you want to be transparent are transaprent in the layer then go to filters/xnormal/dilation , a dialogue asking for a radius will open , pick that radius depending on your resolution I wouldn't go over 16 px with a 1024² texture , hit okay or apply and the filter will clone all border pixels of oyur layer 16 times around the visible parts to create a border this is also called "edge padding"