There are a lot of apps in Facebook that does weight the friendships and generated images. Maybe one of them have their algorithm opened and you may use it to improve the accuracy.
I'll rephrase that: adding a weight to an edge is not hard, I actually having several heuristics on hand to do that. It's just really time consuming the first time you do it, because you have to load a lot of data in order to be accurate. Moreover it requires additional permissions, which I'd rather avoid.