I have been testing the the boykov_kolbogorov_max_flow function in the previous weeks and I have a question that I can't seem to find the answer myself. I asked for it on StackOverflow [1] but nobody answered.

Can someone tell me why I get three classes (groups) instead of two? I always get class '0' and '4', and '1' on some cases. I thought a Graph Cut was supposed to output only two classes, so what's the meaning of '1'? Please read the SO question in [1] for more details. Thanks for your time.

Nil Goyette