can i ues that for instance segmentation?

[Jackandrome]

it works for a image instance segmentation in which you dont kown how many classes ?

[Borda]

Sure, there are several publications to do so. We refer a couple of them in "1.2 Other related methods" in
Region growing using superpixels with learned shape prior

some applications you can find also here:

• sample function object_segmentation_graphcut_slic(...)
• ipython notebook egg_segment_graphcut.ipynb