1. How to and how not to use graph cuts
Karen Liu and Brett Allen

2. What graph cuts is good for
Suppose you want to label the nodes in a graph:
For each node, you have:
a data term: D(p, fp) – the cost of labeling node p with label fp
a neighbor term, V(fp, fq), the cost of labeling connected nodes p and q with labels fp and fq.
You want to minimize:

3. The algorithm we used an existing min-cut implementation
for each α-expansion, we build a graph that expresses the desirability of switching each node’s label to α ( ):

4. Application 1: Stripe labeling
A harder case

5. Using graph cuts

6. Results

7. What went wrong?! True labeling: … 11 12 13 14 15 16 17 18 19 …
Current labeling: … …
…any α-expansion will not improve the energy!
α-expansion only works if:

8. Application 2: Stereo

9. Using graph cuts

10. Results Ground truth Graph cuts
Parameters: 12 labels (12-34 pixel displacement), w = 10

11. Results

12. Results (2)
Input
Graph cuts
Ground truth

13. Results (3)