Fast and Compact Graph Cuts for the Boykov-Kolmogorov Algorithm
For computer vision practitioners needing fast, memory-efficient graph cuts, this paper provides a practical improvement over the standard BK algorithm.
The paper improves the Boykov-Kolmogorov algorithm for minimum s-t cut, achieving O(m|C|) time complexity and enabling cuts on graphs with up to 10^9 vertices and 10^10 edges on a 128 GB machine, with the fastest available implementation on benchmarks.
Computing a minimum $s$-$t$ cut in a graph is a solution to a wide range of computer vision problems, and is often done using the Boykov-Kolmogorov (BK) algorithm. In this paper, we revisit the BK algorithm from both a theoretical and practical point of view. We improve the analysis of the time complexity of the BK algorithm to $O(mn|C|)$ and propose a new algorithm, the fast and compact BK (fcBK) algorithm, with a time complexity of $O(m|C|)$, where $m$, $n$, and $|C|$ are the number of edges, number of vertices, and the capacity of the cut, respectively. We additionally propose a compact graph representation that allows our implementation to find a minimum $s$-$t$ cut in a graph with upwards of $10^9$ vertices and $10^{10}$ edges on a machine with 128 GB of memory. We find our implementation of the BK algorithm to be the fastest available implementation of the BK algorithm when evaluating on a comprehensive set of benchmark datasets, highlighting the importance of memory-efficient implementations. We make our implementations publicly available for further research and implementation development within minimum $s$-$t$ cut algorithms.