Many problems in computer vision can be modeled using
conditional Markov random fields (CRF). Since finding
the maximum a posteriori (MAP) solution in such models
is NP-hard, much attention in recent years has been
placed on finding good approximate solutions. In particular,
graph-cut based algorithms, such as -expansion, are
tremendously successful at solving problems with regular
potentials. However, for arbitrary energy functions, message
passing algorithms, such as max-product belief propagation,
are still the only resort.
In this paper we describe a general framework for finding
approximate MAP solutions of arbitrary energy functions.
Our algorithm (called Alphabet SOUP for Sequential
Optimization for Unrestricted Potentials) performs a search
over variable assignments by iteratively solving subproblems
over a reduced state-space. We provide a theoretical
guarantee on the quality of the solution when the inner
loop of our algorithm is solved exactly. We show that...