User-provided object bounding box is a simple and
popular interaction paradigm considered by many existing
interactive image segmentation frameworks. However,
these frameworks tend to exploit the provided bounding box
merely to exclude its exterior from consideration and sometimes
to initialize the energy minimization. In this paper, we
discuss how the bounding box can be further used to impose
a powerful topological prior, which prevents the solution
from excessive shrinking and ensures that the user-provided
box bounds the segmentation in a sufficiently tight way.
The prior is expressed using hard constraints incorporated
into the global energy minimization framework leading
to an NP-hard integer program. We then investigate
the possible optimization strategies including linear relaxation
as well as a new graph cut algorithm called pinpointing.
The latter can be used either as a rounding method
for the fractional LP solution, which is provably better
than thresholdin...