Alexander Shekhovtsov

Learn More
We consider the problem of optimizing multilabel MRFs, which is in general NP-hard and ubiquitous in low-level computer vision. One approach for its solution is to formulate it as an integer linear programming and relax the integrality constraints. The approach we consider in this paper is to first convert the multi-label MRF into an equivalent binary-label(More)
We propose a novel MRF-based model for deformable image matching (also known as registration). The deformation is described by a field of discrete variables, representing displacements of (blocks of) pixels. Discontinuities in the deformation are prohibited by imposing hard pairwise constraints in the model. Exact maximum a posteriori inference is(More)
We propose a novel distributed algorithm for the minimum cut problem. Motivated by applications like volumetric segmentation in computer vision, we aim at solving large sparse problems. When the problem does not fully fit in the memory, we need to either process it by parts, looking at one part at a time, or distribute across several computers. Many(More)
Most image labeling problems such as segmenta-tion and image reconstruction are fundamentally ill-posed and suffer from ambiguities and noise. Higher order image priors encode high level structural dependencies between pixels and are key to overcoming these problems. However, these priors in general lead to computationally intractable models. This paper(More)
We propose a novel MRF-based model for image matching. Given two images, the task is to estimate a mapping from one image to another, in order to maximize the matching quality. We consider mappings defined by discrete deformation field constrained to preserve 2-dimensional continuity. We approach the corresponding optimization problem by the TRW-S(More)
—We consider the NP-hard problem of MAP-inference for graphical models. We propose a polynomial time and practically efficient algorithm for finding a part of its optimal solution. Specifically, our algorithm marks each label in each node of the considered graphical model either as (i) optimal, meaning that it belongs to all optimal solutions of the(More)
In tests of "illuminated area" and the "threatening situation" avoidance by rats, apomorphine and phenamine, administered intraperitoneally, attenuate the state of alarm. A similar effect is observed when sulpiride, a selective blocker of D2-receptors of dopamine, and of picrotoxin, a GABA antagonist, are administered. Sulpiride effectively counteracts the(More)
We address the problem of energy minimization, which is (1) generally NP-complete and (2) involves many discrete variables – commonly a 2D array of them, arising from an MRF model. One of the approaches to the problem is to formulate it as integer linear programming and relax integrality constraints. However this can be done in a number of possible ways.(More)