Many problems in Computer Vision are formulated in the form of a random
field over discrete variables, such as Markov or Conditional Random
Field (MRF/CRF). Examples range from low-level vision such as image
segmentation, optical flow and stereo reconstruction, to high-level
vision such as object recognition. The goal is typically to infer the
most probable values of the random variables, known as Maximum a
Posteriori (MAP) estimation.
In this tutorial I will cover several algorithms for MAP-MRF estimation.
I will focus on techniques based on the dual decomposition
approach.
In particular, I will consider tree-reweighted message passing
and its precursor, max-product belief propagation.
I will also discuss an alternative subgradient ascent approach,
and illustrate it on some concrete computer vision problems such
as computing correspondences between sparse image features.
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