
Stefan Roth
TU Darmstadt, Germany
Monday 27 October 2008
15.00
Seminar Room B10 (Basement)
Alexandra House, 17 Queen Square, London, WC1N 3AR
HighOrder Markov Random Fields for LowLevel Vision
I will introduce several lowlevel vision tasks and show how they can be approached in a unified way as Bayesian inference problems. One key component of these Bayesian approaches is modeling the prior distribution. In image restoration applications, for example in image denoising, this amounts to modeling the prior probability of observing a particular image among all possible images. I will review Markov random fields (MRFs) and show how they can be used to formulate image priors. Past MRF approaches have mostly relied on simple random field structures that only model interactions between neighboring pixels, which are not powerful enough to capture the rich statistics of natural images. In my talk I will introduce a new highorder Markov random field model, termed Fields of Experts (FoE), that better captures the structure of natural images by modeling interactions among larger neighborhoods of pixels. The parameters of this model are learned from a database of natural images using contrastive divergence learning. I will demonstrate the capabilities of the FoE model on various image restoration applications. Furthermore, I will show that the FieldsofExperts model is applicable to a wide range of other lowlevel vision problems and briefly discuss its application to modeling and estimating optical flow.