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Computer Examples by Michael Ross. Learning low-level vision. Ising model. Each location has a 50% chance of being 'up' or 'down'. There is a 60% chance that a location has the same value as one of its 8-connected neighbors.
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Computer Examples by Michael Ross Learning low-level vision
Ising model • Each location has a 50% chance of being 'up' or 'down'. • There is a 60% chance that a location has the same value as one of its 8-connected neighbors. • There is an 80% chance that the sensor at a location reports the correct spin.
Ising model Noise corrupted. Reconstructed. True scene.
Ising model with Gaussian noise Noise corrupted. Reconstructed. True scene.
Segmentation • An attempt to learn segmentation rules from examples. • Learn sensor models for each feature. • Construct an MRF with interconnected layers, one for each feature. • Allow individually insufficient features to exchange information.
Segmentation Signal: horizontal & vertical gradients. Scene: edge detected by motion.
Segmentation ...
Segmentation Signal: horizontal & vertical gradients. Scene: edge detected by belief propagation.
Segmentation • Issues: takes about 25 minutes to produce result (10 iterations). Why? Considers 100 possible candidates at each location -> ~36 million calculations per iteration. • Simple features are not very predictive at many locations - better features mean that we need to consider fewer candidates. • Benefit: learning reduces the number of assumptions and preconceptions.