MRFs (X1,X2) 1 2 3 X3 X1 X2 4 (X2,X3,X3) X4

CRFs Image I (X1,X2,I) 1 2 3 X3 X1 X2 4 (X2,X3,X3,I) X4

Examples X = Image patches X = Patches on a regular lattice [Quattoni et al.] MRF CRF X = Patches on a regular lattice [Kumar]

Examples X = pixels, regions, image [He et al.]

Issues Inference Learning Easy only when the planets are aligned Approximate solutions only  How good are they? Learning Difficult and slow Limits the complexity of the models

Issues Generality Global label inference Can use arbitrary models but limited to restricted models in practice because of inference and learning challenges Global label inference Inference over global labeling of the data in theory, but limited propagation across image in practice Support limited by the complexity of learning and inference Use of complex graph and clique structure is difficult