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Challenges in Computer Vision. Understanding the ”seeing machine” The input (images) The output (shapes, actions?, diagnosis?) The mapping (statistics, learning) The computation (algorithms). Shapes. Computation. Statistics. Images. Fundamental problems.
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Challenges in Computer Vision Understanding the ”seeing machine” • The input (images) • The output (shapes, actions?, diagnosis?) • The mapping (statistics, learning) • The computation (algorithms) Shapes Computation Statistics Images
Fundamental problems • Input space is high (infinite) dimensional • Modeling of shape • Mapping is nonlinear • Generalization from few examples • Finite memory and computational time
Fundamental challenge Computational efficient, statistical optimal mapping from images to models/actions: The optimal mapping is unreachable (Kolmogorov) Infinite computation time using optimal mapping (Ryabko) So only hacking is left, so let’s hack Only theories that proove themselves in practice are good theories
Desired properties • Generalisation -> metric in input and model space • Universality -> Flexible/scalable models • Fast convergence -> ”least committed priors” and ”good learning”
Concrete challeges • Statistical well-founded metric on images • Geometrical metrics on shapes • Universal shape models • Information reduction or ”visual attention” • Marginalisation over hidden model parameters • Computational efficient approximative methods • Statistics on trees/graphs
Metrics on images • Scale-space • Independent component analysis • Geometry of images
Metrics on shapes • Shape-space theory • Grenander’s ”Theory of shape” • Invariant parametrisations • Brownian motions • Warps of embedding spaces • Lie-group methods
Universal shape models • Fourier descriptors • Landmark representations • Medial models • Level sets
Information reduction • Dimensionality reduction • Feature selection • ”AdaBoost”
Marginalisation over hidden parameters • Common sense • Mean field analysis?
Computational efficient methods • PDEs • Particle filters • Hierachical representations • Sequential testing