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Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-7557-4904
2010 (English)In: Proceedings SSBA 2010, 2010, 19-22 p.Conference paper (Other academic)
Abstract [en]

We investigate several topics related to manifold-techniques for signal processing. On the most general level we consider manifolds with a Riemannian Geometry. These manifolds are characterized by their inner products on the tangent spaces. We describe the connection between the symmetric positive-definite matrices defining these inner products and the Cartan and the Iwasawa decomposition of the general linear matrix groups. This decomposition gives rise to the decomposition of the inner product matrices into diagonal matrices and orthonormal and into diagonal and upper triangular matrices. Next we describe the estimation of the inner product matrices from measured data as an optimization process on the homogeneous space of upper triangular matrices. We show that the decomposition leads to simple forms of gradients and Hessian matrices that are commonly used in optimization algorithms. Using the parametrization from the symmetric space ensures also that all intermediate estimates of the inner product matrix are symmetric and positive definite. Finally we apply the method to a problem from psychophysics where the color perception properties of an observer are characterized with the help of color matching experiments. We will show that measurements from color weak observers require the enforcement of the positive-definiteness of the matrix with the help of the manifold optimization technique.

Place, publisher, year, edition, pages
2010. 19-22 p.
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-67277OAI: diva2:409122
SSBA symposium 2010
Available from: 2011-04-07 Created: 2011-04-07 Last updated: 2016-08-31

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Lenz, Reiner
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