Fast Transformation-Invariant Component Analysis

  • Authors:
  • Anitha Kannan;Nebojsa Jojic;Brendan J. Frey

  • Affiliations:
  • University of Toronto, Toronto, Canada;Microsoft Research, Redmond, USA;University of Toronto, Toronto, Canada

  • Venue:
  • International Journal of Computer Vision
  • Year:
  • 2008

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Abstract

Dimensionality reduction techniques such as principal componentanalysis and factor analysis are used to discover a linear mappingbetween high-dimensional data samples and points in alower-dimensional subspace. Previously, Frey and Jojic introducedtransformation-invariant component analysis (TCA) to learn a linearmapping, invariant to a set of known form of globaltransformations. However, parameter estimation in that model usingthe previously-proposed expectation maximization (EM) algorithmrequired scalar operations in the order of N2where N is the dimensionality of each training example. Thisis prohibitive for many applications of interest such as modelingmid-to large-size images, where, for instance, iN may be ashigh as 786432 (512×512 RGB image). In this paper, we presentan efficient algorithm that reduces the computational requirementsto order of NlogN. With this speedup, we show theeffectiveness of transformation-invariant component analysis invarious applications including tracking, learning video textures,clustering, object recognition and object detection in images.Software for TCA can be downloaded from http://www.psi.toronto.edu/fastTCA.htm