Margin-based discriminant dimensionality reduction for visual recognition

Nearest neighbour classifiers and related kernel methods often perform poorly in high dimensional problems because it is infeasible to include enough training samples to cover the class regions densely. In such cases, test samples often fall into gaps between training samples where the nearest neighbours are too distant to be good indicators of class membership. One solution is to project the data onto a discriminative lower dimensional subspace. We propose a gap-resistant nonparametric method for finding such subspaces: first the gaps are filled by building a convex model of the region spanned by each class ? we test the affine and convex hulls and the bounding disk of the class training samples ? then a set of highly discriminative directions is found by building and decomposing a scatter matrix of weighted displacement vectors from training examples to nearby rival class regions. The weights are chosen to focus attention on narrow margin cases while still allowing more diversity an...

• Type: Conference
• Year: 2008
• Where: CVPR
• Authors: Hakan Cevikalp, Bill Triggs, Frédéric Jurie, Robi Polikar
• Keywords: Class Training Samples, Computer Vision, CVPR 2008, Dimensional Reduced Space, Lower Dimensional Subspace, Nearest Neighbours, Rival Class Regions