### X. Zhang, D. S. Pham, W. Liu, and S. Venkatesh.
Optimal metric selection for improved multi-pose face recognition
with group information.
In *Proceedings of the IEEE International Conference on Pattern
Recognition (ICPR)*, Tsukuba, Japan, 2012.

We address the limitation of sparse representation based classification
with group information for multi-pose face recognition. First,we
observe that the key issue of such classification problem lies in
the choice of the metric norm of the residual vectors, which represent
the fitness of each class. Then we point out that limitation of the
current sparse representation classification algorithms is the wrong
choice of the L2 norm, which does not match with data statistics
as these residual values may be considerably non-Gaussian. We propose
an explicit but effective solution using Lp norm and explain theoretically
and numerically why such metric norm would be able to suppress outliers
and thus can significantly improve classification performance comparable
to the state-of-arts algorithms on some challenging datasets.

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