Invariant pattern recognition against defocus based on subband decomposition of the filter

The discrimination capability (DC) is an important quality parameter in pat tern recognition. If the input scene suffers some degradation, this paramet er decreases. A source of degradation could be the imaging system, in parti cular the obtained image could be out of focus. In this paper we analyze si ngle and multichannel methods to obtain a DC invariant to the defocus. They are based on the Laplacian pyramidal decomposition of the filter. In the c ase of multichannel procedures we analyze several nonlinear methods to comb ine the information given by each channel. (C) 2000 Published by Elsevier S cience B.V.