SYNTHETIC DISCRIMINANT FUNCTION FILTER EMPLOYING NONLINEAR SPACE-DOMAIN PREPROCESSING ON BANDPASS-FILTERED IMAGES

Previously [Appl. Opt. 36, p. 9212 (1997)] we examined the performance of the linear and nonlinear preprocessed difference-of-Gaussians filt er, and it was shown that this operation results in greater tolerance to in-class variations while maintaining excellent discrimination abil ity. The introduction of nonlinearity was shown to provide greater rob ustness to the filter's response to noise and background clutter in th e input scene. We incorporate this new operation into the synthesis of a modified synthetic discriminant function filter. The filter is show n to produce sharp peaks, excellent discrimination without the need to include out-of-class objects, and good invariance to out-of-plane rot ation over a distortion range of up to 90 degrees. Additionally, the i ntroduction of nonlinearity is shown to provide greater robustness of the filter response to background clutter in the input scene. (C) 1998 Optical Society of America.