Modified filter synthetic discriminant functions for improved optical correlator performance

This paper considers the filter-encoding constraints applied to construction of the synthetic discriminant function (SDF), with a view of synthesizing the SDF such that it is contains mostly higher frequency components of the individual training-set image, by using a linear combination of a set of preprocessed training images i.e filter modulated. This filter-encoding constraint id applied to the SDF and termed modified filter SDF or MfSDF. Comparison of the performance of the MfSDF filter with that of the fSDF filter using modulators set to be binary phase-only filter (BPOF) and a phase-only filter (POF) shows the BPOF/MfSDF is not subject to distortions for in-plane object rotation upto 65°, whereas the BPOF/fSDF achieves only 45°. The MfSDF also provides better discrimination and signal-to-noise ratio. Applications to real-time optical correlation using commercially available modulators is discussed.