We use circular versions of advanced distortion-invariant filters such as optimal trade-off synthetic discriminant function and distance classifier correlation filters to obtain rotation invariance with an optical correlator. The filter noise performance is compared using a common measure of probability of error because the filters have different characteristics. The filters are real-valued so they can be implemented on a variety of SLMs. The circular symmetry of the filters significantly decreases their computational requirement.
Kozaitis, Samuel Peter and Thangwaritorn, Sila, "Circular optimal trade-off and distance-classifier correlation filters" (2000). Electrical Engineering and Computer Science Faculty Publications. 70.