An experimental study was conducted to determine the effects of nonoptimum noise conditions upon the SNR of optical spatial filters. The experiments were performed utilizing matched and inverse filters that are generally recognized as the best types of filters for pattern recognition. Their signal-to-noise ratios were compared as a function of varying background noise. The results indicate that (1) the SNR is a decreasing function of increasing background noise size, and (2) the performance difference between the inverse and matched filters increases as the noise size decreases.
J. E. Wasielewski, "Optical Filter Analysis as a Function of Nonoptimum Noise Conditions," Appl. Opt. 10, 2439-2441 (1971)