Optically computing the hit-miss transform for an automated cervical smear screening system

The hit-miss transform serves as a region-of-interest locator for cells from cervical smear images that show abnormal changes, which are indicative of malignancy, in their nuclei. An optical implementation of the hit-miss transform algorithm uses an analog spatial light modulator for gray-scale modulation at the filter plane of a 4f optical correlator. Gray-scale modulation at the filter plane improves correlator performance in comparison with a binary phase-only filter (BPOF) by reduction of the edge enhancement of kernels used in morphological detection of cancerous cervical cells. The hit-miss transform with a gray-scale amplitude and binary phase optical filter (GABPOF) for the hit filter and a BPOF for the miss filter shows a 47% reduction in total error versus the use of only BPOF filters to locate abnormal cells.