This paper introduces two new edge detection algorithms. One uses multiple difference-based edge detectors. This scheme selects peak center by absolute maximum or center of mass techniques. The other algorithm is motivated by the observation that second-order enhancement improves human contour extraction, but generally confuses difference-based edge detectors. This algorithm translates intensity images into three state images (plus one, zero, and minus one), then uses multiple three-state edge masks to find edge positions. The second scheme has a multiple hardware implementation and interesting biological analogs. Finally, the two operators introduced are compared to some popular edge detection techniques from the literature.