Mathematical morphology is an efficacious theory and method

which used in image processing and pattern recognition

especially in image edge detection. This paper introduces the definition of soft morphology

then presents a robust edge detector based on it SMD (Soft Morphological Detector)

and compared with other edge detectors based on crisp morphology. The results of experiments show that this new detector SMD has very strong robustness

and performs better than other morphology detectors.