Because the representation of the spatial data is related with scale characteristics

element feature extraction is meaningful only when it is under certain scale rcpectively. Different sizes of structure element are suitable for image features on different spatial scales. It cannot obtain the optimal effects can not be obtained if the size of structure element. Therefore

the design of size of structure element plays an important role on extracting image information. Based on the analysis between the mathematical morphology characteristic and the size of structure element

the optimal quantitivc relationship is acquired

between the size of structure element

the size of feature factor and special scale of feature factor denotes size of structure element is unsuitable

A denotes size of feature factor and denotes spatial scale of feature factor. Then the adaptive algorithm for ascertaining the optimal size of structure element is designed by calculating and comparing the difference information between the neighborhood spatio-scale gradient images. And show experimental results the correctness and effectiveness of the algorithm. In the end

the difference between the extraction result by the classical edge operators and the operator presented in the paper are listed and analyzed

then the conclusion that the operator is superior to other edge operators on robust

position and contrast is reached.