This article presents a edge detection method

which is based on the dual-threshold nonlinear derivative operator.Firstly

gray image is used to calculate the right and left derivative.Secondly

dual-threshold is used to injust the right and left derivative to remain the meaning edge information.At last

the two derivatives are merged to get the image gradient.can control the ability of reducing noise;can ensure detection of the one pixel width edge lines;and the nonlinear derivative scheme can solve the problem of delocalization.By comparing and analying it with the traditional discrete gradient operators in the experimental demonstrations

we find that this operator is not only with advantages of sinplicity

higer accuracy of detection

but also get better edge image and higer SNR in the case of no any smootning.