opencv2_The research of Sobel operation by KUAN YU CHOU

If you want to find and obtain the result of  horizontal edges  , you need to use the vertical derivative(The derivative of Y ) 

If you want to find and obtain the result of vertical edges  , you need to use the horizontal derivative(The derivative of X )


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At first , I try to capture the result of horizontal edges (the derivative of Y )

In this case  , you can see the morphology of Closed-operation ( dilate first, and then  erode )

dilate  is a word related to  "expand"  and   "swell"  

erode is a word related to "minify" and "narrow"

the Closed-opertion will help us to delete the white space between each of horizontal edges and connect the area which is filled with much edges.