Hello all,

I want to find the external edge of an object.

I used Canny, but it finds me any edge (inside edges as well)

When I play with the thresholds somtimes it pass skip the external edge but finds an internal one.

Solution anyone?


Perhaps using a Sobel operator and using the gradient direction would help. "Internal" and "external" have little meaning to a map of pixel intensities. Those are rational designations of your own making that you have to quantify and qualify if you want your program to make any distinction between them.