I am trying to extract the outer edge of the attached image. Could you please advice me how to do it?
One method to isolate the outer edge in Mathematica is to use the
Note: I hand tuned the program for this image (it will not work for other images).
img = Import["https://i.stack.imgur.com/0wc6Q.jpg"]; EdgeDetect[img, 1, .43] - EdgeDetect[img, 1, .45]
An approach that doesn't need too much tweaking is to use LocalAdaptiveBinarize followed by the selection of the largest component:
img = Import["https://i.stack.imgur.com/0wc6Q.jpg"]; object = ColorNegate@DeleteSmallComponents[LocalAdaptiveBinarize[img, 30]] MorphologicalPerimeter@SelectComponents[object, "Count", -1]