What is the difference between convhull and bwconvhull functions?

How can I use the function 'convhull' to get the output as shown in the figure?

I've used the function 'bwconvhull' for getting the output but it ended up as:

Answer 1

[Steven Lord]

You can't. Your hull isn't convex; a line drawn between the base of the wrist on the right side and the tip of the thumb would go outside your hull.

Perhaps you want to use alphaShape instead to get a shape that more closely follows the outline of the hands in your images? Note that alphaShape works on coordinates, not images, so you'd need to pass in the coordinates of the points in the hands as the input.