title: Removing Protrusion from A circle and Erode Radius
body: <p>Please anybody tell me how to remove only the protrusion from this image using just the morphological operations. Also I want to reduce the circle (white color) radius by 5 pixels. I know we can do that by using erosion but what should be the structuring element's(disk type) radius should be and how many iterations should we perform for the selected radius.</p>
  
  <p>I mean can we have structuring element se =strel('disk',5) and perform one iteration or se = strel('disk',1) and perform 5 iterations.</p>
  
  <p><img src="https://i.stack.imgur.com/O3Z7j.jpg" alt="enter image description here"></p>