title: RMagick remove white background from image and make it transparent
body: <p>I need to remove the white background from this image and make the background transparent. So it's just a black tick on the transparent background exported as a png.</p>
  
  <p>e.g. Turn</p>
  
  <p><img src="https://i.stack.imgur.com/WYAWe.jpg" alt="enter image description here"></p>
  
  <p>Into</p>
  
  <p><img src="https://i.stack.imgur.com/obv1J.png" alt="enter image description here"></p>
  
  <p>Any ideas?</p>