title: Remove white backgrounds from images
body: <p>I have some product photos, from which I would like to remove the white background.
  An example:</p>
  
  <p><a href="https://i.stack.imgur.com/bZkXv.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bZkXv.jpg" alt="alt text"></a><br>
  <sub>(source: <a href="http://www.dewalt.at/ProductImages/imports/EU_Images/Dewalt/573786_DC415N.jpg" rel="nofollow noreferrer">dewalt.at</a>)</sub>  </p>
  
  <p>Is there a nice library or a manual way to do it with Cocoa or C?
  For which keywords (image processing methods) do I have to search?</p>