title: How to find K random different pixels in an image?
body: <p>I know how to find a random pixel by using rand function, for both x&amp;y in the limits of the image. Then do it K times with a loop.</p>
  
  <p>However I'd like to do it in smarter way and make sure I don't pick the same 
  (x, y) coordinate. Thanks in advance!</p>