title: Fisheye effect on IOS
body: <p>I'd like to create a Fisheye effect shown in many IOS Apps and some other interesting effects like color burn and so on ...
  Which is the best way to work on these features ? Could you suggest me some useful links or code ? </p>
  
  <p>I need understand in which direction i have to go to work on graphic effects that take an image as input and obtain a modified result of that as output. 
  Thank you. </p>