title: Clear image with fade border
body: <p>I have two <code>UIImageView</code> with same frame. One <code>imageView</code> above second <code>imageView</code> now I'm erasing upper <code>imageView</code> using <a href="http://developer.apple.com/library/ios/#documentation/coregraphics/reference/coregraphics_framework/_index.html" rel="nofollow noreferrer">Core Graphics</a>. My problem is that the border of eraser is very sharp I want faded border i.e. after erasing the upper image should match the lower one's pallet. See below example -  <br>
  <img src="https://i.stack.imgur.com/kdPaq.png" alt="enter image description here"><img src="https://i.stack.imgur.com/25xD0.jpg" alt="enter image description here">
  <br>
  I used these two images and below is result - <br>
  <img src="https://i.stack.imgur.com/Xy7dR.png" alt="enter image description here"> <br><br>
  As you can see in this image eraser's border is very sharp. I want to make it faded out like in the middle it should be dark then light then more light and so on i.e. we cant see the width and end of brush. And here is my - <a href="http://dl.dropbox.com/u/74641080/FaceSwitching.zip" rel="nofollow noreferrer">My Sample Code</a> <br> Let me know if my question is not clear enough. <br></p>