How can I highlight an image on an iPhone?
<p>I have a photo displayed on an iPhone. I would like to lower brightness of the photo at first, and when the user touches the photo, I would like to raise the brightness of the rectangular region near where the user touched, like this:</p>

<p><a href="http://www.cottagearts.net/tut%5Fimages/tut%5Fcropping%5Fpse%5F06.jpg" rel="nofollow">www.cottagearts.net/tut_images/tut_cropping_pse_06.jpg</a></p>

<p>Could anyone point me to a simple way of doing this?</p>
