"Instant alpha" function in iPhone app
<p>Is there anything in the SDK which would allow you to replicate the instant alpha functionality found in some mac apps (Pages, Keynote, Preview) on the iPhone?</p>

<p>Basically my objective is to take a picture which contains a main object against a fairly even background, and eliminate the background leaving only the main object. The user could select the areas that represent the background. As an example, from this original: <a href="http://i.stack.imgur.com/vOgvn.jpg" rel="nofollow">http://i.stack.imgur.com/vOgvn.jpg</a></p>

<p>We would get this image after applying the effect (white background is transparent): <a href="http://i.stack.imgur.com/McGwA.png" rel="nofollow">http://i.stack.imgur.com/McGwA.png</a></p>
