title: Bitmap compare method on the iPhone (unity3d)
body: <p>What would be the best method to compare 2 bitmaps and get the correlation between the 2 (0 being completely different and 1 being exactly the same) in Unity3d on the iPhone? I am using C# since documentation says that using Boo or UnityScript will increase the size of the application.</p>
  
  <p>What I need is something similar to the fingerprint identification methods but not as accurate. Since this is intended to run on the iPhone performance is a big issue here.</p>
  
  <p>Example images: </p>
  
  <p><a href="http://img25.imageshack.us/img25/303/294906.jpg" rel="nofollow noreferrer">alt text http://img25.imageshack.us/img25/303/294906.jpg</a>
  <a href="http://img138.imageshack.us/img138/842/40248741fireworkexplosi.jpg" rel="nofollow noreferrer">alt text http://img138.imageshack.us/img138/842/40248741fireworkexplosi.jpg</a></p>
  
  <p>For those I would expect to have a correlation factor of about 0.5 since they are similar but differ in color. There are a number of different dimensions of comparison, but the basic ones are color and shape.</p>
  
  <p>Any help will be greatly appreciated.</p>