Efect de tranzitie a unei imagini

Codul este unul simplu, dar cu un efect foarte frumos
Demo: [You must be registered and logged in to see this link.]

Code:

.clasa {
background: url(http://i44.servimg.com/u/f44/16/84/52/28/abstra10.jpg);background-position: 80% 0%;-moz-transition-duration: 1s;
-webkit-transition-duration: 1s;
-o-transition-duration: 1s;
height: 180px;}

clasa:hover {
background: url(http://i44.servimg.com/u/f44/16/84/52/28/abstra10.jpg);background-position: 80% 100%;
-moz-transition-duration: 1s;
-webkit-transition-duration: 1s;
-o-transition-duration: 1s;}