How did they do the effect in the page at http://labs.saurabh-sharma.com/themes/cruz/wp/
<p>How did they do the effect in the page at <a href="http://labs.saurabh-sharma.com/themes/cruz/wp/" rel="nofollow">http://labs.saurabh-sharma.com/themes/cruz/wp/</a> </p>

<p>I am thinking they put a 0% opacity new image above the existing image and slowly increase the opacity to 100% without changing the opacity of the existing image. (so after 100 "ticks" the new image will cover the old image)</p>

<p>Or is it that the opacity of the new image goes from 0 to 100% WHILE the opacity of the old image goes from 100% to 0 simulataneously?</p>

<p>Or is it something else altogether?</p>

<p>Well the effect looks very good, so I'm trying to build something like it and was wondering how did they do it.</p>
