title: How to animate image over other image in Css or Javascript?
body: <p>Lets say First image is black &amp; white.
  Second image is colored.
  After some timeout B/W image should  change to colored image..with animation
  just like loading progress bars? how can I do this using Css or JavaScript ?</p>
  
  <p><strong>[Added for clarity from a comment by the OP, below]</strong></p>
  
  <blockquote>
    <p>OP: is it possible with some slow linear kind of animation ?? like filling
    water in glass..color filling in b/w image ?</p>
  </blockquote>