IE5.5+ has supported the CSS attribute “filter” where you convert a color image into grayscale using just CSS.
filter: progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);
Do other browsers support a similar CSS tag without using JavaScript?
You can check out: http://snipplr.com/view/2836/grayscale-img-with-css-crossbrowser/
I hope it helps. I would still recommend using server-side for image manipulation, or Photoshop.