title: jCaptcha - Refresh only image not whole page
body: <p>I'm using jCaptcha (http://jcaptcha.sourceforge.net/) on our website.  The problem is sometimes it's very difficult to read the image. So, we are planning to provide a button named 'REFRESH' next to the jcaptcha image and upon clicking REFRESH button, it has to refresh only the jcaptcha image not the entire page/portlet. How can we do that?</p>