function img_roll(imgObject)
{
	changeOpac(imgObject, 50);
	return true;
}

function img_unroll(imgObject)
{
	changeOpac(imgObject, 100);
	return true;
}

function changeOpac(imageobject, opacity){
    if (navigator.appName.indexOf("Netscape")!=-1&&parseInt(navigator.appVersion)>=5)
    imageobject.style.MozOpacity=opacity/100;
    else if (navigator.appName.indexOf("Microsoft")!=-1&&parseInt(navigator.appVersion)>=4)
    imageobject.style.filters.alpha.opacity=opacity;
}