function rollover_init() {
        
	if (document.getElementById)
		var x = document.getElementById('portfolios').getElementsByTagName('IMG');
	else if (document.all)
		var x = document.all['portfolios'].all.tags('IMG');
	else return;

    var preloads = new Object();
    for (var i=0;i<x.length;i++)
    {
        original_src = x[i].src;
        components = original_src.split('/');
        uri="";
        for (var j=0; j < components.length -1 ; j++) {
          uri += (components[j] + "/");
        }
        /* alert(uri);
         */
    	preloads['n'+x[i].id] = new Image;
        preloads['n'+x[i].id].src = uri + x[i].id + '.jpg';
        preloads['o'+x[i].id] = new Image;
        preloads['o'+x[i].id].src = uri + x[i].id + '-a.jpg';
        preloads['o'+x[i].id].onerror = function () {this.src=uri + '/error.jpg'}
		x[i].onmouseover = function () {this.src=preloads['o'+this.id].src;}
        x[i].onmouseout = function () {this.src=preloads['n'+this.id].src;}
	}
}