function initImageBackground(_options) {
		var options = $extend({
			rel: 'imageback'
		}, _options || {});
		
		var elements = $$(document.links).filter(function(el) {
			if ((el.rel) && (el.rel.indexOf(options.rel) != -1)) 
				return true;
			else
				return false;
		});
		for (var i = 0; i < elements.length; i++) {
			var el = elements[i];
			el.addEvent("click", function() {
				Cookie.write( 'background', this.href, {duration: 1} );
				this.blur();
				var sEl = this;
				var imgCap = "";
				if (this.getElements("img").length > 0)
					sEl = this.getElements("img")[0];
				if ((sEl.alt) && (sEl.alt != ""))
					imgCap = sEl.alt;
				else if (sEl.title)
					imgCap = sEl.title;
				else if (sEl.parentNode.title)
					imgCap = sEl.parentNode.title;
				var _options = $extend({
					image: this.href,
					caption: imgCap,
					startElement: sEl
				}, options || {});
				_options.image = this.href;
				_options.caption = imgCap;
				Imageback(_options);				
				return false;
			});
		}
	}

	var Imageback = function(_options){
		var m = $('bg');
		var fx = new Fx.Tween(m,{
			duration: 3000,
			onComplete: function(){ 
					
					m.src=_options.image;
					m.fade('in');
			}
		});
		fx.start('opacity',1,0);
		$('contenuto').set('opacity',0);
	};