function xmlhttp(){
	var xmlhttp;
	try{xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");}
	catch(e){
		try{xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");}
		catch(e){
			try{xmlhttp = new XMLHttpRequest();}
			catch(e){
				xmlhttp = false;
			}
		}
	}
	if (!xmlhttp) 
			return null;
		else
			return xmlhttp;
}

function cambiar_foto(foto,rutaweb,ancho,alto) {

	var ajax = xmlhttp();
	var alto = parseInt(alto);
	var foto_g = document.getElementById("foto_g");

	ajax.onreadystatechange=function(){
		if(ajax.readyState==1) {
			foto_g.style.height = alto+10;
			foto_g.innerHTML = '<img src="'+rutaweb+'img/cargando.gif" style="border:0px; padding:0px; margin:0px;">&nbsp;Loading...';
		}
		if(ajax.readyState==4) {
			foto_g.innerHTML = '<img src="'+foto+'" width="'+ancho+'" height="'+alto+'">';
		}
	}

	ajax.open("GET", rutaweb+"index.php",true);
	ajax.send(null);

	return false;

}