var filtro=false;
function filter(){
	mi_imagen1=new Image
	mi_imagen1.src="../images/luzao.png"
	mi_imagen2=new Image
	mi_imagen2.src="../images/luza.png"
	if(!filtro){
		document.getElementById("filtro2").style.visibility='visible';
		filtro=true;
		document.images['prueba'].src=mi_imagen2.src
	} else {
		document.getElementById("filtro2").style.visibility='hidden';
		filtro=false;
		document.images['prueba'].src=mi_imagen1.src;
	}
}