function foto(url,largura,altura) {

	posEsq     = (window.screen.width-largura)/2;
	posDir     = (window.screen.height-altura)/2;
	nome       = 'fotosGp';
	parametros = "toolbar=0,scrollbars=0,location=0,status=0,menubar=0,resizable=0,width="+largura+",height="+altura+",left="+posEsq+",top="+posDir+"'";

	window.open(url, nome, parametros);
	}