var win=null;
function mostrarimagen(titulo, imagen, ancho, alto){
win=window.open('','','width=' + ancho + ',height=' + alto + ',scrollbars=no,resizable=0,toolbar=0');
win.document.write ('\n');
win.document.write (' \n');
win.document.write (' '+titulo+'\n');
win.document.write (' \n');
win.document.write (' \n');
win.document.write (' 
\n');
win.document.write (' \n');
win.document.write ('\n');
}