function mostrarImagen(imagen,titulo,width,height){
var win=null;
var sbars = '';
var img = new Image();
var w = width;
var h = height;
img.src = imagen;
sbars = 'scrollbars=no';
if (width > (screen.width - 50))
{
sbars = 'scrollbars=yes';
width = screen.width - 50;
height += 20;
}
if (height > (screen.height - 50))
{
sbars = 'scrollbars=yes';
height = screen.height - 50;
width += 20;
}
win=window.open('','','width='+width+',height='+height+',top=0,left=0,resizable=1,toolbar=0,'+sbars);
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');
}