window.onload = resizeimg;
        function resizeimg()
        {
           if (document.getElementsByTagName)
           {
              for (i=0; i<document.getElementsByTagName('img').length; i++)
              {
                 im = document.getElementsByTagName('img')[i];
                 if (im.width > 725 && im.src != "http://farm4.static.flickr.com/3563/3483658297_873a9c744f_o.jpg")
                 {
                    im.style.width = '500px';
                    eval("pop" + String(i) + " = new Function(\"pop = window.open('" + im.src + " ','fullscale','width=400,height=400,scrollbars=1,resizable=1'); pop.focus();\")");
                    eval("im.onclick = pop" + String(i) + ";");
                    if (document.all) im.style.cursor = 'hand';
                    if (!document.all) im.style.cursor = 'pointer';
                    im.title = 'Pulsa aquí para ver la imagen en su tamaño original ';
                 }
              }
           }
        }