function conectar(){
    if (window.XMLHttpRequest){
        return new XMLHttpRequest()
    }else if (window.ActiveXObject){
        return new ActiveXObject("Microsoft.XMLHTTP")
    }
    return false;
}
function buscar_datos(imagen){
    xmlhttp = conectar();
    xmlhttp.open("POST", "cimagen.php", true);
    xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    xmlhttp.onreadystatechange=function() {
        if (xmlhttp.readyState==1) {
            document.getElementById('mostrando').innerHTML = '<table width="100%" height="200" border="0" cellpadding="0" cellspacing="0"><tr><td valign="middle"><div align="center"><img src="imagenes/cargando.gif" border="0"></div></td></tr></table>';
        }
        if (xmlhttp.readyState==4) {
            document.getElementById('mostrando').innerHTML = xmlhttp.responseText;
        }
    }
    xmlhttp.send("imagen=" + imagen);

}