function obre_bigi(img,descripcio,colors)
{

     var w=655;
     var h=478;
    if(screen.width)
    {
    var winl = (screen.width-w)/2;
    var wint = (screen.height-h)/2;
    }
    else
    {
    winl=0;
    wint=0;
    }

    if (winl < 0) winl = 0;
    if (wint < 0) wint = 0;

    var settings = 'height=' + h + ',';
    settings += 'width=' + w + ',';
    settings += 'top=' + wint + ',';
    settings += 'left=' + winl + ',';
    settings += ",status=no,toolbar=no,titlebar=no,menubar=no,location=no";

    var mostra_gran=window.open("/appl/botiga/mostra_gran.php?img="+img+"&descripcio="+escape(descripcio)+"&colors="+escape(colors),"mostra_gran",settings);
    mostra_gran.focus();

}