function show_cover(img,width,height,adm){
    var a;
    var b;
    var url;
    vidWindowWidth=width;
    vidWindowHeight=height;
    a=(screen.height-vidWindowHeight)/5;
    b=(screen.width-vidWindowWidth)/2;
    features = "top=" + a + ",left=" + b + ",width=" +
                vidWindowWidth + ",height=" +
                vidWindowHeight +
                ",toolbar=no,menubar=no,location=no,directories=no,scrollbars=yes,resizable=no";

    url="utils/show_cover.php?img=" + "../" + img;
    window.open(url,'',features,true);
  }