lá, preciso obter a altura e a largura rapidamente de uma imagem carregad

sta é a função PHP que estou usando, mas não retorna nada para a largura e a altur

Podes ajudar-me, por favor

list($width, $height, $type, $attr) = getimagesize($_FILES["Artwork"]);
$min_width = "1000";
$min_height = "1000";
if ((($_FILES["Artwork"]["type"] == "image/gif") || ($_FILES["Artwork"]["type"] == "image/jpeg") || ($_FILES["Artwork"]["type"] == "image/jpg")
|| ($_FILES["Artwork"]["type"] == "image/pjpeg")) && ($_FILES["Artwork"]["size"] < 20000000) && ($width > $min_width) && ($height > $min_height) && ($width == $height))
  {


  if ($_FILES["Artwork"]["error"] > 0)
    {
    //echo "Return Code: " . $_FILES["Artwork"]["error"] . "<br />";


   }else{
      move_uploaded_file($_FILES["Artwork"]["tmp_name"],
      $path_image . $imageName);
      header("Location: http://pitchmystuff.co.uk/m/digidist/tracks/".$idAlbum."");
      }



   }else{
    //echo "invalid file";

    echo '<script>
    alert("There was an error uploading your coverart file. Please check the requirements and try again.'.$width.$height.'");
    document.location ="http://pitchmystuff.co.uk/m/digidist/albums/";
    </script>';


    }