private void GeneraTumbnail(string path, string img, short dimensione)
{
  System.Drawing.Image objImage = null;
  System.Drawing.Image objThumbnail = null;
  string strFilename;
  int shtWidth, shtHeight;
  strFilename = path + img;
  shtWidth = dimensione;
  try { objImage = System.Drawing.Image.FromFile(strFilename); }
  catch { /*errore...*/ }
  if (shtWidth == 0)
  {
    shtWidth = objImage.Width;
  }
  else if (Convert.ToInt32(Request.QueryString["width"]) < 1)
  {
    shtWidth = 100;
  }
  else
  {
    shtWidth = Convert.ToInt32(Request.QueryString["width"]);
  }
  shtHeight = objImage.Height / (objImage.Width / shtWidth);
  objThumbnail = objImage.GetThumbnailImage(shtWidth, shtHeight, null, System.IntPtr.Zero);
  Response.ContentType = "image/jpeg";
  objThumbnail.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
  objImage.Dispose();
  objThumbnail.Dispose();
}