save image to tiff format

Question

hi all, i am using this code to save file in tiff format

            Image img = Image.FromFile(Page.MapPath(urlPath) + FileName + "_.TIF"); 
            MemoryStream imageStream = new MemoryStream(); 
            //img.Save(imageStream, ImageFormat.Bmp); 
            img.Save(imageStream, ImageFormat.Tiff); 
            byte[] contentBuffer = new byte[imageStream.Length]; 
            imageStream.Position = 0;//Reset the position at the start
            imageStream.Read(contentBuffer, 0, contentBuffer.Length); 
            Image newImage = Image.FromStream(imageStream);
            newImage.Save(Page.MapPath(urlPath) + FileName + ".TIF");

while doing this // img.Save(imageStream, ImageFormat.Tiff); it raise exception any suggestions ?