c# image to byte array

public byte[] ImageToByteArray(System.Drawing.Image imageIn)
{
   using (var ms = new MemoryStream())
   {
      imageIn.Save(ms,imageIn.RawFormat);
      return  ms.ToArray();
   }
}

foreach (var file in files)
{
  if (file.Length > 0)
  {
    using (var ms = new MemoryStream())
    {
      file.CopyTo(ms);
      var fileBytes = ms.ToArray();
      string s = Convert.ToBase64String(fileBytes);
      // act on the Base64 data
    }
  }
}