if (this.IsInitialized)
{
    MemoryStream ms = new MemoryStream();
    LocalizationInfoRes.CountryFlag.Save(ms, ImageFormat.Jpeg);
    ms.Position = 0;
    this.imgFlag.BeginInit();
    this.imgFlag.Source = BitmapFrame.Create(ms);
    this.imgFlag.EndInit();
    ms.Close();
}