void cam_Initialized(object sender, CameraOperationCompletedEventArgs e)
        {
            int width  = Convert.ToInt32(_photoCamera.PreviewResolution.Width);
            int height = Convert.ToInt32(_photoCamera.PreviewResolution.Height);

            _luminance = new PhotoCameraLuminanceSource(width, height);

            Dispatcher.BeginInvoke(() =>
            {
                _previewTransform.Rotation = _photoCamera.Orientation;
                _timer.Start();
            });
            _photoCamera.FlashMode = FlashMode.Auto;
            _photoCamera.Focus();
        }
        void cam_Initialized(object sender, CameraOperationCompletedEventArgs e)
        {
            int width = Convert.ToInt32(_photoCamera.PreviewResolution.Width);
            int height = Convert.ToInt32(_photoCamera.PreviewResolution.Height);
            _luminance = new PhotoCameraLuminanceSource(width, height);

            Dispatcher.BeginInvoke(() =>
            {
                _previewTransform.Rotation = _photoCamera.Orientation;
                _timer.Start();
            });
            _photoCamera.FlashMode = FlashMode.Auto;
            _photoCamera.Focus();
        }