The series looks good to me. Of course, we can already read 8-bit tiffs just fine, but I guess your app makes use of the 8bpp RGB format.
We could probably avoid a double conversion between rgb and bgr when reading an 8-bit tiff as rgb, by implementing and using the IWICBitmapSourceTransform interface, but MSDN seems to claim that the native TIFF decoder doesn't do this.