Better if we never saw the picture at all?
Just saw this on TCM recently and found myself freaked out by the picture when we didn't know what it was starting to look like. That is until I saw the garish technicolor rendering that was supposed to be shocking. While definitely unpleasant I no longer found the picture horrifying. I felt like it was a bit of an anticlimax and shown much too soon. I'd much rather have had a lot longer without seeing the picture but the suspense building as something horrible is emerging in my imagination.
Or maybe even better would be never to see it at all. This to me is the greatest advantage the novel has over the movie. In never being able to physically see the picture, the novel's reader must paint for themselves its corrupted and ruined visage and that is something that each of us makes out of the stuff of his own worst nightmares. It doesn't get any scarier than that.