The above is an interesting project to image the full Neptune system based on actual data returned by Voyager. According to the article published along with the image — Rolf Wahl Olsen composed this scene from actual images from the departing Voyager probe. The rings (which were never photographed in their entirety) are based on over-exposed images and then density mapped to a model which was applied to the scene. Even the stars are based on one of the over exposed images of the rings which revealed what the probe would have seen and that field data was inserted from and image generated by Google Sky.