The new release of Image_3D (0.4-alpha) is out. It was quite some time ago, Richard Davey wrote his great introduction into Image_3D. He asked for some different types of lights, I didn't thought of, when I released Image_3D first. This needed a minor change in the API you use to create lights, but offers some great improvements. See changelog for details.
Some of the other additions mentioned include, as mentioned, the ability to create different types of lights (light, ambient, point, and spotlight) and the inclusion of an object that allows for the creation of bezier areas from an array of points.