Figure 12: Analysis of a magnetic resonance image of a portion of the brain. On the left is a scatterplot of data value and gradient magnitude; no clear boundaries are evidenced. In the middle is an automatically generated opacity function of data value, and on the right is the rendered image. The goal of the visualization was to find the aneurysm; it is the large round shape visible in the lower half of the image.

Figure 13: Renderings of the feet in the female Visible Human dataset. Inset in each rendered image is the two-dimensional opacity function used to generate it. At the upper-left is the initial automatically generated opacity function and rendering. Editing out a small region of opacity at low data value and low gradient magnitude removed the surrounding material from the rendering (upper-right). Careful selection in the opacity function allows imaging of the registration cord (lower-left). Finally, the bones are visualized by selecting the right-most portion of the opacity function (lower-right).