Project 2: Color Mapping

Ryan Miller - millerrv@purdue.edu

Task 1 - MRI Data (MRI.py)

I chose this color map to highlight some anatomical structures of the brain. At one extreme of the color map, shades of blue highlight the cerebrum, with darker blue representing gray matter and lighter blue showing white matter. The skull, probably due to its density, also shows up as a ring of blue surrounding the head. The dural sinus, a cleft between the hemispheres of the brain, is also present in the center of the slice in blue.

At the other extreme of the color map, the dura matter, arachnoid matter, and pia matter are shown in yellow and orange. The subarachnoid space, the fluid-filled space that surrounds the cerebrum, is left black.

This color map is a modified version of the "Rainbow" color map discussed in class. I modified it so that YELLOW would appear adjacent to BLUE, as this represents one of the axes hard-wired into our visual system. The nearby colors of RED and DARK BLUE vary the intensity or value to represent related anatomical structures.

One potential weakness to this approach is that, when viewed in a continuous color map, related structures are sometimes difficult to separate, for instance the white and gray matter of the cerebrum. Under a discrete color map, however, the separation becomes quite clear.

Overall, the discrete color map seems to better highlight anatomical structures of the brain due to the clear separation of hue/saturation/value of colors.

One last note: I left a range (0-8124) in both color maps black to hide the background of the image, which does not contain any anatomical structures.



Task 2 - Bathymetry Data (Altitude.py)

For this task, I selected four color maps, all discussed in class:

  1. Heated
  2. Blue-Yellow
  3. Optimal
  4. Rainbow
Each of the color maps seems to highlight something different in the altitude data, justifying the use of multiple color maps. For instance, the heat map seems to best show the depth of the ridges of mountains near the center, while the optimal color map shows the ridges along the coast. The rainbow color maps makes differences in altitude most apparent, because they appear in completely different colors, such as green and pink. The blue-yellow map perhaps best shows the number of mountains, because they appear as yellow against a blue-ish gray background.

There are also some weaknesses to each of the color maps. The heat map does not readily show the comparative size of mountains because it is more difficult to distinguish between the varying intensity. Similarly, the optimal map "washes out" most of the lower mountains with visually-similar shades of green. The blue-yellow map appears to lack the depth of the other maps, and the rainbow map fails to clearly show mountain ridges along the coast.

When compared to their discrete counterparts, the continuous maps offer a superior view of the mountain ranges. The discrete maps just don't seem to capture the depth that the continuous color maps provide. On the other hand, they do make the task of finding the highest mountain areas quite easy.