These below are two copies of a seismic horizon from the open source Penobscot 3D seismic survey coloured using two different colormaps (data from Hall, 2014).
Do you think either of them is ‘better’? If yes, can you explain why? If you are unsure and you want to learn how to answer such questions using perceptual principles and open source Python code, you can read my tutorial Evaluate and compare colormaps (Niccoli, 2014), one of the awesome Geophysical Tutorials from The Leading Edge. In the process you will learn many things, including how to calculate an RGB colormap’s intensity using a simple formula:
import numpy as np ntnst = 0.2989 * rgb[:,0] + 0.5870 * rgb[:,1] + 0.1140 * rgb[:,2] # get the intensity intensity = np.rint(ntnst) # rounds up to nearest integer
…and how to display the colormap as a colorbar with an overlay plot of the intensity as in Figure 2.
Hall, M. (2014) Smoothing surfaces and attributes. The Leading Edge 33, no. 2, 128–129. Open access at: https://github.com/seg/tutorials#february-2014
Niccoli, M. (2014) Evaluate and compare colormaps. The Leading Edge 33, no. 8., 910–912. Open access at: https://github.com/seg/tutorials#august-2014