The colormap demos shown:

http://matplotlib.org/examples/color/colormaps_reference.html

and

http://matplotlib.org/users/colormaps.html

do not include all colormaps that are available in Matplotlib. They also are not consistent with each other in that they show different subsets of the Matplotlib colormaps (e.g. #2659 treated binary and gray as equivalent but #3301 did not. For the record, they are not equivalent.). I can tackle this issue soonish---I just wanted to create an issue as a reminder. I also think it would be helpful if these categorizations were part of Matplotlib and available programmatically. Also related: #889.