I've made a second notebook that uses the IPython interactive machinery to let anyone play with the parameters and explore different ways of setting them. you can download the notebook with that here: http://nbviewer.ipython.org/gist/mwaskom/842d1497b6892d081bfb (I made it using IPython 3.0rc1; I'm not certain if it will work on the 2.x series; sorry if that is the case). This stays with the general approach in the original notebook of using a linear ramp for chroma, which again maybe is not what we want. But it should let you get a better sense for the parameter space. As I said in the email to Olga, I think (a) I would advocate fairly strongly that matplotlib should design a custom colormap as its default, and (b) I think this approach (a cubehelix-like map in Hcl space) is a principled way of doing so (though maybe not optimal). But both of those points are independent of whether you end up going with the particular parameters that I used to generate the original proposal -- I have my own domain on which to impose my personal aesthetic preferences, and I don't need to take over matplotlib too :) (But I do think it's worth distinguishing the matplotlib default from the matlab default.) Michael