The "S2 file" mentioned on the liked page gives a look-up table for the cividis scale: http://journals.plos.org/plosone/article/file?type=supplementary&id=info:

The "S2 file" mentioned on the liked page gives a look-up table for the cividis scale: http://journals.plos.org/plosone/article/file?type=supplementary&id=info:doi/10.1371/journal.pone.0199239.s002 http://journals.plos.org/plosone/article/file?type=supplemen... Apart from the comment on line 1, that file contains 256 lines with a colour. I suppose to get a finer scale, you can interpolate with any reasonable function you like since the differences are so small.