Lightness and perceptual derivatives of colourmaps

[Fonotec]

Nice that a new set of discrete colourmaps were created here. The main point that is currently unclear is how perceptually uniform the corresponding colourmaps are? This is both relevant in terms of the perceptual derivative and the perceptual lightness derivative or the lightness curve. This will be good to add to the repository, such that the sensitivity of the colourmap is clear. Currently, this is unclear.

For example the maker of the twilight colourmap did this in his repository: https://github.com/bastibe/twilight