cmap alteration

[stefraynaud]

I plan to use your colormaps as much as possible. However, it is for instance hard to draw lines onto filled objects since the colormaps goes generally from very dark to very white, or the reverse: black lines or white lines or texts are not that visible around extremess.

How about the possibility to alterate a colormap when calling the cmap() function, keeping them perceptually uniform.
Here is probably an example of alteration that allow to plot dark lines that are always visible:
http://www.ifremer.fr/vacumm/tests/test_color_whiten.html

[kthyng]

I have finally addressed this with commit 00ac131, which is now integrated. It is in the function cmocean.tools.lighten.

Note that depending on what you are plotting with, you could alternatively input an alpha value to lighten your plot, but this function allows you to change the alpha value of the colormap itself to make it transparent.