This is an Inkscape gradient implementation of the famous Python Matplotlib colormaps designed by Stéfan van der Walt and Nathaniel J. Smith:
> viridis
> inferno
> magma
> plasma
See: <https://bids.github.io/colormap/>
Those colormaps are perfectly perceptually uniform according to color distance in the CAM02-UCS color space. Here, an approximation of those colormaps is proposed by using only 17 gradient stops. Between the stops, the colors are linearly interpolated (by Inkscape or any browsers) in the sRGB color space (which is not ideal for uniform perception) as mentioned here:
<http://tavmjong.free.fr/SVG/COLOR_INTERPOLATION/>
The original data of the colormaps are available here (256 points):
<https://github.com/BIDS/colormap/blob/master/colormaps.py>
The font used for the text is Inconsolata. See <https://levien.com/type/myfonts/inconsolata.html>.
Fabien Fellay, 12.11.2018