Presently gradients used in color scale conditional formatting are rgb gradients and it would be useful to also have the ability to use HSV and HSV inverse gradients.
With HSV gradients we could have gradients like rainbow (3300FF to FF9900) and with HSV inverse gradients we could have gradients like topo (4C00FF to FFE0B3). Both of these gradients are color palettes found in R ( http://zoonek2.free.fr/UNIX/48_R/g327.png ).
You can see the difference between rgb and non-rgb gradients with this tool
Setting NEW as ux-advise enhancement.