See the Pen <a href="https://codepen.io/firegroove/pen/yLZQZPP/40e474c627fbaa6455526ece63c49eef"> d3 scale interpolation Rainbow (Cubehelix) perceptually uniform gradients</a> by Firegroove (<a href="https://codepen.io/firegroove">@firegroove</a>) on <a href="https://codepen.io">CodePen</a>.
