# Smooth rainbow

Canonical URL: https://colorcurio.us/colormaps/tol.smooth-rainbow
Source type: Colormap
Type: sequential
Collection: tol
Attribution: Paul Tol — SRON Technical Note (2018)
License: BSD-3
Source: https://personal.sron.nl/~pault/data/tol_colors.py
Tags: rainbow, perceptually-uniform
Stops: 256

## Summary

Smooth rainbow is a sequential colormap from the tol collection. Inspect its perceptual lightness, chroma, and hue profile on colorcurio.us.

SRON 2018 perceptual smooth rainbow.

## Perceptual profile (OKLCh)

- Lightness: 0.560 → 0.660 (range 0.177, min 0.544, max 0.721); non-monotonic; midpoint 0.720
- Chroma: min 0.147, max 0.229, mean 0.185
- Hue: 352.5° → 35.4° (span 60.7°), path monotonic-cw; quadrants: rose, red, orange
- Endpoint temperature: warm → warm
- Perceptual ΔE: total 65.2, mean/step 0.256, max step 0.532, smoothness 0.489, speed 0.256

## Colorblind safety (ΔE under simulated CVD)

- Protanopia: ΔE total 65.0; preserves order: no
- Deuteranopia: ΔE total 57.6; preserves order: no
- Tritanopia: ΔE total 36.5; preserves order: no

## Related

- Family: https://colorcurio.us/colormaps/families/tol
- All colormaps: https://colorcurio.us/colormaps