Okabe–Ito
Okabe & Ito (2002) — colorblind-safe qualitative set
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#e69f00 -
#56b4e9 -
#009e73 -
#f0e442 -
#0072b2 -
#d55e00 -
#cc79a7 -
#999999
On a map
A synthetic demo grid, classed with equal intervals — the point is the palette against real basemap ink, not the data. Switch themes to see how much basemap the palette leaves room for.
Metadata
Provenance
Masataka Okabe and Kei Ito published this set in 2002 as part of their Color Universal Design guidance for scientists, aimed at figures that stay readable for the roughly one in twenty people with color vision deficiency. The colors were chosen by working from how dichromats actually perceive hue, not by desaturating a normal-vision palette, and the accompanying guide explains the reasoning swatch by swatch. It has become the reference accessible qualitative palette across scientific publishing, and the authors ask only that use be acknowledged. One deviation to disclose: the canonical CUD set's eighth value is black (#000000), and this entry substitutes grey (#999999), the ninth member of the extended set, because pure black reads as a boundary or a label rather than a category fill on a map. That makes these eight colors a variant of the reference set rather than the reference set itself — the substitution is deliberate, it is shared with map-party's core catalog, and it is tracked for owner review.
When to use it
This is the palette to reach for when a small set of categories must be distinguishable by everyone — up to eight classes of anything nominal, from transit modes to habitat types. The swatches are strong and mid-to-high saturation, so give them a quiet basemap and let the categories carry the map. Beyond eight classes the set runs out; move to carto-safe or tol-muted rather than inventing extra colors, which will break the accessibility guarantee.
License
Free to use (uncopyrightable color values; attribution courtesy) · source
The color specification carries this license, which is separate from the MIT license on this site. See attribution.