cvdsafe

Is your palette colorblind-safe? One import to check and fix color palettes for color-vision deficiency — protanopia, deuteranopia, tritanopia.

npm install cvdsafe

const hue = require("cvdsafe");

hue.isSafe(["#d7191c", "#1a9641"]);            // false — red and green collapse under deutan/protan
hue.isSafe(["#0072b2", "#e69f00", "#009e73"]); // true  — an Okabe-Ito set stays distinct

hue.checkPalette(["#d7191c", "#1a9641"]);
// { pass: false, types: { deutan: { conflicts: [{ a:"#d7191c", b:"#1a9641", normal:70.6, sim:8.1, ... }] } } }

hue.fixPalette(["#d7191c", "#1a9641"]).colors;  // a safe palette, kept as near the originals as possible
hue.simulate("#d7191c", "deutan");              // how that red looks to a deuteranope

What it does

• isSafe(colors) → true/false for the whole palette.
• checkPalette(colors) → every pair that stays distinct to normal vision but collapses under a deficiency, with the CIEDE2000 difference before and after simulation.
• fixPalette(colors) → an adjusted palette that passes, separated along lightness (the axis color-vision deficiency preserves), staying near the originals.
• simulate(color, type) → the color as a given deficiency sees it.
• checkContrast(fg, bg) → WCAG contrast ratio and AA/AAA pass — the legibility axis.

How it decides

cvdsafe is a front door to the opticquiz-cvd engine, which simulates deficiency with the Machado, Oliveira & Fernandes (2009) matrices and measures color difference with CIEDE2000. The method is published open access: https://doi.org/10.5281/zenodo.21310578

Every function here is opticquiz-cvd's, unchanged — this package adds the name and one convenience, so there is never a second copy of the colorimetry to drift.

Not a legal audit

A screening aid for the color-distinguishability axis of accessibility. It does not replace a WCAG/ADA audit, and no screen-based check is a clinical diagnosis.

Licence

MIT.