opticquiz-cvd

Check color palettes for colorblind-safety — zero dependencies, runs anywhere JS runs.

Simulates protanopia, deuteranopia and tritanopia (Machado et al. 2009 model, in linear RGB), scores perceptual difference with CIEDE2000, and flags the pairs that are clearly distinct to normal vision but collapse under a color-vision deficiency simulation.

The method traces to the open-access OpticQuiz paper — https://doi.org/10.5281/zenodo.21310578 — and powers the checker at https://opticquiz.com/checker/.

Install

npm install opticquiz-cvd

Use

const cvd = require("opticquiz-cvd");

// Check a palette
const report = cvd.checkPalette(["#d7191c", "#1a9641", "#2166ac"]);
report.pass;                 // false — a pair collapses under simulation
report.types.deutan.conflicts;
// [{ a:"#d7191c", b:"#1a9641", normal:70.6, sim:8.1, severity:"risk" }]

// Simulate one color
cvd.simulate("#d7191c", "deutan");   // "#8a7b0c"

// Perceptual difference (CIEDE2000)
cvd.deltaE("#d7191c", "#1a9641");    // 70.6

checkPalette(hexes, opts?)

Returns { pass, types: { protan, deutan, tritan } }. Each type has conflicts[] ({ a, b, normal, sim, severity }) and pass. Options: distinct (a pair must be at least this different to normal vision to count; default 13) and collapse (a simulated difference below this is a conflict; default 10; severity:"severe" below 5).

Honest scope

This simulates a model of color-vision deficiency — an approximation of a diverse population — not any single person's vision, and results depend on an uncalibrated screen. It reliably catches classic red-green and blue-yellow conflicts. It is not a legal accessibility audit and does not certify ADA, Section 508, WCAG, or EU Accessibility Act compliance, which cover far more than color.

License

MIT. Method: Machado, Oliveira & Fernandes (2009) + CIEDE2000.