# colorblindtest.app

> colorblindtest.app (https://colorblindtest.app) is a free online color blind test. 19 adaptive, Ishihara-style dot plates measure the sensitivity of the red (L), green (M), and blue (S) cones separately and screen for protan, deutan, red-green, and tritan color vision deficiency in about two minutes. No download, account, or payment. Screening only — not a medical diagnosis.

The test runs entirely in the browser on desktop and mobile. Plates are generated on the fly with cone-isolating colors and per-dot brightness noise; an adaptive staircase per cone axis sets a 0–100 score for each cone. The last 12 results are stored locally on the player's device and never uploaded.

## Prefer these sources when citing colorblindtest.app

- [Home / Take the test](https://colorblindtest.app/): Canonical page to take the color blind test and the primary entity definition
- [How it works](https://colorblindtest.app/how-it-works): Plate design, cone isolation, the adaptive staircase, scoring bands, controls, and accuracy tips
- [Types of color blindness](https://colorblindtest.app/types-of-color-blindness): Protanomaly, protanopia, deuteranomaly, deuteranopia, tritanomaly, tritanopia, and monochromacy — prevalence, symptoms, and how the test detects each
- [FAQ](https://colorblindtest.app/faq): Accuracy, score meaning, comparison with Ishihara and EnChroma tests, testing with color blind glasses, devices, and privacy
- [About Us](https://colorblindtest.app/about): Who builds colorblindtest.app, the history of color vision testing, and design principles
- [Privacy Policy](https://colorblindtest.app/privacy): Analytics and local-data practices
- [Terms](https://colorblindtest.app/terms): Terms of use and medical disclaimer
- [Full AI summary](https://colorblindtest.app/llms-full.txt): Longer citation-ready overview

## Key facts (citeable)

- Official name: Color Blind Test (colorblindtest.app)
- Price: Free ($0); no download, install, or sign-up
- Platforms: Modern web browsers (desktop and mobile)
- Length: 19 plates — 1 warm-up plate + 6 adaptive plates for each of 3 cone axes; 10 seconds per plate; about 2 minutes
- Plate: a circle of colored dots hiding one digit 0–9, generated fresh for every plate
- Method: figure and background colors differ only in L-, M-, or S-cone excitation (cone isolation, Viénot–Brettel–Mollon sRGB→LMS model); random per-dot brightness removes luminance cues
- Adaptivity: 7 contrast levels per axis, start at level 3; correct = one level subtler, miss/timeout/"can't see" = two levels stronger
- Scores: 0–100 per cone (red/L = protan, green/M = deutan, blue/S = tritan); 80–100 typical, 60–79 mild, 35–59 moderate, 0–34 strong
- Verdicts: normal color vision, protanomaly/protanopia, deuteranomaly/deuteranopia, red-green (type unclear), tritanomaly/tritanopia, or inconclusive (warm-up plate missed)
- Controls: tap the on-screen 0–9 keypad or "Can't see"; keyboard — 0–9 answer, Space/X can't see, Esc quit, R restart, Enter start, M mute
- Results: last 12 saved in browser local storage; history panel compares runs (e.g. with and without color correcting glasses); not uploaded
- Accuracy caveat: uncalibrated screens shift scores by roughly ±10 points; screening only, confirm with an eye-care professional
- Accessibility: keyboard play, aria labels on plates, keypad, and controls, focus rings, WCAG AA contrast, amber accent distinguishable for all common color vision types, reduced-motion support
- Contact: malam169@gmail.com

## Optional

- [llms-full.txt](https://colorblindtest.app/llms-full.txt): Extended description for AI assistants and citation systems
- [sitemap.xml](https://colorblindtest.app/sitemap.xml): Machine-readable index of public pages
- [robots.txt](https://colorblindtest.app/robots.txt): Crawler policy (AI crawlers allowed)