About the Color Blind Test
This tool brings together four established colour-vision screening methods in one place: Ishihara plates, a hue-discrimination task, an anomaloscope-style colour match, and a Farnsworth D-15 arrangement. Together they give a fuller picture than any single test, and everything runs privately in your browser.
What each test looks at
The Ishihara plates are the classic screen for red-green deficiency: a number is hidden in coloured dots that share the background brightness, so only the hue distinguishes it. The hue-discrimination rounds ask you to spot the one chip whose hue is shifted, with the shift shrinking each round to probe how fine your discrimination is. The colour-matching test recreates the principle of a Rayleigh match, where you slide to recreate a target colour; the range of positions you accept reveals a lot about anomalous trichromacy. The Farnsworth D-15 has you order colour caps by hue, and the pattern of any mistakes points toward a specific confusion axis (protan, deutan, or tritan).
An honest word on accuracy
This is a screening aid, not a diagnosis, and it is important to be clear about why. Real clinical plates are printed under controlled conditions, whereas a screen renders colour differently depending on its gamut, brightness, calibration, and the light in your room. Those variables can shift results in either direction. So a result here is a useful prompt, not a verdict. If colour vision matters for your job, a licence, or a medical question, the only reliable answer comes from physical, calibrated testing performed by an eye-care professional. If this tool flags a possible deficiency, treat that as a reason to book a proper examination, not as a conclusion.
Privacy and how to use it
All four tests are generated and scored locally with JavaScript and an HTML canvas; no image or answer ever leaves your device. For the most meaningful results, use neutral lighting, keep your screen at a normal brightness, and switch off any blue-light or night filters. Answer as honestly as you can — not being able to see a difference is itself a valid and informative result. Colour-deficient vision is common, affecting roughly one in twelve men and far fewer women, and most people who have it live without significant difficulty.
Frequently Asked Questions
How do the Ishihara plates work?
Each plate is made of coloured dots where the hidden number and the background share the same brightness but differ in hue along a red-green confusion axis. People with normal colour vision see the number; those with red-green deficiency see only a uniform field of dots.
What does the colour matching test measure?
It mimics an anomaloscope Rayleigh match. People with normal colour vision lock in at a precise slider position; those with anomalous trichromacy accept a wider range, and dichromats accept almost any position.
What is the Farnsworth D-15 test?
You arrange 15 colour caps in hue order from a fixed anchor. Colour-deficient users tend to make characteristic transposition errors along their specific confusion axis.
How accurate is an online test like this?
It is a reasonable screening, not a clinical instrument. Your screen gamut, brightness, calibration, and room lighting all affect the result, so it cannot replace a professional examination. For employment, medical, or aviation requirements, get tested with physical, calibrated plates by an eye-care professional.
Is my data private?
Yes. Every test runs entirely in your browser using JavaScript and a canvas. Nothing is uploaded, stored, or sent to any server.
Can colour blindness be cured?
Inherited colour vision deficiency has no cure. Tinted lenses can enhance contrast between confusable colours for some people, and most people with a deficiency adapt and live without major difficulty.