Free Color Blindness Test

What a dot plate screening can and cannot tell you

Colour vision starts with three types of cone cell in the retina, each most sensitive to a different band of wavelengths. When one of those three responds differently than usual — or is missing altogether — some pairs of colours that most people separate easily collapse into the same sensation. The person is not seeing in grey. They are seeing a world with fewer distinct hues in one region of the spectrum, and because they have always seen it that way, they usually have no idea anything is different until a test like this one tells them.

The dot plate is a clever way of getting at that. A number written in ordinary ink would be readable by anyone, because the ink is darker than the paper. So the plate removes every clue except hue. The digit is drawn out of dots that differ from their neighbours in colour but sit at almost the same brightness, and the dots are deliberately irregular in size and position so that no edge or texture gives the shape away. If your visual system separates the two hues, the digit assembles itself instantly. If it does not, you see an even field of speckle.

How the 12 plates in this screening are built

Every plate here is generated in your browser rather than loaded as a picture. A digit is laid out on a fine grid, several hundred dots of varying radius are scattered across a circle, and each dot takes its colour from one of two palettes depending on whether its centre falls inside the digit. Both palettes carry a spread of shades, so no single dot is a reliable clue — only the population of dots as a whole is.

The twelve plates are not all the same kind. Three are controls, drawn with a genuine brightness difference between figure and ground; they are legible to essentially everyone, including people with a complete colour deficiency, and they exist to confirm that your screen and your attention are working. Six probe the red-green axis, the one involved in the common inherited deficiencies. The remaining three probe the blue-yellow axis, which is far rarer and behaves quite differently. Because the plates are separated this way, a result that is weak in only one family is much more informative than a bare total.

Reading your score

Your score is simply the number of plates you read correctly, out of twelve. Treat the bands below as rough guidance rather than a verdict, and pay more attention to the per-family breakdown shown with your result than to the single number.

Why your screen matters more than you think

Plate tests were designed for printed cards viewed under standardised daylight. A screen is a different instrument entirely. Two monitors can render the same hex value as visibly different colours; a phone in automatic brightness quietly warms its whites at dusk; and any night-shade mode strips out exactly the blue component that the blue-yellow plates depend on. A dark room shifts your own adaptation as well. None of this is fatal for a screening, but it is why an online result can never be a diagnosis, and why a borderline score usually deserves a second run under better conditions before you conclude anything.

If you want the most honest attempt: use a laptop or desktop rather than a phone, set brightness near maximum, turn off any colour filter or accessibility adjustment, sit in a normally lit room rather than a dark one, and answer within a few seconds of each plate appearing. Staring at a plate for half a minute lets you reason your way to a shape from partial cues, which produces a score that flatters you and tells you less.

What happens after a low score

An eye care professional will not rely on plates alone. They may use an arrangement test, where you order a row of caps by hue and the pattern of your errors maps the axis of confusion, or an anomaloscope, which asks you to match a yellow light by mixing red and green and measures the ratio you settle on. Those tools separate the type and the severity — whether a cone is shifted or absent, and how much. Inherited red-green deficiency is not treatable, but it is very manageable once named: it explains a lifetime of small frictions, it matters for a handful of careers with colour-critical licensing, and children benefit enormously from teachers who know before a maths worksheet is colour-coded.

How this differs from a hue arrangement test

A plate screening asks a yes-or-no question: can you separate these two hue families at all? An arrangement or hue-ordering test asks a finer one: how precisely can you rank shades that are already close together? The second is more sensitive to mild deficiency and to acquired changes from ageing or medication, but it is slower and far more punishing on a mismatched screen. Starting with plates is the sensible order — they are quick, they are robust, and a clean pass across all three families makes a significant deficiency unlikely.