Is this the same as an Ishihara plate test?

No. Ishihara plates rely on figures hidden in a field of dots and are designed to reveal a specific deficiency. This page simulates what a color would look like, leaving the comparison to you, so it is a self check rather than a screening instrument.

What does it mean if the normal and simulated swatches match for me?

It means the color distinction that the simulation removes is one you were not depending on in that view. It is a useful cue about how much that hue was doing, but it is not a result about your vision and it should not be read as one.

Can it tell me which deficiency I have?

No. It shows four simulated versions of one color and you decide whether any of them look indistinguishable from the original. There is no scoring, no threshold and no output beyond the comparison on screen.

Why does the page show all four deficiencies instead of one?

Because a single color can behave very differently across them, and comparing four swatches at once removes the need to trust any one result. It also makes visible how much of a color's information is carried by the red and green channels, which the two commonest deficiencies affect.

Does uploading an image send it anywhere?

No. The processing happens in the browser on a canvas, so the picture never leaves the machine it was opened on, and nothing is uploaded or stored.

Color Blindness Test

Color

Normal

#3B82F6

protanopia

#5a5ada

deuteranopia

#5650d3

tritanopia

#3fc4bf

achromatopsia

#7a7a7a

Image simulation

Drop an image here, or click to upload

PNG, JPG, WebP, GIF

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Color Blindness Test is a quick color vision self check: it shows one color beside simulations of four common deficiencies so you can spot the ones that look identical to you.

What is Color Blindness Test?

Color Blindness Test is a fast color vision self check rather than a clinical screen. It takes one color, renders it beside simulations of four common color vision deficiencies, and leaves the comparison to you. The useful signal is the opposite of what you might expect: it is the pairing where the normal and simulated swatches look the same that tells you something, because a deficiency the simulation is modelling would be one you cannot distinguish in the same way a viewer with it cannot.

The page lays out a small, fixed set of views:

The original color first, as the reference every other swatch is judged against.
Four simulated swatches, one for each deficiency the engine models: protanopia, deuteranopia, tritanopia and achromatopsia.
Normal and simulated swatches presented in the same row at the same size, so a difference or a match is a single glance away.
An image mode that applies one of the same four simulations to a picture you supply, for the case where a single color is not enough.

Behind the swatches are four fixed three-by-three matrices that recombine the red, green and blue channels, applied directly to the 8-bit values and clamped to the 0 to 255 range. The achromatopsia entry is the only one whose output is guaranteed neutral, because it applies the same luminance weighting to all three channels. Because every matrix is applied at full strength, what you are comparing against is a complete deficiency rather than a graded one, and the page shows all four at once so no single result has to be trusted on its own.

The limits follow from it being a self check rather than a test with a score.

It is not a diagnosis. Recognising a color in a simulation is not a measure of your vision, and nothing here should be read as one.
It cannot tell you which deficiency you may have. It shows four versions of a color and you decide whether one of them is indistinguishable, which is a subjective comparison and not a result.
One color at a time, so checking a whole palette means working through it entry by entry.
The simulations are full deficiencies. A mild anomaly, which is by far the more common case, may see a clear difference that the swatch does not show.
Nothing is scored, stored or compared over time, and no history is kept between visits.

Use it as a first look at a color you are unsure about, and as a way to get a feel for how much information a hue actually carries once a channel is removed. If two swatches match for you, treat that as a cue to separate the colors by lightness rather than as a finding about your eyes, and if you need more than a cue, the full simulation view and the image simulation give you a broader comparison to work from.

As a form of cvd screening it is deliberately shallow, and that is the honest description of the page. It produces a view rather than a score, so it will not tell you where on a range you sit or whether you should seek further advice. What it does well is make the loss of information visible on a single screen, which is often enough to change how a chart, a legend or a status color is set up.

How to use Color Blindness Test

Choose a color in the swatch field, ideally one from a palette you are already working on.
Read the row from left to right, comparing the original against each deficiency in turn.
Note any pair where the normal and simulated swatches look indistinguishable to you, since that is the cue the page produces.
Switch to the image panel and run your most color-dependent screen through one of the simulations to check the same question in context.

When to use Color Blindness Test vs related tools

Use the color blindness test when you want a quick self check of how a single color reads across several deficiencies in one view. The wider comparison, including the image simulation across all four types, is the color blindness simulator; a one-to-one comparison for a specific deficiency is the protanopia simulator or deuteranopia simulator; and choosing text colors that hold up once hues are gone belongs with the color blind friendly color picker.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.