BYTETOOLS

Colorblind Image Simulator

Simulate protanopia, deuteranopia, tritanopia and achromatopsia on any image, with a severity slider and reference swatches for accessibility checks.

Drop a chart, screenshot or photo to reviewSimulated pixel by pixel in your browser — nothing is uploaded
100
Deuteranomaly
Simulating
100%
Severity
≈ 6% of men, 0.4% of women
Prevalence

The most common form by a long way. Greens shift toward yellow-brown and reds lose their punch, so red-on-green pairings collapse into one muddy tone.

Reference swatches

Red
Orange
Yellow
Green
Blue
Violet
Grey
Near-black

Top half is the real colour, bottom half is what it looks like with this deficiency. Any two swatches whose bottom halves match are a pairing you cannot rely on to carry meaning.

Add an image above to see the same simulation applied to your own chart or interface.

These are physiological models, not a medical test. They show roughly how colours collapse together for a given deficiency so you can catch designs that depend on hue alone — they cannot diagnose anyone, and real colour vision varies from person to person.

What is the Colorblind Image Simulator?

The ByteTools Colorblind Image Simulator shows how a chart, screenshot or interface looks to someone with a color vision deficiency.

  • Protanopia, deuteranopia, tritanopia and achromatopsia simulations
  • Published Machado 2009 severity matrices interpolated across the whole 0 to 100 per cent range
  • Reference swatch row showing exactly which colors collapse together
  • Transform applied in linear RGB by default, with a gamma-encoded option
  • Original and simulated views shown side by side
  • Prevalence figures for each deficiency plus PNG export of the simulation

How to use the Colorblind Image Simulator

  1. 1

    Drop a chart, screenshot or photo into the upload area.

  2. 2

    Pick a color vision deficiency from the menu — deuteranopia is by far the most common.

  3. 3

    Drag the severity slider between a mild anomaly and full dichromacy.

  4. 4

    Compare the reference swatches: matching bottom halves mean that pair is indistinguishable.

  5. 5

    Check the original and simulated views side by side, then click Download PNG.

About the Colorblind Image Simulator

The ByteTools Colorblind Image Simulator shows how a chart, screenshot or interface looks to someone with a color vision deficiency. It applies the Machado, Oliveira and Fernandes physiologically-based matrices for protan, deutan and tritan deficiencies, plus a luminance-only transform for achromatopsia, to every pixel of the image you drop in.

The severity slider moves smoothly between the published matrices, so you can review the mild anomalous forms as well as full dichromacy — and the mild forms are far more common. A row of reference swatches sits above the image: any two whose simulated halves match are a color pairing you cannot rely on to carry meaning on its own.

Everything is computed 100% locally in your browser on a canvas, so unreleased designs and client screenshots are never uploaded to a server. You can also switch the transform between physically correct linear RGB and gamma-encoded values, which is what several other simulators use, and download the simulated result as a PNG.

Frequently asked questions

What is the most common type of color blindness?

Deuteranomaly, a reduced sensitivity to green light, is by far the most common and affects roughly 6 per cent of men. Protan deficiencies affect about 2 per cent of men, while tritan deficiencies are rare and usually acquired rather than inherited.

How do I check if my chart is colorblind friendly?

Run it through each deficiency in this tool and see whether the series are still distinguishable. If two lines or bars collapse into the same tone, add a second visual channel such as a dash pattern, marker shape or direct label rather than relying on hue alone.

Why does the simulation have a severity slider?

Most color vision deficiency is anomalous rather than total: the affected cone still works but its sensitivity is shifted. The slider interpolates between published matrices so you can review a mild anomaly at 40 per cent as well as full dichromacy at 100 per cent.

Is a colorblind simulator a diagnostic test?

No. These are physiological models that approximate how colors collapse together for a given deficiency, and real color vision varies from person to person. Use it to catch designs that depend on hue alone, not to assess anyone's eyesight.

Are my screenshots uploaded to run the simulation?

No. Each pixel is transformed in your browser on a canvas element and no data is sent over the network. Unreleased designs and confidential dashboards stay entirely on your device.

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