Color Blindness Simulator

See how charts, interfaces and photos may look with protanopia, deuteranopia, tritanopia, achromatopsia and the milder anomalous forms. Compare original and simulated views side by side, use the built-in demo or your own image, and check a palette for colour pairs that become hard to tell apart.

Your files never leave your device.

Loading tool…

Good to know: An approximation based on a published model, not a medical test. Real colour vision varies between people.

How to use the Color Blindness Simulator

1Pick a vision type. For the -anomaly types, set the severity.
2Switch between Original, Simulated and Side by side, or turn the simulation off and on to compare.
3Choose your own image (it is processed on your device, never uploaded), or use the demo dashboard.
4Enter your brand or chart colours in the palette checker to find pairs that become hard to tell apart, and download the simulated image as PNG.

What is the Color Blindness Simulator?

Around 1 in 12 men and 1 in 200 women have some form of colour vision deficiency. In the red–green types (protan and deutan), one kind of cone is missing or shifted, so reds, greens, browns and oranges can look alike; in the rare tritan type, blues and greens and yellows and pinks are confused. Achromatopsia means seeing almost no colour at all.

This simulator applies the matrices published by Machado, Oliveira and Fernandes (2009) in linear RGB, which is the physically correct space for the model; anomalous forms blend between normal vision and the full deficiency by the severity you choose. The palette checker compares colours with the CIEDE2000 difference formula and flags pairs whose difference drops below about 10 after simulation.

Frequently asked questions

Is this a colour blindness test?

No. It shows an approximation of how colours may appear to people with colour vision deficiencies. To find out about your own vision, see an optometrist or use a clinical test such as Ishihara plates under proper conditions.

Which type should I design for?

Deuteranomaly and protanomaly (the red–green types) are by far the most common, so check those first. Don’t rely on colour alone: add labels, patterns, icons or text so information survives any colour vision.

Are my images uploaded?

No. Images are decoded and processed on a canvas in your browser and never leave your device. Very large images are scaled down to keep things fast.

What do the ΔE numbers mean?

ΔE is a perceptual colour difference (CIEDE2000). Around 2 is barely noticeable; below about 10, two colours used side by side in a chart can easily be mistaken for each other.

Is the Color Blindness Simulator free and private?

Yes. The Color Blindness Simulator is free, needs no account, and processes your files entirely in your browser. Files are never uploaded to a server or stored.

All color tools →