Color Blindness Simulator

What this color blindness simulator does

Around 1 in 12 men and 1 in 200 women have some form of color vision deficiency, so a design that relies on color alone to communicate — a red/green status indicator, a chart with similar hues, a low-contrast call-to-action — can be invisible or confusing to a meaningful slice of your audience. This tool uploads an image and renders it through eight different color vision profiles side by side, so you can actually see what changes instead of just reading about it in the abstract. Every calculation happens locally on canvas in your browser; nothing is uploaded anywhere.

How to use it

• Upload a screenshot, chart, mockup, or photo.
• Compare the original against protanopia (no red cones), deuteranopia (no green cones), tritanopia (no blue cones), and achromatopsia (no color perception at all) — the four full dichromacy/monochromacy types.
• Turn on "Also show -anomaly variants" to add the milder, far more common partial forms — protanomaly, deuteranomaly (the single most common type, affecting roughly 5% of men), and tritanomaly — blended at a realistic severity rather than the full effect.
• Download any individual variant as a PNG to drop into a design review or accessibility report.

Real-world use cases

Checking whether a chart's color-coded legend is still distinguishable once red and green start looking similar. Reviewing a UI mockup before handoff to catch a status badge or error state that relies on color alone. Testing a logo or infographic for a client who's specifically asked about accessibility compliance.

Frequently asked questions

Is this simulation medically precise?

It uses widely-used approximate transform matrices for each deficiency type, the same style of approximation used by most browser-based color blindness tools. It's accurate enough to catch real design problems, but isn't a substitute for a clinical color vision test.

What's the difference between deuteranopia and deuteranomaly?

The "-opia" forms (protanopia, deuteranopia, tritanopia) are the complete absence of a cone type. The "-anomaly" forms (protanomaly, deuteranomaly, tritanomaly) are a weakened, partial version of the same deficiency — much more common, and shown here at a realistic blended severity rather than the full effect.

Which type of color blindness is most common?

Deuteranomaly (weak green cones) is by far the most common, affecting roughly 5% of men. Full dichromacy types like protanopia and tritanopia are much rarer.

Does my image get uploaded to a server?

No. The file is read and processed entirely in your browser using the Canvas API — it never leaves your device.

Why does the achromatopsia version look completely gray?

Achromatopsia is complete color blindness — vision based on brightness (luminance) only, with no color perception at all. It's extremely rare, but useful as the extreme end of the spectrum for comparison.