What are protanopia, deuteranopia, and tritanopia?

They're the three main types of red-green and blue-yellow color vision deficiency. Protanopia is reduced sensitivity to red light, deuteranopia to green light — both make red/green combinations hard to tell apart, and together they affect roughly 1 in 12 men. Tritanopia is much rarer and affects blue/yellow perception.

What is achromatopsia?

Achromatopsia is complete or near-complete color blindness — the world is seen mostly in shades of gray. It's rare, but simulating it is a useful stress test: if your design still communicates clearly with no color at all, color choices elsewhere are working as enhancement, not as the only signal.

Is this simulation medically accurate?

It uses a widely used simplified color transform matrix (the same style used by tools like Coblis) applied directly to the RGB values — it's a good approximation for catching obvious problems like a red/green button pair that becomes indistinguishable, but it isn't a substitute for testing with real users or a clinical simulation tool.

Is my uploaded image sent anywhere?

No. The image is read into the browser with the File API and processed on a element entirely on your device — it's never uploaded to a server.

What should I do if my colors fail?

Don't rely on color alone to convey information — pair it with an icon, label, pattern, or position. Increasing the lightness/contrast difference between colors (not just the hue) also helps across all color blindness types, including achromatopsia.

COLOR BLINDNESS SIMULATOR

See how a palette or image looks under four types of color vision deficiency. Runs entirely on your device.

Your colors

#ff6a35

#2fa84f

#2f8fd8

#e8c93a

#c0392b

Normal vision

Protanopia

Deuteranopia

Tritanopia

Achromatopsia

What each type means

Protanopia — Reduced sensitivity to red light
Deuteranopia — Reduced sensitivity to green light
Tritanopia — Reduced sensitivity to blue light
Achromatopsia — Little to no color perception

How to test for color blindness

1
Choose Color palette to test a set of hex colors, or Upload image to test a screenshot or design file.
2
For a palette, edit the swatches to match your brand or UI colors.
3
For an image, click to upload — it's read locally and never leaves your browser.
4
Compare the Normal vision view against each of the four simulated color vision types.

Questions

What are protanopia, deuteranopia, and tritanopia?: They're the three main types of red-green and blue-yellow color vision deficiency. Protanopia is reduced sensitivity to red light, deuteranopia to green light — both make red/green combinations hard to tell apart, and together they affect roughly 1 in 12 men. Tritanopia is much rarer and affects blue/yellow perception.
What is achromatopsia?: Achromatopsia is complete or near-complete color blindness — the world is seen mostly in shades of gray. It's rare, but simulating it is a useful stress test: if your design still communicates clearly with no color at all, color choices elsewhere are working as enhancement, not as the only signal.
Is this simulation medically accurate?: It uses a widely used simplified color transform matrix (the same style used by tools like Coblis) applied directly to the RGB values — it's a good approximation for catching obvious problems like a red/green button pair that becomes indistinguishable, but it isn't a substitute for testing with real users or a clinical simulation tool.
Is my uploaded image sent anywhere?: No. The image is read into the browser with the File API and processed on a <canvas> element entirely on your device — it's never uploaded to a server.
What should I do if my colors fail?: Don't rely on color alone to convey information — pair it with an icon, label, pattern, or position. Increasing the lightness/contrast difference between colors (not just the hue) also helps across all color blindness types, including achromatopsia.