🟢 Deuteranopia Simulator
See how an image or palette looks with deuteranopia, the most common red-green color-vision deficiency, processed entirely on your device.
Choose an image to see the original and simulated versions side by side. It never leaves your device.
Machado, Oliveira & Fernandes (2009) matrices in linear-sRGB. Approximates average CVD perception. 🔒 Images processed on-device, never uploaded.
How the deuteranopia simulator works
Each pixel or swatch is linearised and multiplied by the published Machado (2009) deuteranopia matrix, then converted back to sRGB; a severity slider interpolates toward milder deuteranomaly. The matrix is a 3×3 transform that collapses the missing green-cone response into the remaining red and blue channels, which is why reds, greens and browns drift toward a shared yellowish look. Setting severity to 100% applies the full dichromat matrix; lower values blend the original and simulated colours to approximate partial green-weakness. Images run on a canvas and are never uploaded.
Deuteranopia (green-weak) is the most common form of color blindness, roughly 6% of men, so it is the first thing to test when red and green carry meaning in a UI or chart.
Frequently asked questions
What is deuteranopia?
Deuteranopia is a red-green color-vision deficiency where the green-sensitive (M) cones are absent, making reds, greens, browns and oranges hard to tell apart. It is the most common type of color blindness.
How common is it?
Deuteranomaly and deuteranopia together affect roughly 6% of men (and far fewer women), making green-weakness the single most prevalent color-vision deficiency.
What should I check for?
That red/green status colors, chart series and success/error states remain distinguishable. If two collapse to the same look, add text, icons or a lightness difference.
Is the image uploaded?
No. It is processed in your browser on a canvas and never sent anywhere.
Can I simulate milder green-weakness?
Yes, the severity slider interpolates between your original and full deuteranopia to approximate deuteranomaly (partial green-weakness).
What is the difference between deuteranopia and deuteranomaly?
Deuteranopia is the dichromatic form, where the green-sensitive (M) cones are effectively absent. Deuteranomaly is the more common anomalous-trichromat form, where those cones are present but shifted, giving reduced green sensitivity. The severity slider models the range between them.
Why test deuteranopia specifically?
Because it is the single most common colour-vision deficiency, a design that stays clear under deuteranopia usually holds up for most colour-blind users. Red/green pairings, pass/fail states, chart series, status dots, are where it bites hardest, so those are the first things to check.
What colours are hardest to tell apart under deuteranopia?
Red versus green is the classic confusion, but it also blurs green versus brown, green versus orange, and some blues versus purples (since purple is red plus blue, and the red part fades). If a chart or map relies on any of those pairs to carry meaning, they can collapse together, the simulator shows exactly which ones.
How do I fix a design that fails under deuteranopia?
Do not rely on hue alone. Add a second cue, text labels, icons, patterns or a clear lightness difference, so meaning survives without colour. For chart series, differ the lightness of adjacent lines and use direct labels; for status, pair a red/green colour with a distinct shape (cross versus tick).