Color Blindness Simulator
Preview how an image looks with protanopia, deuteranopia, tritanopia or achromatopsia, using standard colour-transform matrices, beside the original.
🔒 The simulation runs with the Canvas API entirely in your browser — nothing is uploaded. Matrices are standard approximations, not a medical diagnosis.
See how your design looks to viewers with colour-vision deficiency. The image is processed entirely in your browser.
0% is normal vision and 100% the full form. A weak (-anomaly) form at 100% is 64% of the way to its total form, the usual model of it.
Drop an image here or click to choose
Simulate colour vision deficiency
Roughly 1 in 12 men and 1 in 200 women have some form of colour blindness. This tool transforms an image to approximate how it appears to viewers with the main types — protanopia (no red), deuteranopia (no green), tritanopia (no blue), and achromatopsia (no colour) — so you can check whether a chart, UI, or design stays readable.
The image is processed entirely in your browser with the Canvas API and standard colour-transform matrices; nothing is uploaded. Compare the original and simulated versions side by side and download the result. Set “Zoom” past Fit and both pictures show actual pixels or closer, and dragging, scrolling or the arrow keys move them together so the same spot stays lined up. “Model” switches from the default HCIRN matrices to the Machado model, which works in linear light; with no image to hand, “Try a colour wheel” or “Try chart colours” draws a test picture right in the page. An SVG works as well as a photo or a screenshot.
Frequently asked questions
Are these simulations medically accurate?
They use the standard matrices web accessibility tools rely on and are good for design checks, but they are approximations — not a medical diagnosis.
Is my image uploaded?
No. The transform runs with the Canvas API entirely in your browser and the image never leaves your device.
Which type should I test?
Deuteranopia and protanopia (red–green) are the most common, so test those first; tritanopia and achromatopsia are rarer but worth a check for critical visuals.
Can it show milder forms of colour blindness?
Yes. Besides the full forms, the weaker, partial forms of each are listed, and a severity slider moves between normal vision and the full form.
Which simulation model does it use?
By default, the HCIRN matrices, applied straight to the sRGB values. Pick the Machado model under “Model” for the physiological model research tools use: it works in linear light and has its own matrix for each step of severity. Total colour loss is the same grey in both models.