TOOL · COLORS
Color blindness simulator for images
Drop the design, chart or photo and see side by side how about 8% of men and 0.5% of women see it — before finding out your red-and-green chart is unreadable for part of your audience.
Processed in your browser — your files never leave your computer.
How it works
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Drop your image here
Drag a .jpg, .png or .webp up to 20 MB onto the dotted area, or click to choose. Works with interfaces, charts, maps, photos — any image.
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Compare the four versions
The tool builds a 2×2 grid: the original plus protanopia, deuteranopia and tritanopia simulations, each labeled. The conversion uses the scientific Viénot/Brettel matrices, pixel by pixel.
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Download what you need
Each version has its own PNG download button — handy for accessibility reports or showing the team.
Frequently asked questions
What are protanopia, deuteranopia and tritanopia?
They are the three types of dichromacy — when one of the eye's three cone types does not work. Protanopia lacks the red-sensitive cone; deuteranopia, the green one (the most common); tritanopia, the blue one (quite rare). In the first two, red and green look very similar; in tritanopia, blue and green get confused.
Is the simulation scientifically accurate?
It uses the Viénot, Brettel & Mollon (1999) method, the reference in the field, applied in linear RGB as the theory requires. It is a faithful approximation of full dichromacy — milder forms (like deuteranomaly) see more color than the simulation shows.
What is simulating color blindness for?
To test whether your material works for everyone: charts that rely on green vs. red, heat maps, colored status indicators, teaching material. If the information disappears in the simulation, add labels, icons or patterns beyond color.
How many people see like this?
An estimated 8% of men and 0.5% of women have some color vision deficiency — millions of people. The vast majority are on the red-green spectrum (protan/deutan).
Why does the download come as PNG?
PNG preserves every pixel with no further compression — important in a simulation that is precisely about exact colors. The longest side is capped at 1400 px so the simulation runs light in the browser.
Is my image uploaded to a server?
No. The simulation runs entirely in your browser, on your device. The image never leaves your computer.