Choose an image below. It is read, drawn and discarded in this page — it is never uploaded.
Color Blindness Simulator
An approximation of how an image reads to other eyes, using a published model — with your picture staying on your own device.
What this is
Around one man in twelve and one woman in two hundred has some form of color vision deficiency, most often a difficulty telling reds from greens. Designs that carry meaning in color alone — a red line against a green one, a status dot, a chart with no labels — can become unreadable to them while looking fine to everyone else.
This page applies a published model to your image so you can see an approximation of that. It is a useful check on a chart, an interface or a slide before you send it.
What it is not
It is an approximation, not a test. It does not measure anyone's vision, it cannot tell you whether you or anyone else has a color vision deficiency, and it is not a diagnosis or medical advice. If you want to know about your own vision, that is a question for an optometrist, who has instruments for it.
It also shows the severe form of each type. Many people have a milder version, and two people with the same label do not see identically. Treat the result as "roughly what changes", not as a window into someone's eyes.
The model, and where it comes from
The three transformations are the severity-1.0 matrices published with A Physiologically-based Model for Simulation of Color Vision Deficiency by Gustavo M. Machado, Manuel M. Oliveira and Leandro A. F. Fernandes, in IEEE Transactions on Visualization and Computer Graphics 15(6), November/December 2009, pages 1291–1298. They were taken from the authors' own page for that paper on 23 September 2026, and they are applied in linear light, which is where the model operates.
Nothing about those numbers was invented or adjusted here, and if the source changes them, this page should change too.
What to do with what you see
Look for meaning that disappeared. If two lines on a chart became the same color, the chart needs labels, patterns or different values — not a different palette.
Check contrast separately. Color vision is one axis; lightness is another. The Contrast Checker covers the second.
Build with lightness differences, which survive every kind of color vision. The Palette Generator's tints and shades are a way in.
Your image stays on your device. This page reads it, draws it and forgets it: there is no upload, no storage, and no request to anyone. Leaving the page discards it immediately.