Color Blindness Simulator (image & palette)
See a photo or a list of colors as people with red-green (protan, deutan), blue-yellow (tritan) or total color blindness see it, side by side, and find color pairs that become hard to tell apart
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Shows a photo or a list of colors the way people with red-green (protan, deutan), blue-yellow (tritan) or total color blindness see it, next to the original. Use it to check that charts, maps and app screens do not rely on color alone.
How to use
- On "Image", drop or paste a picture. A built-in example is shown first; "Load example" brings it back.
- The original and four simulations appear in a grid. Press "Compare" to lay one over the original with a slider, or "PNG" to save it.
- On "Palette", enter HEX or rgb() values in "Color list", one per line, or pick them with "Add a color".
- Check "Pairs that become hard to tell apart" for pairs with a small ΔE, change the colors and look again.
How it works
- Protan, deutan and tritan use the Machado et al. (2009) model at severity 1.0, applied in linear sRGB. Total color blindness is a grey made from the relative luminance.
- ΔE is the OKLab distance between the two simulated colors × 100; black to white is about 100. Pairs below 10 are marked "hard to tell apart" and below 18 "close"; these thresholds are the tool's own choice.
- Pictures are reduced to 1600px on the long side and processed in the browser only. The color list stays in this browser.
- What a person sees varies. It is safer to combine color with lightness differences, patterns and labels.
Questions and answers
- How do people with red-green color blindness see red and green?
- Both look like similar yellowish browns; red appears darker for protan and brighter for deutan. The bar chart in the example shows this.
- How do I pick chart colors that are safe for color blindness?
- Use pairs off the red-green axis, such as blue and orange, and give each color a different lightness. Enter candidates on "Palette" and change them until no pair is marked.
- What gets confused for tritan vision?
- Blue and green, and yellow against pink or purple, move closer together. It is rare, but worth checking for palettes built on blues and yellows.
- Is the simulation exact?
- It is an approximation that follows a widely used model. The degree of color vision deficiency varies, so no single picture represents everyone.