Color blindness simulator.

Machado, Oliveira and Fernandes (2009), "A Physiologically-based Model for Simulation of Color Vision Deficiency": the authors' published matrices, one per severity in tenths, applied to linear RGB (the image is decoded from sRGB first and encoded after). Achromatopsia is the relative luminance alone.

Deuteranomaly and deuteranopia (green cones shifted or missing) and protanomaly and protanopia (red cones) make up red-green color blindness, about 8% of men and 0.5% of women. Tritanomaly and tritanopia (blue cones) are rare, and achromatopsia, seeing no color at all, is rarer still.

An -anomaly is a shifted cone, and it comes in degrees, so the simulator lets you set its severity (60% by default). An -opia is a missing cone, always shown at full strength.

Type or paste colors, one per line or separated by commas, in any CSS notation. Each type's row shows them as that viewer sees them, and pairs that come within a small perceptual distance (ΔE OK under 0.05) are listed as hard to tell apart, the usual problem with red and green status colors or chart series.

Drop an image: the original and the simulation sit side by side, with every type as a thumbnail to switch between, and the simulated picture downloads as a PNG.

No simulation is exact for every person; it shows the typical effect. Use it to catch colors that carry meaning alone, and pair color with text, shape or position so nobody depends on hue.

No. Images and colors are processed in your browser and never uploaded.

No. The "Color blindness simulator" tool is free and opens without a sign-in, an account or an install.

Nothing. The "Color blindness simulator" tool holds your input in the page's memory, so closing or reloading the tab clears it, and it saves nothing in this browser.

Closest to the "Color blindness simulator" tool: Contrast checker, Color palette generator, Image color palette generator, Tailwind color generator. Each opens on its own page, free and in the browser.

The "Color blindness simulator" tool is one of 17 in its group. The group's page, /tools/color, lists them all.

The tool is free. Its interface is built from shadcn.io's own components (Button, Input, Slider and the rest of the registry under /ui), which come in React, Vue, Svelte and Solid. Pro adds the blocks and templates for the product around it.