Colour Blindness Simulator
Upload a photo, chart, map or design and see it side by side as people with each type of colour vision deficiency see it. Check whether a palette still works for the 1 in 12 men with red-green colour blindness. The image is processed in your browser and never uploaded.
Check a colour palette
Paste hex colour codes (#rrggbb), separated by commas or spaces, to see each colour under every type and find pairs that become hard to tell apart.
How to use it
- Choose an image, drop it on the box or paste it, or use the sample chart.
- Click a type to see it large, and adjust the severity; hold the eye button to compare with the original.
- Download the simulated PNG, or paste your palette below to check which colours get confused.
Frequently asked questions
How accurate is this simulation?
It uses the models recommended in the scientific literature: Machado, Oliveira and Fernandes (2009) for red and green deficiencies, with real severity levels, and Brettel, Viénot and Mollon (1997) for blue, computed in linear RGB. Results match the DaltonLens and colorspacious reference libraries. Individual vision varies, so treat it as a close approximation.
How common is colour blindness?
Red-green colour blindness affects about 8% of men and 0.5% of women of Northern European ancestry; most of them have a mild form (anomalous trichromacy). Blue-yellow deficiency and complete colour blindness are rare.
How do I make charts readable for colour-blind people?
Do not rely on colour alone: add labels, patterns or different line styles. Avoid pairing red with green, and choose colours that also differ in lightness. Palettes designed for colour vision deficiency, such as Okabe-Ito, are a safe start; check yours with the palette tool on this page.
◐ Colour Contrast Checker
🌈 Colour Palette Generator
Machado, Oliveira & Fernandes (2009) — CVD simulation
DaltonLens — Review of open source color blindness simulations
Wikipedia — Color blindness