Color Blindness Simulator

How to use the color blindness simulator

1. Choose or drop an image. A sample chart with the classic red and green problem is loaded to start.
2. Compare the four simulations with the original.
3. Type HEX values to check a palette in the same way, row by row.
4. Download any simulation as PNG to share in a review.

The kinds of color vision deficiency

Most color vision deficiency is inherited and affects the red and green cone cells. Deuteranomaly and deuteranopia (green) are the most common, followed by the red types. Blue-yellow deficiency (tritan) is rare, and seeing no color at all is very rare. Far more men than women are affected, because the genes for the red and green cones sit on the X chromosome.

The simulations use the Machado, Oliveira and Fernandes (2009) model at full severity, applied in linear RGB. They show the strongest form of each type; many people have a milder version, so treat the results as a worst case.

Fixes that work for everyone

• Never use color as the only signal. Add labels, icons, patterns or position.
• Pair hues that also differ in lightness, such as dark blue with light orange, instead of red with green.
• Label chart lines directly instead of relying on a color legend.
• Check text contrast separately in the contrast checker.

Questions