Color Blindness Simulator
See how people with color vision deficiency see your design.
What is color blindness?
Color blindness is a common name for color vision deficiency, also called dyschromatopsia. It affects about 8% of men and 0.5% of women, with prevalence varying between populations. It usually results from a malfunction of one of the three retinal cone types: L, M and S, sensitive respectively to long, medium and short wavelengths of light. Red-green deficiencies dominate, with deuteranomaly being the most common form. People with deuteranomaly or deuteranopia may have trouble distinguishing greens, reds and browns, as well as oranges, purples, pinks and grays.
Why should designers test for color blindness?
Typical design pitfalls include red call-to-action buttons on green backgrounds, maps with red-green legends and charts where color is the only information. For hundreds of millions of people worldwide, with estimates reaching around 300 million, such designs can be difficult or impossible to read. Simulation lets you catch issues early, before they reach print, signage or campaigns.
How does the simulator work?
The simulation uses the Machado, Oliveira & Fernandes model from 2009 (IEEE TVCG), a physiologically-grounded algorithm defined for 11 severity steps (0–100% in 10% increments) independently for protanopia, deuteranopia and tritanopia. Intermediate slider values are interpolated between the two nearest matrices from the paper. Matrices are applied in linear RGB (with sRGB gamma decoding on input and re-encoding on output), giving faithful reproduction especially in midtones and shadows. For achromatopsia we apply Rec. 709 luminance coefficients in linear space. This is a visual simplification; real achromatopsia also involves symptoms such as photophobia and reduced visual acuity, and anomalous trichromacy (protanomaly, deuteranomaly, tritanomaly) has individual, non-uniform severity.
