Review color-dependent graphics
Check a chart, map, interface screenshot, status display, or brand graphic under common color-vision deficiencies. Switch the vision type and compare the processed preview with Show before. Severity controls the transition from the original to the full simulation.
The strongest warning sign is not that two colors change. It is that values carrying different meanings collapse into nearly the same appearance.
Protan, deutan, and tritan simulation
Protan conditions affect the long-wavelength response associated with red-green discrimination. Deutan conditions affect the medium-wavelength response and also reduce red-green separation. Tritan conditions affect blue-yellow discrimination.
The simulator applies the published Machado, Oliveira, and Fernandes transformation matrices to linear-light RGB. Severity blends the chosen transform with the identity matrix before the result returns to sRGB. Achromatopsia uses luminance to provide a separate monochrome approximation.
What to inspect
Start with semantic pairs: success and error states, adjacent series in a chart, transit lines, heat-map bands, selected and unselected controls, or warnings against neutral content. Look for pairs that become difficult to separate at full severity.
Then inspect the non-color cues. A red error border still needs an icon or message. Two chart lines need different markers, dash patterns, or direct labels. A map legend needs readable names and boundaries rather than hue alone.
Simulation limits
A matrix produces a representative rendering for a normally sighted reviewer. It cannot reproduce one person’s perception on every display. Monitor gamut, calibration, ambient light, visual adaptation, age, and the degree of deficiency all affect the real viewing experience.
Treat the preview as an early fault finder. Follow it with contrast measurements, keyboard and screen-reader checks where relevant, and review by people who use the finished design.
Example: a red-green status chart
Load the chart and select Deutan at 100%. If the red and green series merge, change more than their hue: add distinct point shapes, label the lines directly, and vary the stroke pattern. Run Protan as a second check, then return Severity to 0% to confirm the added cues still fit the original design.