Design Color Cues That Remain Understandable

Design a status so its meaning survives when two hues are difficult to distinguish. A simulation can help reveal a fragile color choice, but it cannot reproduce every person's vision or substitute for feedback from users. Avoid claiming that a single palette is universally color-blind safe.

Start with meaning

Imagine an order list with green and red dots. Without labels, a reader must remember which dot means paid and distinguish it from overdue. Change the rows to a check icon plus "Paid" and an alert icon plus "Overdue". The colors can remain as supporting cues; the words now carry the distinction.

Paid      [check icon]   Invoice 104
Overdue   [alert icon]   Invoice 105
Pending   [clock icon]   Invoice 106

Check readability separately

These checks measure each label against white. They do not prove that green and red are distinguishable from one another. Also test the icons against their surfaces and inspect the actual font size at zoom. Do not show the result as a certificate for the entire interface.

Understand simulation categories

Protan, deutan and tritan simulations model different changes to cone responses. Real differences vary in degree and context. Our simulator transforms sampled palette colors, not a user's display or their complete visual experience. Use several settings to look for lost distinctions, and include grayscale as another diagnostic view.

Review charts and controls

Give chart series direct names and distinct line styles or markers. Label swatches with their values and show selected controls with a check or border. Test whether a colleague can complete the task from a monochrome printout; use the result to locate reliance on color, not to diagnose vision.

Explore the red sample and open its accessibility section to compare simulated swatches. Keep labels visible in the final UI even when the simulation appears clear.