Free web tool
Preview an image with approximate protanopia, deuteranopia, tritanopia, or achromatopsia simulation.
Preview an image through several approximate color-vision-deficiency transforms. The goal is to spot information that becomes hard to distinguish when a design relies too heavily on color alone.
The tool applies common approximation matrices to RGB values. It cannot reproduce every individual’s perception and it is not a diagnostic tool.
Use it as an early design check: “does this distinction disappear when color relationships change?”
Red vs green graph series, success vs error, and selected vs unselected states can become ambiguous when color is the only signal.
Keep labels, icons, patterns, shapes, or text so that the same meaning survives even when colors become harder to distinguish.
Two colors may remain distinguishable in the simulation while text contrast is still too low. The reverse can also happen: text passes contrast requirements but two chart series still look too similar.
Check text/UI contrast separately with WCAG contrast checker.
A design that looks fine in one approximation is not automatically robust for everyone. Cycle through the main modes and watch whether any critical information disappears.
When you fix a problem, adding a non-color cue is usually more reliable than trying to “tune” the original colors for every viewer.