Color Blindness Simulator

What this tool does

Roughly 8% of men and 0.5% of women have some form of color vision deficiency. This simulator shows what an image or a color pair looks like through each of the three main types, so you can catch interfaces that only differ by hue before your users do.

Simulation uses the Machado, Oliveira & Fernandes (2009) matrices — the same physiologically-based model used in academic visualization research — with an adjustable severity from 0% (normal vision) to 100% (full dichromacy).

Image mode

Drop an image and it renders twice side by side: the original and the simulated version. Pick the vision type and drag the severity slider to see how the image breaks down. The simulated result can be downloaded as a PNG. Decoding keeps EXIF orientation, so photos are not sideways.

Color mode

Two checks for design work:

• Single color — pick any color and see its value under all three types at once, next to the original.
• Pair check — enter two colors and read their CIELAB (ΔE) difference before and after simulation. When most of the difference disappears (below 40%), the pair is reported as indistinguishable and you should fall back on text, icons, or lightness instead. This catches the classic trap where success-green and error-red differ only in hue — a pair that survives luminance-only contrast checks but collapses for red-green color blindness.

All processing happens in your browser; images are never uploaded.