Color Blindness Simulator
Preview how your image looks to viewers with different types of colour vision deficiency.
Colour vision deficiency affects a significant share of people — most commonly men — and it can make red/green or blue/yellow distinctions vanish. This simulator re-renders your image the way it would appear under different types of colour blindness, side by side with the original, so you can check whether a chart, map, or design still makes sense. It runs on a canvas in your browser; nothing is uploaded.
The main types it simulates
The simulation covers the common forms of colour vision deficiency: protanopia and deuteranopia, the two red–green types where reds, greens and browns blur together, and tritanopia, the rarer blue–yellow type. Each transforms the image's colours to approximate what someone with that condition perceives. Red–green types are far more common, so if you only check one, checking a red–green simulation catches the majority of real-world problems.
How to act on what you see
If two categories in a chart become indistinguishable in the simulation, colour alone is carrying the meaning — the fix is to add a second cue: labels, patterns, different shapes, or clearly different brightness levels rather than just different hues. The classic trap is a red/green “good/bad” scheme, which is exactly the pair that collapses for most colour-blind viewers. Treat this as an approximate design check: it models colour perception well but cannot capture every individual's vision, so use it to catch obvious failures, not as a medical or certified accessibility test.
Frequently Asked Questions
Which types of colour blindness does it simulate?
Protanopia and deuteranopia (the two red–green types) and tritanopia (blue–yellow). Red–green is the most common, so it catches most real-world issues.
What should I change if colours become indistinguishable?
Add a second cue beyond colour — labels, patterns, shapes, or distinct brightness. Avoid relying on a red/green contrast, which collapses for most colour-blind viewers.
Is this a medical or certified accessibility test?
No. It is an approximate design aid that models typical colour perception. It is great for spotting obvious problems but is not a diagnosis or a formal accessibility audit.
Is my image uploaded?
No. The simulation is computed on a canvas in your browser, so the image stays on your device.