SnapToolsColour Blindness Simulator
Runs in your browserUpload an image to preview how it looks under protanopia, deuteranopia, tritanopia and achromatopsia — all four at once, side by side.
About this tool
Roughly 1 in 12 men and 1 in 200 women have some form of colour vision deficiency, most commonly red-green (protanopia or deuteranopia). This tool re-renders your image through simplified sRGB matrices that approximate each condition, so you can spot places where meaning is carried by colour alone — a red/green status pair, a chart legend, a map — before it ships.
How to use
- Choose an image.
- Compare the four simulated versions against the original.
- Look for information that only the original conveys — that's what needs a second visual cue (an icon, a label, a pattern).
When to use this tool
- Checking whether a chart or infographic still communicates without colour.
- Auditing a status system (e.g. red/green badges) for colour-only meaning.
- Reviewing a map or diagram that relies on colour-coded regions.
- Spot-checking a design before an accessibility review.
Tips
- If two elements are only distinguishable by hue in the deuteranopia or protanopia preview, add a shape, icon, or label as a second cue.
- Achromatopsia (total colour blindness) is rare, but it's the fastest way to check that contrast alone still carries the design.
Limitations
- Uses a widely-used sRGB approximation matrix, not a clinically precise optical model — treat it as a directional check, not a diagnosis.
FAQ
- How accurate is the simulation?
- It uses a widely-used sRGB approximation, the same class of matrix most browser-based simulators use. Treat it as a directional check for where colour-only meaning might fail, not a clinically precise model.
- Is my image uploaded?
- No. The simulation runs on a canvas in your browser; nothing is transmitted or stored.