Color Blindness Simulator
The Color Blindness Simulator transforms any image you upload to show how it looks to someone with one of the main types of color blindness, using a published scientific mathematical model (Machado et al., 2009) applied correctly in linear color space, not a simplified approximation. Supports four types: protanopia (red-blind), deuteranopia (green-blind), tritanopia (blue-blind), and achromatopsia (total color blindness). Very useful for graphic and chart designers to make sure their design is understandable to all users before publishing it. All processing happens in your browser via Canvas — your image is never uploaded to a server.
Your image is processed on your device via Canvas and is never uploaded to our servers.
This tool simulates how your image would look to someone with one of the main types of color blindness, using published scientific research (the Machado et al. 2009 model). Useful for checking a design or chart's color accessibility before publishing it.
The simulation is approximate and based on a scientific mathematical model, not a 100% exact match for any individual's experience — the severity of color blindness varies from person to person even within the same type.
Drag an image here or choose one
JPG, PNG, or WebP
What this tool does
Shows how your image appears to people with colour vision deficiency, across four types: protanopia, deuteranopia, tritanopia and achromatopsia.
When to use it
- A design or chart you want comprehensible to every user.
- An interface using colour to distinguish states.
- Educational or informational material that relies on colour.
- Testing a map or diagram before publishing it.
How to use it
- Put the image on the drop area or choose it.
- Choose the type to simulate.
- Compare the result with the original, and download it if you want.
A practical example
Input
A chart distinguishing its two lines by red and green.
Output
A simulation showing the two lines in near-indistinguishable colours — which is what a considerable proportion of men see.
This is the commonest charting mistake: relying on red and green alone to distinguish. Add a difference in shape or pattern, not only in colour.
Limitations
- The simulation is a scientific approximation of what people with these conditions see and does not perfectly represent any one person's experience, since severity varies.
- It simulates and does not propose alternatives; the fix is a design decision you make.
- Passing the simulation does not replace a contrast check; use the Colour Contrast Checker as well.
Privacy and processing
Your image is processed on your device via Canvas and is never uploaded to our servers.
Technical notes
- The simulation uses the Machado, Oliveira & Fernandes (2009) physiologically-based model of colour vision deficiency, at full-severity dichromacy, cross-verified against the authors' own supplementary data, Chromium's shipped DevTools implementation and the colour-science library — all three agreeing to full published precision.
- Achromatopsia falls outside that model's scope, being a loss of all cone function rather than a dichromatic confusion, so it uses the standard linear-luminance approach instead.
Frequently Asked Questions
No — all processing happens in your browser via Canvas; your image is never uploaded to a server.