Color Blindness Simulator
Upload an image and see exactly how it looks under 7 types of color vision deficiency
Drag & drop an image, or click to upload
About this tool
The Color Blindness Simulator shows you exactly how an uploaded image looks to someone with any of seven types of color vision deficiency — protanopia, deuteranopia, and tritanopia (complete loss of red, green, or blue cone function respectively), their milder anomalous counterparts, and achromatopsia (complete color blindness). Upload an image once and switch between all seven simulations instantly, with the original shown side-by-side for direct comparison. The simulation uses published color-transformation matrices (Machado, Oliveira & Fernandes, 2009) applied in linearized RGB space — the same general approach used by established simulation tools — rather than a naive approximation, so the color shifts it shows genuinely reflect how each deficiency affects perception (reds shifting toward brown/yellow under protanopia, blues and yellows becoming hard to distinguish under tritanopia, and so on). Color vision deficiency affects roughly 1 in 12 men and 1 in 200 women worldwide, overwhelmingly the red-green forms — which makes checking a design against it a real accessibility concern, not an edge case. Everything runs on-canvas in your browser; the image is never uploaded anywhere.
When to use it
- →Checking whether a chart or data visualization's color coding is still distinguishable for red-green color blindness
- →Reviewing a UI mockup or brand palette before it ships to catch color-only signals (error states, status indicators)
- →Understanding what a specific type of color vision deficiency actually looks like, for design education
- →Auditing marketing or product imagery for color-dependent information that colorblind users would miss
Tips
- ◆Deuteranomaly and protanomaly (the anomalous, partial forms) are far more common than full dichromacy — check those first if you're prioritizing which simulation matters most.
- ◆If a design relies on color alone to convey information (red vs. green status, for instance), that's the pattern most likely to break under any red-green deficiency — pair color with an icon, label, or pattern as well.
- ◆Achromatopsia is rare (roughly 1 in 30,000) but useful as a stress test — if your design is still readable in pure grayscale, it's in good shape for contrast-driven accessibility generally.
Frequently asked questions
How accurate is this simulation compared to what someone with color blindness actually sees?
It uses published, peer-reviewed color transformation matrices (Machado, Oliveira & Fernandes, 2009) applied in linear RGB space, the same general method used by established simulation tools — it's a well-regarded approximation, not an exact replica of any individual's vision, since color vision deficiency varies in severity between people even within the same category.
What's the difference between protanopia and protanomaly?
The '-opia' forms (protanopia, deuteranopia, tritanopia) mean complete loss of function in one cone type — no red, green, or blue sensitivity at all. The '-omaly' forms (protanomaly, deuteranomaly, tritanomaly) mean that cone type still functions but with reduced sensitivity, producing a milder version of the same color confusion. Anomalous forms are significantly more common than complete dichromacy.
Is my image uploaded to a server?
No. All simulation happens on an HTML canvas in your browser — the image file itself never leaves your device or gets transmitted anywhere.