How to See Your Design the Way Colorblind Users Do

You’ve built a chart, a button state, or an infographic that relies on red meaning “bad” and green meaning “good” — and it looks perfectly clear to you. It won’t look clear to everyone. Color vision deficiency affects a meaningful share of people, most commonly as difficulty distinguishing red from green, and a design that leans entirely on that distinction is invisible to exactly the group it’s failing.

The frustrating part is that this is easy to miss in normal design review, because the person reviewing it almost always has typical color vision. You can’t spot a red/green confusion problem by squinting harder at your own screen — you need to actually see an approximation of what a colorblind viewer sees.

What color blindness simulation actually shows you

A simulator takes an image and remaps its colors to approximate how someone with a specific type of color vision deficiency would perceive it. The common types are protanopia and deuteranopia (both affecting red-green distinction, in slightly different ways), tritanopia (affecting blue-yellow distinction, much rarer), and achromatopsia (complete color blindness, seeing only in grayscale). Each produces a visibly different transformation, so a design that fails under one type might be fine under another — you generally want to check more than one.

This isn’t a diagnostic tool and it’s not perfect — it’s an approximation based on how these conditions typically affect color perception — but it’s dramatically more useful than guessing, and it catches the most common failure mode instantly: two colors that look distinct to you collapsing into nearly the same shade.

Why people get stuck here

• Design review skips this by default. Nobody thinks to check color accessibility unless it’s explicitly part of the process, so it often only gets caught after launch, if at all.
• Red/green is everywhere in UI conventions. Status indicators, form validation, charts — red-for-error and green-for-success is such a strong default pattern that it’s easy to lean on color alone without a backup signal.
• It’s genuinely hard to imagine without seeing it. Describing color vision deficiency in the abstract doesn’t convey what actually happens to a specific palette; you need to see your specific image simulated.
• One check isn’t enough. A design that passes a deuteranopia check might still fail under tritanopia, so checking only one type gives a false sense of confidence.

What a good accessibility review looks like

Side-by-side comparison, not just a filtered copy

Seeing the simulated version next to the original makes it obvious exactly which elements lose contrast or distinction, rather than just showing you an altered image with no reference point.

Coverage of more than one deficiency type

Since protanopia, deuteranopia, tritanopia, and achromatopsia affect color differently, checking your image against each type catches more real failure modes than checking just one.

A path to a real fix, not just a diagnosis

Once you spot a problem — two status colors that read the same under deuteranopia — the fix is usually adding a non-color signal: an icon, a pattern, a text label, or a strong enough contrast difference that it survives the simulation.

Common mistakes to avoid

• Relying on color alone to convey status or meaning (error/success, selected/unselected) with no icon or text backup.
• Checking only protanopia or only deuteranopia and assuming that covers “colorblindness” as a whole — the types behave differently enough that they need separate checks.
• Choosing “safe” colors from memory instead of actually simulating them, since two colors that seem intuitively different can still collapse under a specific deficiency type.
• Fixing the simulated image but forgetting to re-check the live design after the color palette changes.
• Assuming grayscale-only visibility (achromatopsia) is too rare to bother checking — it’s a useful stress test even beyond that specific condition, since it also reveals over-reliance on hue alone.

How to do it with Color Blindness Simulator

Online Tool Store’s Color Blindness Simulator processes the image in your browser — nothing is uploaded anywhere.

1. Open the Color Blindness Simulator tool and upload the image you want to check.
2. Select a simulation type: protanopia, deuteranopia, tritanopia, or achromatopsia.
3. Compare the simulated version against the original, side by side.
4. Repeat with the other simulation types to catch failures that only show up under specific deficiencies.

Because it runs locally, it’s a quick way to sanity-check a design mockup, chart, or screenshot before it ships, without uploading it to an external service.

Frequently asked questions

Which type of color blindness should I check first?

Protanopia and deuteranopia (both affecting red-green distinction) are the most common, so they’re a reasonable starting point. If your design has any status colors, checking both of those first will catch the most likely real-world failure.

Does this replace a real accessibility audit?

No. It’s a fast, practical check for one specific issue — color distinction — not a full accessibility review. It’s genuinely useful as an early catch, but a complete audit should also cover contrast ratios, text alternatives, and keyboard navigation.

Can I use this on a screenshot of my actual website, not just a graphic?

Yes — the simulator works on any image, so a screenshot of a live page, a chart export, or a design mockup all work the same way.

Final thought

If a design communicates something important through color alone, a simulator is the fastest way to find out whether that message actually survives for every viewer. Pair the color with a second signal — text, icon, or pattern — and you’ve fixed the problem for good, not just for one type of color vision.

Try the free Color Blindness Simulator