Color Blindness Test (Ishihara-style)

The Ishihara-style test renders the classic plate format — dot mosaics where numbers hide from certain kinds of color vision — as a design demonstration of what CVD really costs.

What is Color Blindness Test (Ishihara-style)?

The Ishihara plates are the world's most famous color vision test: circles of dots where a number hides in color, visible to typical vision and invisible — or visible wrongly — to deficient vision. The Ishihara-style test renders that format here: a dot mosaic with an embedded figure, shown alongside the simulation of how the plate reads under color vision differences. It is an ishihara plate test online in form, and a design demonstration in purpose.

• The simulation is what makes this version a tool rather than a diagnosis.
• A real Ishihara test answers a clinical question about the viewer; this rendering answers a design question about the image: take the plate and view it through the CVD simulations — the same matrices that power the simulators here — and watch the embedded figure dissolve under protanopia or deuteranopia exactly as it does for viewers with those conditions.
• That is the most visceral demonstration available of what color vision deficiency costs: not muted colors, but information that simply is not there.
• The color blindness test presents the general comparison row; this one stages the classic plate because the format makes the loss undeniable.

• The design lesson travels far beyond plates.
• Any signal encoded only in hue — a red error badge, a green success dot, a chart's red-vs-green series — is an Ishihara plate to someone in the audience: a number that is not there.
• The robustness responses are standard and effective — pair hue with lightness, shape or a label — and the simulators verify the fixes.
• The medical honesty stands: real screening belongs with a professional, whose plates are calibrated and whose administration is controlled.

The plates are famous for a reason worth stating precisely: they test the discriminations that matter most in everyday interfaces, not the ones that are easiest to measure. A plate hides a figure in dots that vary in lightness but not in hue, so anyone whose red-green axis is compressed loses the figure while a typical viewer finds it instantly — and the same construction produces the failure that matters in a chart legend or a status indicator. Reproducing the format digitally allows the simulated view to be shown beside the original, which is where the design lesson lands: the plate stops being a puzzle and becomes a demonstration of what disappears. Used as an ishihara style color test on design work rather than as a screening instrument, the point is the reminder rather than the score. A color blindness plate test run against your own palette is worth more than one run against somebody else's eyesight.

As an ishihara dots demo it is the classic format in service of design empathy: one plate, its simulated disappearances, and the standing reminder that somewhere in the audience, the number is missing.

Running the plate against a real chart or status list, rather than against swatches alone, is where the reminder becomes a change: the hue that disappears is usually carrying a meaning nobody intended to hide.

How to use Color Blindness Test (Ishihara-style)

1. View the plate — typical vision reads the embedded figure; note its value.
2. Switch through the CVD simulations and watch the figure dissolve or survive.
3. Apply the lesson: hue-only signals are plates to someone — add a second channel.

When to use Color Blindness Test (Ishihara-style) vs related tools

Use this to build empathy and demonstrate CVD's information cost vividly. Use the color blindness test for the general comparison, the individual simulators for specific deficiencies, and the friendly picker when the fix is choosing safer colors. For the neighbouring steps, see the color blindness test and the color wheel theory guide.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.

Frequently asked questions about Color Blindness Test (Ishihara-style)