Three short tests that look at your color vision from different angles. Together they point to which cone type is affected (red, green or blue) and roughly how strongly.
Before you start: turn off Night light, f.lux, True Tone, any blue-light filter and any color-blindness filter, set brightness to normal, and sit about an arm's length from the screen. A monitor isn't a calibrated clinical instrument, so treat the result as a well-informed guess and confirm it with an optometrist (an anomaloscope test settles the exact type).
A ring shaped like the letter C is hidden in the dots. It differs from the background only in color; brightness is scrambled so you can't use it as a clue. Say which way the opening faces. When you can't see a C, say so instead of guessing. The color gets fainter as you succeed and stronger when you miss, separately along the red, green and blue confusion lines.
Keys: ← ↑ → ↓ for the opening, Space for "can't see".
About 45–65 trials.
Starting from the fixed reference cap on the left, pick the cap that looks most similar to the last one you placed, and keep going until the tray is empty. Click a placed cap to send it back. People with a color deficiency tend to jump across the color circle along their own confusion line, and the direction of those jumps reveals the type.
Strips A, B and C are the reference recolored the way people with each kind of dichromacy see it. A person with that type sees their own strip as identical to the reference; others look different. Rate each strip honestly, comparing swatch by swatch.
Simulation: Machado, Oliveira & Fernandes (2009), blended linearly for partial strength. Color boost: Fidaner daltonization (a blue-channel variant for tritan). Photos from Wikimedia Commons, CC0 / public domain; see img/CREDITS.md. Tap a photo to see it full screen.
Windows, iPhone, Android and Mac have a built-in color filter for color-blind users that recolors everything on screen so confused colors become easier to tell apart.
| Type | Affected cone | What it's like | Prevalence |
|---|
Prevalence figures are for people of Northern European descent; red-green types are X-linked, so they're about 20 times rarer in women. Tritan types are not sex-linked.