Colori

Color Vision Science

Where does your color world end?

Every person's color perception is subtly different — and the boundaries of what you can distinguish shift across the color spectrum. Near yellow, your eye is extraordinarily precise. In the purple-blue range, the threshold is much larger.

In 1942, David MacAdam showed that around any given color there exists an ellipse of colors you cannot distinguish from it. Colori extends this classical work into the full three-dimensional color space, probing 35 locations across the visible gamut.

Every game you play generates real psychophysical data — thresholds, reaction times, and discrimination sensitivity along three cardinal axes: red–green, blue–yellow, and black–white. With enough players, the picture becomes a map.

reference colors probed per game, on a BCC lattice in RGB space

fixed directions in CIELAB color space per location

ΔE difficulty levels from barely perceptible to obvious

discrimination ellipsoids, one per color location, shape your score

Gameplay

Simple to play.
Deep in science.

Each round lasts seconds. Over 35 rounds you cover the full RGB color cube, generating a personal map of your color discrimination ability.

STEP 01

🎨

Find the odd discs

A reference color is shown. A field of discs appears — most match the reference, but some are shifted in CIELAB color space. Tap every disc that looks different.

STEP 02

⚡

Speed and precision

Subtle differences earn more points. Tap quickly during the green phase for double points. Each error costs a life — precision matters as much as speed.

STEP 03

📊

See your sensitivity

After every 7 rounds, a summary shows your red–green, blue–yellow, and lightness sensitivity. After the full game, discover your personal color profile.

Peer-Reviewed Research

The science behind the ellipsoids

The three-dimensional structure of color space has been mapped by measuring discrimination ellipsoids — regions of colors around a reference that observers cannot distinguish from it — at 35 locations arranged on a body-centered cubic lattice within the sRGB cube.

The rotating visualization you see on this page places one ellipsoid at each of those 35 locations. Their colors are the actual reference colors; their sizes reflect how large the discrimination region is at each point. Near neutral grays, the ellipsoids are larger. Near saturated primaries, they are smaller and more elongated.

This work extends the classical 2D discrimination ellipses of MacAdam and Wyszecki & Fielder into a complete empirical 3D metric field — the first of its kind across the full color gamut.

Red–Green

Sensitivity along the a* axis. Typically the sharpest for normal observers.

Blue–Yellow

Sensitivity along the b* axis. Varies most between individuals.

Lightness

Sensitivity along L*. Largest and most elongated discrimination regions.

bioRxiv Preprint

An empirical three-dimensional metric field for color space

Jan Koenderink, Andrea van Doorn, Doris I. Braun & Karl R. Gegenfurtner

bioRxiv · March 11, 2026 · DOI: 10.64898/2026.03.09.710376

We measured discrimination ellipsoids at 35 reference colors distributed on a body-centered cubic lattice within the sRGB unit cube, probing 26 directions in CIELAB space per location. The resulting metric tensor field reveals systematic variation in color sensitivity across the gamut — larger, rounder ellipsoids near the achromatic axis, smaller and more elongated near saturated hues. This constitutes the first complete empirical 3D color discrimination metric, extending MacAdam's classical 2D results into the full color solid.

Read the preprint

Research Group

Built at a world-leading vision lab

Colori is developed by the Allgemeine Psychologie group at Justus-Liebig-Universität Gießen — one of Europe's leading centers for visual psychophysics and color science.

Justus-Liebig-Universität Gießen

Abteilung Allgemeine Psychologie
Prof. Dr. Karl R. Gegenfurtner

This project was supported by European Research Council ERC AdG Color 3.0 (884116), by DFG Sonderforschungsbereich SFB/TRR 135 (222641018), and by DFG Excellence Cluster EXC 3066/1 “The Adaptive Mind” (533717223).

ERC Advanced Grant Color 3.0

DFG SFB/TRR 135 Cardinal Mechanisms of Perception

DFG Excellence Cluster EXC 3066/1 The Adaptive Mind

Ethics approval LEK-2026-0039. Data are collected with participant consent for scientific research purposes.