How the scoring works
Most colour games score you on a rough guess. This one uses CIEDE2000, the colour difference formula the printing and textile industries actually use. Your colour and the target are both converted from sRGB to CIE Lab, then compared with the full ΔE00 equation — including the lightness, chroma and hue weighting functions and the blue-region rotation term.
The scale worth memorising:
- ΔE below 1 — invisible to the human eye. The two colours are the same as far as perception is concerned.
- ΔE 1 to 2 — visible only to a trained observer under controlled lighting. Most print specifications target this band for brand-critical colour.
- ΔE 2 to 10 — noticeable when the colours sit side by side.
- ΔE above 10 — clearly different colours.
Bear in mind that you are matching from memory, which is far harder than matching side by side. Averaging under ΔE 8 across five rounds is a strong result. Under 5 is excellent. Under 3 from memory is exceptional and probably means you work with colour professionally.
Why memory instead of side by side
If the target stayed on screen you could simply nudge the sliders until the two swatches looked identical, and the test would measure patience rather than perception. Hiding the target forces you to encode the colour — to hold "slightly warm mid-blue, quite desaturated" in your head — which is the actual skill designers use when they walk from a printed proof to a monitor.
Your screen is part of the result
This matters more than most people expect. An uncalibrated monitor, adaptive brightness, night-shift filters and the ambient light in your room all shift what you see. A score is only comparable to another score taken on the same screen, at the same brightness, in similar light.
If you want to track improvement over weeks, fix those conditions first. Otherwise you are measuring your environment.
This is not a colour blindness test
It cannot be, and neither can any web page. Colour vision deficiency is diagnosed with standardised instruments — Ishihara plates, the Farnsworth-Munsell 100 Hue test — under controlled illumination, by someone qualified to read the result. Scoring badly here means you had a bad round, a dim screen, or a warm lamp. If you have a genuine concern about your colour vision, see an optometrist.
Where to go next
If you want the background on what professional colour testing measures and why designers are usually worse at colour than they assume, read the colour test for designers. If you want the same idea with a camera mode and head-to-head multiplayer, that is Chroma Quest on Android.