Colour Difference Test
Find the one square that is a slightly different shade; the difference shrinks each round
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A colour test in which you find the one square whose shade is slightly different. Each level adds squares and makes the difference smaller, so you can see how far your eyes and your screen can tell colours apart.
How to use
- Under "Rules", choose "60 s (a miss costs 3 s)" or "No time limit (one miss ends it)".
- Press "Start" and press the square with the different colour. A correct answer takes you to the next level.
- At the end, "Level reached" and "Smallest colour difference you found" appear, and your best results are saved.
- Press "Play again" to start another round.
How it works
- The grid starts at 2×2, grows by one row and column every two levels, and stops at 8×8. Reds, greens, blues and greys take turns, and only one of lightness, saturation or hue differs.
- The difference is set with ΔE00 (CIEDE2000), a measure of how different two colours look. It is approximate and computed from the values sent to your screen (8-bit sRGB).
- This is a game for fun, not a colour vision test, and it cannot diagnose colour blindness. Results depend heavily on screen brightness, night mode and your display's colour range. Records are saved in this browser.
Questions and answers
- What is Delta E (ΔE)?
- It is a number that expresses how different two colours look to the human eye; 0 means the same colour. A value around 1 is commonly treated as hard to tell apart even side by side.
- Can this test tell me if I am colour blind?
- No. It is a game whose results change a lot with the screen and the room. See an eye doctor if you are concerned about your colour vision.
- Why do I get different results on my phone and my computer?
- Screens differ in brightness, colour range and calibration, so the same colour values look different. A blue-light filter can make differences look even smaller.
- Which colours are hardest to tell apart?
- It differs from person to person and from screen to screen. Each round shows its colour family and which property differs, so you can see where you miss most often.