How Scoring Works
Color measures how close your guess is to the target — not by comparing raw numbers, but by how different they actually seem to human perception.
The Process
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Convert to Lab color space. Your guess and the target are both converted from HSB to CIELAB, a color model designed to match human perception. Equal distances in Lab correspond to equal perceived differences.
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Measure perceptual distance (Delta E). We calculate the Euclidean distance between the two colors in Lab space. A Delta E of 0 means identical. Under 5 is barely noticeable. Over 50 is a completely different color.
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Map to a score via sigmoid curve. Delta E is converted to a 0-10 score using a sigmoid function. Small distances score high. The curve gets steeper in the middle — the difference between a 7 and an 8 requires much more precision than the difference between a 3 and a 4.
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Apply hue adjustments. Hue is the hardest thing to remember, so we reward getting it right. If your hue is within ~25°, you recover lost points. If it's off by more than 30°, you take a penalty — especially on saturated colors where hue differences are obvious.
The Curve
The sigmoid maps perceptual distance to score. The midpoint sits at Delta E = 38, where scores cross 5/10. Precision matters most above 7 — you need to be very close to earn a high score.
Score (0-10) vs perceptual distance (Delta E). White dot = your current guess in the demo below.
Why Not Just Compare HSB Numbers?
1
Perception isn't linear. A 10% brightness shift on a dark color looks massive. The same shift on a bright color is barely visible. Lab accounts for this.
2
Hue matters more when saturated. Shifting from blue to green is obvious at 80% saturation but invisible at 10%. The scoring adjusts for this — no penalty for "wrong" hue on grays.
3
Getting the family right counts. If you remembered "it was a warm orange" and guessed correctly, that should earn more than guessing the right brightness by accident on the wrong hue. Hue recovery rewards color memory.
Try It
Adjust the guess sliders and watch the score update. The target is fixed — see how close you can get.