Delta E: measuring color difference

Every guess is compared against the target color using Delta E — a single number representing how different two colors are. A Delta E of 0 means an exact match; higher numbers mean a bigger difference. It's the same kind of metric printers and paint manufacturers use to check whether a color reproduction is "close enough."

Why CIEDE2000?

There are several ways to compute Delta E. The simplest is just measuring straight-line RGB distance, but that doesn't match how people actually see color — human eyes are far more sensitive to small changes in some colors (like green) than others (like blue). RGB Clash uses CIEDE2000, the current standard formula for perceptual color difference, which weights lightness, chroma, and hue non-uniformly to match human sensitivity instead of treating every color channel equally.

Turning Delta E into a score

Your round score out of 100 is simply 100 minus your Delta E (clamped so it never goes below 0) — the smaller the perceptual difference, the higher the score. This mapping is intentionally simple for now; it may get tuned into a curve that rewards precision even more as more rounds get played and scores get compared against how fair they actually feel.

A couple of examples