Delta Empfindung (ΔE) literally means "difference sensation" in German and denotes the perceived distance between two colors. While simple Euclidean distance in RGB space can measure mathematical similarity, it poorly reflects human vision because the RGB cube is not perceptually uniform. The Delta E family of formulas operates in perceptually uniform color spaces (primarily CIELAB) to produce values that correlate with what we actually see.
Evolution of ΔE Formulas
- CIE76 (ΔE*ab) — Straight Euclidean distance in L*a*b*. Simple and fast but overweights chroma differences in saturated regions.
- CIE94 (ΔE*94) — Adds weighting factors for lightness, chroma, and hue to reduce the over-sensitivity in saturated colors. Application-specific parameters for textiles vs. graphic arts.
- CIEDE2000 (ΔE₀₀) — The current gold standard. Adds rotation term for the problematic blue region, rescales the a* axis for better neutrals, and applies interactive terms between chroma and hue differences.
Practical Thresholds
Industry thresholds for CIEDE2000 are roughly half those of CIE76 because the formula better accounts for how humans perceive small differences:
- ΔE₀₀ < 0.5 — Imperceptible; considered an exact match
- ΔE₀₀ 0.5–1.0 — Requires close inspection to notice
- ΔE₀₀ 1.0–2.0 — Noticeable to trained observer; acceptable for most applications
- ΔE₀₀ > 3.0 — Obvious difference; generally unacceptable in color-critical work
Use in This Platform
Our palette extraction currently uses Euclidean RGB distance (threshold 32) for grouping colors because it runs in the browser without a CIELAB conversion step. For most artwork palettes, RGB distance is sufficient — the goal is coarse grouping, not precision matching. However, Delta E becomes essential when evaluating print reproduction fidelity or comparing artwork palettes across different display profiles.