GIFSQ Tools · Module 2 — Food Chemistry & Physicochemical Testing · Tool 35 of 500
Compare two CIE L*a*b* readings and get the CIE76 colour difference ΔE*ab, with the perceptual verdict.
Try sample values — fills the form with the worked example below.
Sample 1 — reference
Sample 2 — test
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ΔE*ab
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ΔL*
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Δa* / Δb*
Equation: ΔE*ab = √((ΔL*)² + (Δa*)² + (Δb*)²), where ΔL* = L2* − L1*, Δa* = a2* − a1*, Δb* = b2* − b1*.
Method: CIE76 colour difference, CIE 15 / ISO 11664-4 — the Euclidean distance between two points in CIE L*a*b* space, measured under the same illuminant and observer.
Assumptions: both readings use the same illuminant, observer and instrument geometry; the samples are opaque and uniform.
Limitations: CIE76 is a simple distance and is not uniform across the colour space — CIEDE2000 fits perception better for small differences; ΔE says how big the difference is, not which way the colour moved; a single ΔE hides the direction (lightness, redness, yellowness).
Rounding: ΔE*ab and each Δ value to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: CIE76 colour difference, CIE 15 / ISO 11664-4 — the Euclidean distance between two points in CIE L*a*b* space, measured under the same illuminant and observer.
Assumptions: both readings use the same illuminant, observer and instrument geometry; the samples are opaque and uniform.
Limitations: CIE76 is a simple distance and is not uniform across the colour space — CIEDE2000 fits perception better for small differences; ΔE says how big the difference is, not which way the colour moved; a single ΔE hides the direction (lightness, redness, yellowness).
Rounding: ΔE*ab and each Δ value to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Reference L* 50.00, a* 10.00, b* 20.00; test L* 52.00, a* 12.00, b* 22.00. ΔL* = 2.00, Δa* = 2.00, Δb* = 2.00, so ΔE*ab = √(4 + 4 + 4) = √12 = 3.46 — clearly visible.
Enter values above to see results.
Perceptual guide: ΔE below 1 is invisible to most people, 1–2 is just noticeable, 2–3 is noticeable, above 3 is clearly visible. These are guides, not a specification. Tool 35 of 500 — GIFSQ
