Color Measurement (Lab) Calculator

CIE76 is a simple Euclidean distance in L*a*b* space that treats lightness, chroma, and hue differences as equally weighted, while CIE94 rescales the chroma and hue components using factors that depend on the reference sample's own chroma. This reweighting corrects for the eye's lower sensitivity to hue and chroma shifts in highly saturated colors, so CIE94 typically reports a smaller, more perceptually accurate difference than CIE76 for vivid samples.

ΔC*ab is the difference in chroma, or saturation and vividness, computed as the square root of a² + b² for each sample, while ΔH*ab is the leftover hue-angle-driven difference once lightness and chroma are accounted for. Reporting these separately lets you diagnose whether two samples differ mainly in how vivid they are versus their actual hue, rather than lumping everything into one aggregate ΔE number that could hide the real cause.

Not necessarily — the published perceptibility bands, imperceptible below 1, perceptible on close inspection up to 2, obvious past 3.5, are general rules of thumb rather than universal thresholds. Real acceptance limits depend on your specific product: a trained QC panel can catch subtle browning shifts well under ΔE 2, while natural batch-to-batch variation in some foods can exceed 3 without a typical consumer noticing on the shelf.

The hue angle, the arctangent of b* over a* converted to a 0-360° scale, tells you where each individual sample sits on the color wheel, for example whether it reads more red-orange or more yellow, which the ΔH difference alone can't show. Reporting both hue angles lets you confirm the samples are even in the same general color family before treating a small ΔH as a minor shade variation rather than a fundamentally different hue.