Testing & Quality Control

Colour Difference Delta E & CMC Acceptability Calculator

CMC weights lightness, chroma and hue differently because the eye does. Delta E*ab does not.

Standard Reference shade
Batch Production sample
CMC Parameters Commercial setting
dE

Delta E CMC

— dE

Perceptually weighted colour difference

Difference Components

Delta E*ab (CIE 1976)
— dE
Lightness Difference
— dL
Chroma Difference
— dC
Hue Difference
— dH
Margin Inside Tolerance
— dE

CMC(2:1) is the usual textile setting and tolerates lightness shifts twice as readily as chroma shifts. A negative margin means the batch fails.

Colour Difference Delta E & CMC Acceptability Calculator — free, with the formula and a worked example, at Textile School.