S-CIELAB: A Spatial Extension to the CIE L*a*b* DeltaE Color Difference Metric S-CIELAB is an extension of the CIE L*a*b* DeltaE color difference formula. The extension is in the form of a spatial pre-processing step that incorporates the pattern-color sensitivity measurements by Allen Poirson and Brian Wandell . For more details, please see below. Introduction to S-CIELAB Walk through the Matlab