The determination and correction of errors in surface colour measurement

A harmonisation process co-ordinated by the National Physical Laboratory (NPL) was set up to reduce errors in colour measurements with a target such that 95% of the results should agree to within 0.5 CIELAB colour difference units (DeltaE*(ab)). Nine laboratories took part in the harmonisation; some were national laboratories and the rest commercial organisations. The techniques for determining and correcting errors in colour measurements are described. Thirteen sources of error were identified, ten of which were corrected for. Although not all the possible errors for the measurement of colour have been addressed 93% of the measurements agreed to within 0.5 DeltaE*(ab).