The evaluation of colour difference equations and optimization of DE2000

The original colour difference equation DEab published by the CIE in 1976 built the foundation for modern colour differencing methods. This equation had its imperfections by giving colour difference numbers that do not correlate with the visual impression of colour difference. Through the release of the DE94 and later on the DE2000 colour difference equation the CIE addressed these imperfections. The Colour Measurement Committee of the Society of Dyers and Colorists of Great Britain released the DECMC-colour difference equation. This equation has not been modified since it initial inception in 1984.

With four available colour differencing equations one has to ask oneself which one of these equations correlates better with the way human observers perceive colour differences. In this report 35 colours with 4 variations for each colour were evaluated and ranked by 24 observers. The initial differences were determined under DEab. The rankings given by the observers were weighted and correlated with the DE values calculated with the four colour differencing equations. The correlation values were plotted individually for each equation in respect to Lightness, Hue and Chroma to determine which equation corresponds better with the perceived differences. The DECMC and DE2000 equations corresponded well with the perceived differences with an advantage for DE2000.