Research on digital images´ color-difference by altering lightness and chroma: Analysis and evaluation of color-difference formulae

The visual data obtained from the psychophysical experiment by altering lightness and chroma of five different digital images of ISO SCID 400 N2 (Street), N3 (Fruit), N4 (Metal), N5 (Object) and N7 (Musician) were used to test the four classical color-difference formulae, CIELAB, CMC, CIE94 and CIEDE2000 with the weighting coefficients k_L: k_C : k_H =1:1:1 and 2:1:1 respectively, in terms of performance factors of STRESS. The experimental and calculated results with the five digital images totally of 100 image pairs indicated that, compare with the original formulae(k_L: k_C : k_H =1:1:1), the color difference formulae performed better using weighting coefficients k_L: k_C : k_H =2:1:1. CIEDE2000 (2:1:1) color difference formula outperformed the others while CMC(1:1) performed the worst. The performance of the color-difference formulae is better by altering lightness value than by altering chroma value, except the CIELAB color difference-formula. The data also indicated that different images had different sensitivity; the color difference is content-related.