The color-appearance models haue been vigorously studied in this decade. Using one of such models, M. R. Pointer developed a method for assessing the color reproduction quality of color images. In the present paper, I try to evaluate the respective contribution of hue-, chroma-, or lightness difference formula by Hunt's color-appearance model. Psychological evaluations and statistical analyses are applied by using a set of color prints with different hue-, chroma-, and lightness values. I have found that the relative values of 2.3: 1.0: 2.2 are most appropriate as the weighting factors for hue-, chroma-, and lightness differences in my color difference formula for the color samples so far studied.