Improving the color quality evaluation of holographic prints with light pillars

In order to study the influence of color difference contributed by different lightness, chroma, and hue differences on the human visual perception, 84 pairs of holographic prints from nine cigarette packaging products within 3.0 CIELAB color difference units were prepared. A color difference evaluation experiment was carried out by 22 experienced observers. The results indicated that the observers were more sensitive to hue differences in comparison to the lightness and chroma differences. In addition, the parametric factor and the power function optimization method were made on the standard CIELAB and the CIEDE2000 formulas with the combined 264 pairs of holographic prints, including 180 pairs of samples in the previous studies, in terms of the STRESS (standardized residual sum of squares) index. The results indicated that the optimized factors in CIELAB and CIEDE2000 formulas are k_L: k_C: k_H =1: 1: 0.32 and k_L: k_C: k_H= 1: 1: 0.34, respectively. Therefore, the ΔH*_ab tolerance of 0.8 (for colorized samples) and 0.3 (for achromatic samples), as well as the ΔH₀₀ tolerance of 0.54 (for colorized samples) and 0.4 (for achromatic samples) were recommended for the evaluation of holographic prints with light pillars, especially within the color difference of 3.0 CIELAB units.