Acceptable color differences for printed color samples

Abstract

Three experiments were carried out to investigate how different parameters affected the color difference evaluations. In each experiment, 450 pairs of printed samples, with the chromaticities surrounding nine CIE recommended color centers, were prepared, and the color difference of each pair was evaluated by a group of observers. The results suggested that the experienced observers were more sensitive to color differences, and the observers were more sensitive to color differences in the standard viewing booth with the directional illumination. The performance of two widely used color difference metrics (i.e., CIELAB and CIEDE2000) was evaluated using the experiment results, and optimizations were then performed on the kL, kC, and kH factors, respectively. It was found that an optimized value of kH in the CIELAB formula and those of kL and kH in the CIEDE2000 formula can significantly improve the performance, suggesting that the observers were much more sensitive to differences in the hue dimension. Threshold values for color difference and hue difference were proposed based on the experiment results. Graphical abstract: [Figure not available: see fulltext.]