印刷图像颜色复制质量的主客观评价

Color Reproduction Quality Metric of Printing Images Based on the Subjective and Objective Evaluations

为了对印刷复制品的颜色质量进行有效评价,实验从图像对儿比较的主观评价方法和S-CIELAB颜色质量判据的客观评价方法两方面对印刷复制品与其原稿的颜色刚可辨差异进行了研究。对一个印刷图像,分别模拟青、品红、黄、黑墨量的改变,共形成了53对儿偏色图像,由主观评价确定了每对儿图像颜色差异的认知几率,以及所对应的客观S-CIELAB平均色差值ΔEs,并将两者建立了对应关系。实验结果表明,如果将认知几率为0.9的图像差异定义为刚可辨差,则对所实验图像,客观的刚可辨差ΔEs为1.4,可视为印刷复制的颜色保真度阈值。

The just-perceived color difference in a pair of printing images, the reproduction and its original, has been confirmed, subjectively by a paired-comparison psychological experiment and objectively by the S-CIELAB color quality metric. For one color image, a total number of 53 pairs of test images, simulating a number of varieties in C, M, Y, and K ink amounts, were produced, and determined their corresponding color difference recognizing probabilities by visual paired-comparison. Also, the image color difference △Es values, presented in the S-CIELAB model, for each pairs of images were calculated and correlated with their color difference recognizing probability. The results showed that the just-perceived image color difference △Eab, when 0.9 color difference recognizing probability being considered as the just-perceived level, was about 1.4 △Eab units for the experiment image, being the image color fidelity threshold parameter.