TAPPI T 515 om-20描述了光源的光谱、光度和几何特征、照明和观察条件，以及用于视觉评估纸张色差（包括含有荧光增白剂的纸张）的程序。该方法规定了为实现三个目标而选择的光源:模拟最终使用的实际和照明条件，使用光谱上非常不同的两个光源，以夸大样品和标准之间的可观察差异（如果存在任何差异），使用紫外线辐射器检测荧光增白剂（FWA）的存在，并评估其对最终外观的影响。 该方法适用于测试人员色觉正常的情况。

TAPPI T 515 om-20 describes the spectral, photometric, and geometric characteristics of a light source, the illuminating and viewing conditions, and the procedures to be used for the visual evaluation of color differences of paper, including those containing fluorescent whitening agents.This method specifies light sources which are selected to accomplish three objectives:simulation of the actual and illuminating conditions of ultimate use,employment of two light sources which arespectrally very different in order to exaggerate observable differences between sample and standard if any difference exists, andemployment of a UV radiator to detect the presence of fluorescent whitening agents (FWA) and assess their impact on final appearance.This method is applicable when the testers have normal color vision.