Perception and measurement of the whiteness of papers with different gloss and FWA amount
Perception and measurement of the whiteness of papers with different gloss and FWA amount
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发表时间：
2009
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通讯作者：
L. G. Coppel
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作者：
L. G. Coppel
通过对具有不同色调和光泽度的纸张的量值估计和成对智慧测度，评价了平均光泽度对感知白度的影响。将样品印刷在不同光泽度的基材上，以在具有5000 K相关色温的光室照明下测量目标L*a*B* 值。观察者能够在5000 K照明下和在相同的照明下用额外的UV灯对具有大的平均光泽度差异的样品的白度进行评级。CIE白度方程能较好地预测两种光照下的感知白度，平均光泽度对感知白度无显著影响。这意味着CIE白度方程可以用来比较具有非常不同的平均光泽度的纸张的感知白度。然而，由于纸张中荧光增白剂（FWA）的量不同，感知白度预测仅在与视觉评价相同的照明下进行时才有效。使用荧光灯管的典型室内照明比D50或Cilluminants包含更少的紫外线。由于平均光泽度和仪器几何形状导致的仪器白度差异与照明的UV含量的影响相比是明显的。
The effect of mean gloss level on perceived whiteness was evaluated by magnitude estimation and pair wisecomparison of papers with varying shades and gloss levels. The samples were printed on substrates ofdifferent gloss to target L*a*b* values measured under a light booth illumination having a 5000 K correlatedcolour temperature. Observers were able to rate the whiteness of the samples with large mean glossdifferences in the 5000 K illumination and in the same illumination with an additional UV lamp. The CIEwhiteness equation predicted well the perceived whiteness in both illuminations and the mean gloss level hadno significant effect on perceived whiteness. This means that the CIE whiteness equation can be used tocompare the perceived whiteness of papers having very different mean gloss levels. However, due to thedifferent amount of fluorescent whiteness agents (FWA) in the papers, the perceived whiteness predictionwas only valid when the measurement was performed under the same illumination as for the visualevaluations. Typical indoor illumination with florescent light tubes contains much less UV than the D50 or Cilluminants. The instrumental whiteness differences due to mean gloss and instrument geometry werenegligible compared to the effect of the UV content of the illumination.