Under the current COVID-19 global pandemic, most of the world is operating online, which has increased the importance of better understanding the perceived color quality of video conference calls. We performed two experiments to evaluate the white balance appearance preference for images simulating a scene from a video conference call where a person is using a virtual background. Due to the dissimilarities of the light sources used for the subject and the background scene, the overall picture may look aesthetically unappealing. The first experiment was designed to assess the preference of white balance for images containing a foreground subject, with three different skin tones: light, medium, and dark, and a background scene, with five different color temperature appearances, cool to warm. The background scenes include famous attractions in the United States, water bodies, foliage, and a few less common scenes like a sculpture at the Rochester Institute of Technology (RIT) and a ColorChecker. Observers were presented with a pair of images of the same subject with same background scene, but with different white balance appearance. These comparisons were performed for each foreground subject with all background scenes. Both experiments were performed by naïve observers, who were from around the globe with no knowledge of color science and observers from the Munsell Color Science Lab (MCSL) at the RIT. The results show that observers' preference increases as we go from cooler to warmer appearance for the Canyon, RIT, Snow, Flower, and Autumn backgrounds, and vice versa for the Lake background. The Golden Gate background results are the most scattered among all scenes with very small differences in their scale values. MCSL observers show a strong agreement in preference to warmer appearance for light and dark skin tones for the RIT scene, and neutral and warmer appearance for medium skin tone for the RIT and Golden Gate scenes, respectively. To understand the relation between the background scene and foreground subject's white balance appearance, a second experiment was performed. The subjects had three different appearances: cool, neutral, and warm. Based on the results of the first experiment, five scenes with two white balance appearances, the most preferred rendition and the neutral rendition (original appearance at the time of the scene was captured), were used for the second paired comparison study. The results indicated that preference varied based on the foreground subject skin tone and background scene. However, the background preferences follow similar trends to the first experiment. There were variations in the degree of agreement, some showed very strong agreement, like dark skin tone with the RIT background, whereas for others, like autumn background with light skin tone, preferences were more scattered. Overall, the differences in the scale values were smaller as compared to the first experiment, which indicates that, as we present the observers with more options, the decision became harder.

中文翻译：

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使用虚拟背景的应用程序的首选白平衡

在当前的 COVID-19 全球大流行下，世界上大部分地区都在在线运营，这增加了更好地了解视频电话会议感知色彩质量的重要性。我们进行了两个实验来评估模拟视频电话会议中一个人使用虚拟背景的场景的图像的白平衡外观偏好。由于用于拍摄对象和背景场景的光源不同，整体画面可能看起来不美观。第一个实验旨在评估包含前景主体的图像的白平衡偏好，具有三种不同的肤色：浅色、中色和深色，以及背景场景，具有五种不同的色温外观，从冷色到暖色。背景场景包括美国著名景点、水体、树叶，以及一些不太常见的场景，如罗彻斯特理工学院 (RIT) 的雕塑和 ColorChecker。向观察者展示了具有相同背景场景但具有不同白平衡外观的同一主题的一对图像。这些比较是针对具有所有背景场景的每个前景主体进行的。这两个实验都是由天真的观察者进行的，他们来自世界各地，对色彩科学一无所知，而来自 RIT 的孟塞尔色彩科学实验室 (MCSL) 的观察者。结果表明，观察者对峡谷、RIT、雪、花和秋季背景的偏好随着我们从较冷到较暖的外观而增加，反之亦然对于湖背景。Golden Gate 背景结果在所有场景中最为分散，它们的比例值差异非常小。MCSL 观察者强烈同意 RIT 场景的浅色和深色肤色偏暖的外观，以及 RIT 和金门场景的中等肤色偏中性和偏暖的外观。为了了解背景场景和前景主体的白平衡外观之间的关系，进行了第二个实验。受试者具有三种不同的外观：冷、中性和暖。根据第一次实验的结果，具有两种白平衡外观的五个场景，即最喜欢的再现和中性再现（捕获场景时的原始外观），用于第二次配对比较研究。结果表明，偏好因前景主体肤色和背景场景而异。然而，背景偏好遵循与第一个实验相似的趋势。一致性程度存在差异，有的表现出很强的一致性，如深肤色与 RIT 背景，而对于其他人，如秋季背景与浅肤色，偏好较为分散。总体而言，与第一个实验相比，尺度值的差异更小，这表明，随着我们向观察者提供更多选项，决策变得更加困难。喜欢RIT背景的深色肤色，而其他人，喜欢浅肤色的秋季背景，偏好更分散。总体而言，与第一个实验相比，尺度值的差异更小，这表明，随着我们向观察者提供更多选项，决策变得更加困难。喜欢RIT背景的深色肤色，而其他人，喜欢浅肤色的秋季背景，偏好更分散。总体而言，与第一个实验相比，尺度值的差异更小，这表明，随着我们向观察者提供更多选项，决策变得更加困难。