Museum Lighting Considering Luminance Distribution of Paintings and Their Surroundings: Examination of Appropriate Brightness Prediction Method Based on Characteristics of Paintings

Paper Presentation in a Themed Session
Miyu Aoyama,  Nozomu Yoshizawa  

In museum lighting, illuminance is commonly used as a metric for displaying pictures. However, the luminance distribution should be considered for the appropriate brightness of the paintings. Brightness can be divided into "brightness perception" and "appropriate brightness". Our previous research revealed that appropriate brightness has a linear relationship with a painting's appearance evaluation and that the brightness perception level that maximises appropriate brightness varies depending on the painting's characteristics. Some paintings are evaluated as more appropriate when brightness levels are relatively low. Ensuring the proper appearance of the paintings with lower light intensities will help protect the paintings from light damage. This study aims to clarify a prediction method of brightness perception that maximises appropriate brightness based on painting characteristics. Subjective experiments were conducted, and 530 experimental conditions were selected from a combination of the following factors: 15 oil paintings, three levels of illuminance on the paintings, ten levels of luminance ratio between the paintings and the background, and three levels of background lightness. The results provided the brightness perception level that maximised the appropriate brightness of each painting. Multiple regression analysis provided a predictive equation with a high coefficient of determination (0.85). The resulting equation included five explanatory variables: mean lightness, lightness difference, mean chroma, chroma contrast, and maximum edge perception. Among them, the lightness difference, chroma contrast, and maximum edge perception significantly determined the brightness perception level that yielded the appropriate brightness.