## 2 Experiment
### Museum Lighting Environment  
This experiment adopts lighting environment parameters of three museums to study the factors affecting psychological perception via different lighting methods (Only the lighting environment and typical paintings and background were evaluated). [PERSON] et al. studied the effects of illumination on inorganic pigments used in traditional paintings, they think that high illuminance could be a problem for some museum objects including textiles, tempera paints, etc. [18]. It selected 31 observers, aged 20-24 years. The first museum is the national museum of western art Figure 2a. The measuring is the painting exhibition room of the 19 th-20 th century. The illuminance is direct illuminance, CCT = 2079 K, x = 0.5239, y = 0.4208, colour rendering index Ra = 96, R9 = 92, average illuminance Eav = 84 lx. The second museum is the Aichi art museum Figure 2b. The measuring is the permanent exhibition room. The illuminance method is indirect illuminance, CCT = 2960 K, x = 0.4409, y = 0.4073, colour rendering index Ra = 90, R9 = 46, average illuminance Eav = 115 lx. The third museum is the [PERSON] art museum Figure 2c. The measuring is the painting exhibition room on the fifth floor. The lighting method is mixed lighting, CCT = 3568 K, x = 0.4130, y = 0.4196, colour rendering index Ra = 93, R9 = 88, average illuminance Eav = 538 lx. The parameters of CCTs and illuminance in the three lighting environment experimental spaces is within [PERSON]'s rule [19]. CCTs analysis of the three lighting environments is shown in Figure 3. The first and second lighting environments CCT light color slant yellow, giving us a warm feeling. The CCT of the third lighting environment is white, which is a warm white light. CRI analysis of the three lighting environments is shown in Figure 4. The R9 of the three art museums is 46, 92 and 88. CCTs, x and y are used to describe the CIE1931 chromaticity. The three spaces use different light sources and spectra, this method is used to define and quantify the parameters of the art museum lighting environment. And the CCTs in art museum lighting is different, which brings different visual experience and feeling to the observer. The lower the CCT, the warmer the hue of the art museum space; the higher the CCT, the cooler the hue of the art museum space and different CCTs give different subjective feelings. In order to accurately represent the colour of the lighting environment. The study uses the x and y values to give the position of the Correlated colour temperatures (CCTs) in CIE1931 accurately and provide more detailed optical data. Figure 2: Three museum lighting environments. (**a**) The national museum of western art. (**b**) The Aichi Prefectural museum of art. (**c**) The Yamazaki Mazak museum of art. The R9 is a very important evaluation index for museum lighting. R9 is saturated red, it is an indicator of the ability of the light source to restore the redness of the object. The larger the value of R9, the higher the ability of the light source to reduce the redness of the object. The LED light source used in most museums is blue light to excite yellow phosphors to emit light. The value of the red light spectrum in the spectrum of this light source is relatively low, but the red spectrum is important in the lighting of art museums, the R9 value was used as an important indicator of evaluating the quality of the lighting environment. People have maintained close ties with architecture. The size of the space inside a building also determines whether the lighting environment is comfortable for us. Good lighting design is inseparable from understood its architectural and space environment. The research classified the types of space, lighting and exhibits of three art museums. This type of research approach can be better defining the lighting environments of the space and exhibits.