## 2 Materials and Methods
### Subjective and Objective Trials  
A subjective trial was conducted with 30 participants within the environments of the Cathedral's Museum and the Evangelist Chapel case studies. The study sample comprised 11 men and 19 women, aged between 22 and 36 years. The participants in this study do not exhibit color blindness, and the selected age range was chosen to avoid corneal degradation associated with aging, which can impair the perception of short-wavelength colors. Participants completed a subjective test assessing their satisfaction with color appearance and their preferences regarding the lighting design for each simulated scenario, resulting in a total of 180 surveys. The questionnaire addressed the following issues:  
* What is your level of satisfaction with the color rendering? (very unsatisfied/unsatisfied/neutral/satisfied/very satisfied)
* What is your level of satisfaction with the perception of colors? (very unsatisfied/unsatisfied/neutral/satisfied/very satisfied)
* How do you perceive the hue of the lighting in the space? (very cool/cool/neutral/warm/very warm)  
The results are summarized to complement those observed in the objective trials. It should be noted that respondents' answers may not align with the hue discrimination and color fidelity assessments conducted in the Light Lab, as psychological preferences can differ from objective color perception, as deduced from previous studies [33].  
Figure 8: Multichannel LED system installed in the Light Lab: sequence of CCT variation: 2700 K, 3000 K, 3500 K, 4000 K, 5000 K, and 6500 K.  
The objective trials consisted of two distinct tests designed to evaluate the observer's ability to distinguish similar hues and to assess the color fidelity of a sample under a SPD produced by a specific light source. A description of each test is provided below:  
1. The Farnsworth-Munsell 100 Hue test employs 100 color caps with similar hues in four color ranges with low chromaticity (red to yellow, yellow to green, green to blue, and blue to red), as shown in Figure 9A. Participants must arrange the color caps according to their hue similarity, considering that color references are fixed at both ends of each range. Both the hue caps and light sources were randomly selected for each test and participant. This trial provides an objective measure of a light source's ability to distinguish similar colors. The test score is determined by the number of color cap transpositions; specifically, a light source causing one transposition in the Farnsworth-Munsell trial would receive an error score of 4, two transpositions correspond to an error score of 8, three transpositions to a score of 12, and so on [29].
2. The Natural Color System test utilizes a collection of color samples with varying parameters of chromaticity and brightness, identified in polar coordinates. The hues vary according to the angle, similar to the ranges in the previous test (yellow to red, red to blue, blue to green, and green to yellow), as shown in Figure 9B. Participants must identify the position of the color samples in the polar coordinates. An angular variation indicates a change in hue perception, while a variation in the parallels indicates a change in chromaticity. This test determines the observer's divergence in perceived color from the real one under an illuminated scenario with a particular spectral distribution, and thus assesses the color fidelity allowed by a specific light source.