## 3 Results and Discussion  
To analyse the influence of a specific light-shaping attachment on the light emitted from the light source, we calculated the differences in colour rendering index (CRI) for 14 test colour samples (TCS)--between the measured CRI values per TCS for the original light source and its combination with a specific light modifier. Prior to analysing the results in detail, we determined the statistical significance of light sources, light modifiers, TCS, and their pairs on the obtained results. The outcomes of the ANOVA statistical analysis are shown in Table 3.  
Figure 4: Scheme of the test setup, where the spectrophotometer is connected to the Argyll software and set to measure the light emitted from the light source in various tested combinations. According to the \(p\)-value from Table 3, we can assess the light sources, light modifiers, and TCS as significant influencing factors on the calculated CRI differences, along with the interactions between light sources and light modifiers, as well as between light sources and TCS. The interaction between light modifiers and TCS was found to be statistically non-significant, indicating that these factors do not interact with each other in influencing the results and suggesting that the effects of light modifiers and TCS are independent of each other. However, we assume that the sample size is too small (two samples within a group, one per light source) to detect the interaction effects and therefore cannot confirm this thesis. Furthermore, an identical range of degrees of freedom is observed in the residual results, indicating an unexplained variance of a similar nature, as this range can only be achieved by chance or by combining light modifiers and TCS. The F-ratio for light sources (68.43) highlights the significant influence of different light sources on CRI differences. However, the larger sum of squares associated with light modifiers (177.22) suggests that these modifiers contribute more to the overall variability in the CRI differences. This indicates that while light sources have a notable effect on the outcome, light modifiers play a more substantial role in explaining the observed differences in the results. When considering the combined effect of light sources and light modifiers, the impact on the variability in the CRI difference is even more pronounced. This is evidenced by the higher F-ratio of 14.12 and the larger sum of squares of 506.05 associated with the interaction between these two factors. To further examine how these two individual factors influence the results, we averaged the CRI difference values of the 14 test colour samples for each tested combination of light sources and light modifiers. The averaged values of differences per light-shaping attachment are shown in Figure 5, where the results for the xenon light source are shown in subplot (a) and for halogen light in subplot (b). Positive values in Figure 5 indicate that the use of the tested light-shaping attachment produces higher CRI values across the spectra than the original light itself, while negative values result in a lower quality of the reproduced colours. The red background in Figure 5a shows the difference value below \(-1.78\), which indicates the threshold below which the averaged CRI data would be below 95 and the tested combination would be categorised as a non-professional light source. The threshold for halogen light sources would be \(-3.97\), but none of the results show values below this threshold. If we compare the results from Figure 5a with the results in Figure 5b, it becomes clear that not all light modifiers influence the colour properties of the original light in the same way. In general, we can observe an inverse relationship: any combination of a light-shaping attachment with a xenon light source will produce results with opposite values when coupled with a halogen light source. There are exceptions to this observation, such as the use of snoot and a Quadralite stripbox light-shaping attachment.