## 3 Results and Discussion
### Characterizing the Color Appearance of Carpets under Different Illuminants
#### 3.1.2 Illuminant 02: Incandescent (A/10)  
To some extent, similar observations were recorded while measuring the lightness-darkness (L*), redness-greenness (a*), and yellowness-blueness (b*) values under incandescent (A) illuminant (Figure 5). From light to darker shades, decreasing trends were observed for L*, a*, and b* values (Figure 5a-e), with a slight exception in b* values for green-dyed carpets (Figure 5f). Both positive and negative values were observed for b* values, indicating a yellow or blue hue, respectively. As the green wavelength region is neighboring both the yellow and blue wavelength regions in reflectance spectra (Figure 6), such can be expected. However, the chroma values are much lower (\(\mid\pm\)b\(\mid\) ranges between 0-4) compared to other scenarios, indicating very little reflection of the yellow/blue associated wavelengths.  
Figure 5: CIE L*, a*, and b* values for A/10 illumination of different carpets dyed in different shades of red and green color (**a**) L* values for red-colored carpets (**b**) L* values for green-colored carpets (**c**) a* values for red-colored carpets (**d**) a* values for green-colored carpets (**e**) b* values for red-colored carpets (**f**) b* values for green-colored carpets.  
Similar to D65/10, for red-colored carpets, variation in L* values under A/10 illuminant was insignificant (\(p>0.05\)) for all the shades due to the carpet features (Figure 5a). For green-colored carpets, light shades show significant (\(p\leq 0.05\)) variations among the carpets (Figure 5b). The distinction between carpets becomes more prominent with high lightness values (L*) due to the surface characteristics (horizontal yarn availability in the loop arch) facilitating more reflection of incident light in all wavelength ranges, as previously discussed. Similarly, for red-colored carpets, redness-greenness (a*) and yellowness-blueness (b*) values showed significant (\(p<0.05\)) variations for carpets in the dark shade (Figure 5c,e). For darker shades, more concentration of colorant molecules (Table 5) in the dye bath, which subsequently transferred in the loops' reflective surface, will absorb more incident light and reflect corresponding hue light more efficiently. Hence, the hue distinction (variation in chroma) will become more evident for carpet features. For green-colored carpets, redness-greenness (a*) values showed significant (\(p<0.05\)) variation from carpet to carpet in the dark shade (Figure 5d), while light and medium shades showed significant distinction (\(p<0.05\)) between carpets in b* values (Figure 5f). As previously mentioned, a higher concentration of colorant molecules efficiently distributed in the carpet loops will result in facilitated hue distinction from a gradual increase of shading. However, for lower chroma values (0-10), such significant results will be disregarded due to the higher light absorption in all the wavelength regions. Aside from green-colored carpets on the CIE b scale, carpet 3 showed the highest lightness (L*), redness-greenness (a*), and yellowness-blueness (b*) values in significant cases (\(p<0.05\)), while carpet 2 showed the lowest values. Such is related to the light scattering and reflections' efficiency. Carpet structure facilitated less scattering (less twisted yarn in loops or less uneven loops) and more reflection (more smooth yarn in the loop's horizontal surface) which resulted in higher correspondent values. However, with lower values of chroma for the nondominant color reflection \(\mid\pm\)b\(\mid\), such effects will be convoluted due to very little reflection of the corresponding color-associated wavelengths.