Table 2. Comparison of L, a* and b* values for images with camera white balance correction.
| L | |||
| Median (IQR) | χ2 (df) | p * a | |
| Spectrophotometer (control) | 62.45 (7.80) | 120.875 (5) | p = 2.474 × 10−28 |
| Photo box | 54.00 (10.75) | ||
| Windowless clinic 1 | 56.00 (12.00) | ||
| Windowless clinic 2 | 65.00 (10.00) | ||
| Windowed clinic 1 | 56.00 (15.75) | ||
| Windowed clinic 2 | 55.50 (12.75) | ||
| a* | |||
| Median (IQR) | χ2 (df) | p * b | |
| Spectrophotometer (control) | 7.00 (5.10) | 239.923 (5) | p = 8.683 × 10−20 |
| Photo box | 22.00 (2.0) | ||
| Windowless clinic 1 | 7.50 (4.0) | ||
| Windowless clinic 2 | 8.00 (4.00) | ||
| Windowed clinic 1 | 10.00 (2.0) | ||
| Windowed clinic 2 | 9.00 (3.0) | ||
| b* | |||
| Median (IQR) | χ2 (df) | p * c | |
| Spectrophotometer (control) | 43.20 (10.68) | 320.036 (5) | p = 9.412 × 10−18 |
| Photo box | 33.50 (5.75) | ||
| Windowless clinic 1 | 20.00 (3.00) | ||
| Windowless clinic 2 | 22.00 (3.00) | ||
| Windowed clinic 1 | 23.00 (3.00) | ||
| Windowed clinic 2 | 22.00 (3.00) | ||
*Significant < 0.05; χ2 = Chi-square statistics; df = degree of freedom, IQR = Interquartile Range
*Kruskal-Wallis one-way test: Parametric assumption not met. Shapiro- Wilk test significant (p < 0.05)
a Post-hoc analysis (Dunn’s test) for L: Null hypothesis rejected (p < 0.001). Spectrophotometer vs all other lighting conditions showed highly significant differences (p < 0.001) except windowless clinic 2 (p = 0.094). No significant differences observed for photo box vs windowed clinic 2 (p = 0.209), photo box vs windowless clinic 1 (p = 0.092), windowless clinic 1 vs windowed clinic 2 (p = 0.667), widowed clinic 1 vs windowed clinic 2 (p = 0.408), windowless clinic 1 vs windowed clinic 1 (p = 0.691)
b Post-hoc analysis (Dunn’s test) for a*: Null hypothesis rejected (p < 0.001). Spectrophotometer vs all other lighting conditions showed highly significant differences (p < 0.001). No significant differences observed for windowless clinic 1 vs windowless clinic 2 (p = 0.646), windowed clinic 1 vs windowed clinic 2 (p = 0.127)
c Post-hoc analysis (Dunn’s test) for b*: Null hypothesis rejected (p < 0.001). Spectrophotometer vs all other lighting conditions showed highly significant differences (p < 0.001). No significant differences observed for windowed clinic 2 vs windowless clinic 2 (p = 0.663), windowed clinic 1 vs windowed clinic 2 (p = 0.483), windowless clinic 2 vs windowed clinic 1 (p = 0.790)