Table 4. Comparison of L, a* and b* values for images with post processing white balance correction using Macbeth color chart.
| L | |||
| Median (IQR) | χ2 (df) | p* a | |
| Spectrophotometer (control) | 62.45 (7.80) | 16.904 (4) | p = 0.000 |
| Windowless clinic 1 | 64.45 (9.60) | ||
| Windowless clinic 2 | 63.00 (7.38) | ||
| Windowed clinic 1 | 62.00 (11.15) | ||
| Windowed clinic 2 | 62.70 (13.25) | ||
| a* | |||
| Median (IQR) | χ2 (df) | P* b | |
| Spectrophotometer (control) | 7.00 (5.10) | 8.933 (4) | p = 0.015 |
| Windowless clinic 1 | 6.75 (4.15) | ||
| Windowless clinic 2 | 6.60 (3.43) | ||
| Windowed clinic 1 | 6.80 (3.10) | ||
| Windowed clinic 2 | 6.80 (3.30) | ||
| b* | |||
| Median (IQR) | χ2 (df) | P* c | |
| Spectrophotometer (control) | 43.20 (10.68) | 205.699 (4) | p = 8.376 × 10−16 |
| Windowless clinic 1 | 20.05 (3.58) | ||
| Windowless clinic 2 | 19.80 (3.20) | ||
| Windowed clinic 1 | 21.70 (3.38) | ||
| Windowed clinic 2 | 21.85 (3.25) | ||
*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 = 0.002). Spectrophotometer Vs all other lighting conditions showed no significant differences (p > 0.05) except windowless clinic 1 (p < 0.001). Additionally, no significant differences observed for windowed clinic 1 vs windowed clinic 2 (p = 0.359), windowed clinic 1 vs windowless clinic 2 (p = 0.115), windowed clinic 2 vs windowless clinic 2 (p = 0.509), windowless clinic 1 vs windowless clinic 2 (p = 0.060)
b Post -hoc analysis (Dunn’s test) for a*: Null hypothesis accepted (p = 0.063)
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 between windowless clinic 1 vs windowless clinic 2 (p = 0.532) and windowed clinic 1 vs windowed clinic 2 (p = 0.953)