Comparative analysis of smartphone colorimeter apps and spectrophotometry for measuring forehead skin color in maxillofacial prosthesis fabrication.

Purpose: This study aimed to evaluate the accuracy and precision of two smartphone colorimeter apps, Color Grab, and Color Picker, in measuring forehead skin color and to compare their readings with those from a spectrophotometer.

Materials and methods: Fifty participants (26 males, 24 females; median age 23 years, range 21-45) were included. Using a smartphone camera, images of forehead skin were captured, and CIELAB color values were reported by both apps. Measurements from a reference spectrophotometer (MiniScan EZ 4500L, 45°/0° geometry) served as the gold standard. Trueness and precision were assessed using CIELAB and CIEDE2000 formulas. Statistical analyses included one-way ANOVA and Mann-Whitney tests, with significance at p < 0.05.

Results: Both apps showed comparable accuracy in capturing skin color, with absolute trueness (ΔE_Abs) for Color Grab at 7.59 (CIEDE2000) and Color Picker at 7.65. Relative trueness (ΔE_Rel) was 3.79 for Color Grab and 3.70 for Color Picker. Precision (MCDM) demonstrated significant differences between the apps: Color Grab at 1.34 (CIEDE2000) compared to Color Picker at 0.96 (p < 0.0001).

Conclusion: While smartphone apps may not match the accuracy of spectrophotometers, they offer valuable alternatives for color matching in maxillofacial prostheses. Future studies should focus on minimizing systematic errors related to environmental factors and camera settings to enhance measurement accuracy.