Comparison of smartphone photography and dermoscope-assisted photography in evaluation of color changes of bruise in forensic patients

Abstract

Background: The dermoscope has been widely developed for enhancing diagnostic capabilities. However, its application within the medicolegal aspect remains limited. This study explored the potential of dermoscopeassisted imaging in improving the bruises assessment for forensic purposes.

Objective: This study aimed to evaluate and compare the efficacy of smartphone photography and cross-polarized dermoscope-assisted photography in assessing bruise color in forensic patients.

Methods: Thirty bruises of varying durations (1 - 7 days) and sizes (1 - 12 cm²) were analyzed in a forensic clinic. Bruises were photographed using a Samsung Galaxy Note 20® with and without a DermliteV® cross-polarized dermoscope (PD) attached. The colorimetric parameters from the color space developed by the International Commission on Illumination (CIELAB), namely, L* (relative luminance), a* (change in red to green) and b* (change in blue to yellow) were measured and color difference (∆E) was calculated. Statistical analyses were conducted to assess the differences of the mean ∆E of the two imaging modalities.

Results: Both modalities demonstrated clear differentiation between normal skin and bruised areas (∆E > 5). The cross-polarized dermoscope showed higher ∆E values for purplish-blue (17.7vs. 14.0, P < 0.001) and yellowish bruises (9.6 vs. 5.4, P < 0.001), indicating superior color distinction. Dermoscope-assisted images exhibited greater consistency and less variability in L*, a*, and b* values, particularly for older or faint yellow bruises.

Conclusion: Cross-polarized dermoscopes enhance bruise visualization and documentation, While smartphones suffice for vivid bruises, dermoscopes are recommended for detailed assessments of faint or older bruise.