Color-corrected dermoscopy for objective skin color measurement

Objective skin color measurements are useful to measure disease progression and ensure clinical trials enroll diverse participants. Colorimeters derive color measurements in the L*a*b* color space but can be difficult to use at certain sites. The L*,b* plane is useful for calculating the Individual Typology Angle (ITA), which is used to quantify melanin content. Photography has been considered a tool for colorimetry but has been limited in maintaining color consistency. Therefore, we utilized a dermatoscope, a polarized 10x magnified epiluminescence imaging device, with a 9.5x5.6mm 30-color calibration target for color correction. For 23 subjects with various pigmentation, ITA from -52° to 65°, the ITA was calculated from corrected and uncorrected images and compared to ITA from a Konika Minolta CM700d spectrophotometer. The mean error for corrected ITA values was lower than uncorrected and had a stronger correlation to measured ITA indicating the feasibility of color-corrected dermatoscope as a colorimeter.