Skin Color Measurement Using Trichromatic LEDs

Skin color has routinely been measured using a contact type colorimeter with a white light source such as a xenon lamp. However, it is difficult to reduce the weight of the apparatus due to its structure, and compression of the skin during colorimetry tended to induce changes in skin blood flow or morphological changes in the skin surface, resulting in measurement errors. Therefore, a colorimeter appropriate for colorimetry of the skin has been needed. We have developed a small light colorimeter (RGB sensor) using LEDs with the three primary colors (red, green and blue) as a light source. Comparison of colorimetric accuracy (color chips and actual skin color) between this sensor and the conventional contact type colorimeter revealed a high correlation (skin color chips: L*, R = 0.999; a*, R = 0.998; b*, R = 0.996. skin color L*, R = 0.921; a*, R = 0.892; and b*, R = 0.885). These results suggest that this small lightweight RGB sensor is as efficient and accurate as the conventional colorimeter, and appropriate for measuring skin color.