肌色評価の信頼性向上：カラーキャリブレーションを用いたフルフェイス撮像デバイスの研究

Skin colour measurement is common and essential to clinical evaluation, especially for product efficacy evaluation and research on skin tone and pigmentary disorders. Among multiple evaluation methods, full-face imaging analysis has become increasingly valuable thanks to attractive visuals, trackability, algorithm optimization, etc. Today, numerous imaging devices are available on the market, employing diffuse light or cross-polarized light. While most systems control their light source output during manufacturing, lack of precise colour calibration and variations between devices remain the key barriers for product efficacy evaluation for skin tone.

This research aims to enhance the reliability of colour measurement by validating two representative full-face imaging devices for clinical objective evaluation. Using a ColorChecker during image capture will allow colour calibration to standardized lighting conditions, thus mitigating device-specific variations and improving the reliability of skin colour measurements.

A 4-week clinical study investigated two imaging devices employing different light sources. A ColorChecker was included in each image capture. Initial analysis of each colour patch assessed the inherent colour accuracy and stability of both devices. Subsequently, image colour calibration was applied to standardize colours to a reference colour under standard light source. Further analysis then evaluated whether this calibration improved the devices' capabilities in measuring skin tone.

There is a disparity in the colour measurement capabilities of the two investigated devices. By incorporating a standard ColorChecker within the field of view and implementing image colour calibration through use of a polynomial regression model, colour accuracy and system stability has been enhanced, thus improving the reliability of colour assessment in clinical evaluation and reducing the inconsistencies between devices.

This study offers insights into colour measurement for skin tone evaluation, demonstrating the value of using a ColorChecker and colour calibration to ensure reliable and accurate skin tone measurements.