In order to develop more effective whitening cosmetics, it is necessary to measure the efficacy of the whitening agent objectively. A new quantitative measurement method of stains on the face is called for. We therefore have developed a system in which we measure stains on both an arbitrary part of the face and an arbitarary measure area of that part. We then express the measured values using ITV camera. In this way, we analyze typical brown spots and freckles.
In this system-which we call REMO-STAIN System (Remote stain measurement system)-the face image without stains is processed from original face image using pixel averaging procedure. The Lab value is calculated from the difference between original image and processed image for each pixel. The color defference (dE) is calculated from Lab maps and expressed in mapping expression. We propose that average of dE obtained from REMO-STAIN System be used as the new index of brown spots and freckles.
We analyzed the measurements of typical brown spots and freckles, including senile lentigos (age spots), melasma (liver spots) and ephelides (freckles).