Method of measuring blemishes on skin

Assessment of the efficacy of compositions to correct imperfections of the skin is an important part of the activity in the development of skin products. One commonly used method for assessment of the blemishes is through use of professional clinical graders. In this method trained clinicians grade the improvement of the skin appearance over extended use of the product. This assessment is subjective and expensive. Thus a method of measuring blemishes on the skin, particularly dark skin, is provided comprising the steps of: (a) acquiring a colour digital image of the skin; (b) selecting either the blue or the green colour channel of the image based on the average colour of the skin; (c) subjecting the selected colour channel to a Gaussian filter operation to obtain an intensity value for each pixel; (d) binarizing the image into pixels of either a black or a white colour using a predetermined threshold intensity value; and (e) counting the number of black pixels.