The method involves illuminating a T-shaped region (7) and a U-shaped region (8) with a light i.e. variable intensity flash, to cause brightness of hydrolipidic films in the regions, and capturing images of the illuminated regions. Brightnesses of the images of the T-shaped and U-shaped regions in the form of points and puddles are quantified. Lipid content equal to percentage of surface of the puddles is calculated. The T-shaped region and the U-shaped region are separately observed to determine the lipid content of skin of a face. An independent claim is also included for a device for detecting brightness affecting material such as lipid content of hydrolipidic film at a surface of skin, comprising an illuminating unit.
