The invention relates to the cosmetic use of a compound chosen from the compounds of formula and the salts of same as an agent for depigmenting the skin andor keratinous appendages. A predefined amount of electrical energy is supplied to the coil. The system further comprises at least one X-ray detecting media configured to convert the X-ray radiation transmitted through the object to optical signals. These peaks are then analyzed with a histogram method to detect rotation and scaling of the host media signal.