Method includes: (one) be placed in user head attachment include at least one brightness calibration element at least two contrastes attack region (2) capturing on the head and attachment of the user in image has device (3) the image one sees in front of a mirror is a virtual image brightness calibration element is determined, the attachment is in captured image Determining measured value, (pictorial element or image position of a part of brightness calibration of the brightness of step d) are in close to brightness calibration element (5) modification parameter adjusts the function of the measured value of device under the conditions of optical camera, to improve the calibrating element in the contrast contraste area of image (step f) captures another image and modified parameter to adjust optical acquisition condition (gram) determines that required geometry/appearance installation parameter is based on other images.
