A head-mountable display comprises a frame which is configured to be mounted on a users head, a camera (600) mounted on the frame for capturing a view of the users eyes, a motion detector (610) for detecting motion of the head mountable display device and for generating a motion signal representing a movement of the head mountable display with respect to time, and a controller. The controller is configured to estimate a distance Dr between the users eyes by capturing a relative separation of the users eyes from an image of the users eyes captured by the camera at a start position, to process a motion period of the motion signal corresponding to a process in which the user moves the head mountable display from the start position (900) to dispose the head mountable display on the users head at an end position, and to estimate a displacement of the users eyes with respect to the frame by determining a distance Dx from the start position of the head mountable display at which the image of the users eyes was captured to the end position in which the head mountable display is disposed on the users head. The head mountable display can be arranged therefore to adjust a relative position at which a first image is displayed to one of the users eyes and position at which a second image is displayed to the other of the users eyes in accordance with the estimated distance between the users eyes so as to provide an improved viewing experience.Linvention concerne un afficheur facial, comportant une monture configurée pour être montée sur la tête dun utilisateur, une caméra (600) montée sur la monture pour capter une vue des yeux de lutilisateur, un détecteur (610) de mouvement servant à détecter un mouvement du dispositif dafficheur facial et à générer un signal de mouvement représentant un mouvement de lafficheur facial en fonction du temps, et une commande. La commande est configurée pour estimer une distance Dr entre les yeux de lutilisateur en captant un écartement relatif des
