An operating method of an AR glass apparatus includes obtaining a preview image through a camera of the apparatus, tracking a gaze direction of a user wearing the apparatus, determining an object of interest in the preview image based on the tracked gaze direction, obtaining local motion information indicating a movement of the object of interest by tracking the movement of the object of interest, measuring a movement of the apparatus, obtaining global motion information indicating a movement of a background region included in the preview image based on the measured movement of the apparatus, adjusting a degree of exposure based on the local motion information and the global motion information, and photographing a front of the apparatus through the camera having the adjusted degree of exposure.