Head mounted display

摘要

A head mounted display device comprises an optical combiner that combines light from a display and light from an environment into light transmitted towards a user's eye. A controllable optical element located in the light path from the environment, optically between the environment and the optical combiner, for passing light from the environment switchable between filtering and not filtering by optical blurring or diffusion. The device comprises a camera directed at the environment. A control circuit uses image data from the camera to compute a measure of contrast and/or a measure of luminance in a measurement region within an image or images captured by the camera and applies a control signal to the control input dependent on the measure of contrast and/or the measure of luminance. This is used to create or increase the filtering effect of controllable optical element with an increase of the measure of contrast and/or the measure of luminance.