An optical display system includes a first display, a plurality of electronic drivers, a controller, and a combiner. Light from a scene is combined with image light from the first display, and the combined light presented to an observer. The combiner includes an electrochromic layer comprising one or more electrochromic regions separated from each other. The electronic drivers are arranged to electrically connect with and drive respective of the electrochromic regions. The controller is configured to control the plurality of electronic drivers to individually address each of the electrochromic regions to selectively drive some of the electrochromic regions to change light transmission of the selectively driven electrochromic regions.