This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for enhancing display viewability in high ambient conditions without excessive increase in power consumption. In one aspect, a controller associated with the display device can be configured to obtain an indication of ambient light conditions from an ambient light sensor or from a host device hosting the display device. Upon receiving an image frame, the controller can derive a set of color subfields and determine a bit-depth value for each color subfield based on the obtained indication of current ambient light conditions and mapping data which maps ranges of ambient light to respective bit-depth values on a color subfield by color subfield basis. The controller can then generate a number of subframes for each color subfield based on the respective determined bit-depth value and cause the generated subframes to be displayed.