A light source emits a light having a luminance. A light source luminance decision unit determines the luminance for a frame of the image based on pixel values of the frame. A conversion unit converts each pixel value of the frame in correspondence with the luminance. A light modulation unit displays the image by modulating a transmittance or a reflectance of the light based on each converted pixel value of the frame. A selection unit selects a timing to change the luminance in a display period of the frame by comparing the luminance for the frame with a luminance for a previous frame. A control unit changes the luminance of the light source to the luminance for the frame at the timing.