1. A display device comprising a plurality of pixels, wherein in each pixel, a plurality of subframe periods are provided in one frame period, and a gray level of the pixel is expressed in accordance with a time integration level of instantaneous luminances expressed in the plurality of subframe periods, wherein the time integration level is increased as a level of gray level data of the pixel is higher, wherein the time integration level is increased as an average value of gray level data of an original image is smaller, and wherein the plurality of subframe periods are equal in length.