A pixel array includes a plurality of repeating units. Each repeating unit includes three first color sub-pixels, three second color sub-pixels, three third color sub-pixels, and three fourth color sub-pixels. The size of one of the first color sub-pixels is greater than the size of each of the other two first color sub-pixels. The size of one of the second color sub-pixels is greater than the size of each of the other two first color sub-pixels. The size of one of the third color sub-pixels is greater than the size of each of the other two third color sub-pixels. The size of one of the fourth color sub-pixels is greater than the size of each of the other two fourth color sub-pixels.