A pixel structure including a pair of first sub-pixels, a pair of second sub-pixels and an electrical tunable photonic crystal layer is provided. The pair of first sub-pixels are substantially identical in area, and the pair of second sub-pixels are substantially identical in area. The area of each second sub-pixel is twice the area of each first sub-pixel. In addition, the electrical tunable photonic crystal layer is disposed over the pair of first sub-pixels and the pair of second sub-pixels.