The invention provides a new display device and a display method. When image data is sent from a processor to a display unit, the image data is divided into more than two parts such as a photographicpicture part and another part, and corresponding compressed data is generated by performing a suitable compression processing. The total size of each of the compressed data is reduced and is thus preferential to be sent to a display unit. Each of the compressed data is decompressed by a display driver, thus becoming decompressed data. Each of the decompressed data is used for display by the display unit. Other than numerical operation, a display unit having a reflective pixel and a self-luminous pixel may be used to combine the decompressed data.