A display device includes a display panel unit having predetermined viewing angle characteristics. An image data conversion unit is included that converts original image data to be displayed on the display panel unit so that a luminance difference in a low gray level region does not substantially change between before and after conversion and so that a luminance difference in a high gray level region changes in such a manner that a luminance difference obtained after conversion becomes smaller than a luminance difference obtained before conversion. A data holding unit holds predetermined oblique-view image data corresponding to the predetermined viewing angle characteristics of the display panel unit. An image combining unit combines image data obtained through conversion by the image data conversion unit with the predetermined oblique-view image data to generate composite image data. The composite image data is displayed on the display panel unit.