An image processing device is provided for processing image data in order to display an image at an image display medium which is capable of displaying white, black, and colors at individual pixels, which are structured by pluralities of sub-pixels. The judgment component acquires the image data and judges whether there is a chromatic color or a non-chromatic color at each pixel. When a pixel is judged to be non-chromatic, the selection component selects a pre-specified black-and-white sub-pixel set in accordance with a gray level of the non-chromatic color. When a pixel is judged to be chromatic, the conversion component converts color data to a sub-pixel set of black and the color in accordance with a pre-specified condition. Of results of conversion, the replacement component replaces a pre-specified sub-pixel set of colors, in an individual pixel or in a pre-specified sub-pixel group, with a pre-specified black-and-white sub-pixel set.