An image processing apparatus includes a hue identifying unit that identifies to which hue region among three or more hue regions provided in a color space a hue of each pixel contained in input image data belongs; an output-color converting unit that converts a color of each pixel to a predetermined output color in accordance with the identified hue region; a luminance calculating unit that selects a luminance calculation coefficient corresponding to the identified hue region of each pixel from among luminance calculation coefficients determined for the respective hue regions, and calculates luminance to be applied to each pixel of image data converted to the output color, on the basis of the selected luminance calculation coefficient; and an image-data generating unit that applies the calculated luminance to each pixel in the converted image data to generate color-reduced image data containing a reduced number of colors than the input image data.