There is described an image processing apparatus that converts (n+m)-bit monochromatic image data of a single channel into n-bit color display image data of three channels or more, based on predetermined correlations. The apparatus includes luminance and chromaticity calculating sections to calculate luminance and chromaticity information corresponding to each of monochrome signal values; a signal value determining section to determine each combination of plural-channel color signal values represented by the n-bit color display image data, based on the luminance and chromaticity information, so that each combination of the plural-channel color signal values corresponds to each of the monochrome signal values; and a correlation establishing section to establish the predetermined correlations between the (n+m)-bit monochromatic image data and the n-bit color display image data, so that each combination of the plural-channel color signal values and each of the monochrome signal values are correlated with each other.