An image processing apparatus is disclosed. The image processing apparatus includes a color conversion processing unit which obtains CMY data from input color space coordinate data of image data, and an output data generating unit which generates output data by forming CMYK data by using a result output from a color conversion processing section. The color conversion processing section includes an optimum color reproduction data structure which gives the CMY data for obtaining a full color image optimally reproduced from the input color space coordinate data, and a color material using amount reducing data structure for outputting the input color space coordinate data by reducing the color material using amount with the use of a reference value in which the color material using amount is increased for a hue of an output image giving a high psychological effect and is decreased for a hue of the output image giving a low psychological effect.