An image processing apparatus generates color conversion data in which first color component values in a first color space are associated with second color component values in a second color space. The apparatus executes determining a reference curve that takes a maximum value in the second color space among curves representing gradations of color components in the first color space; determining interpolation guide curves that represent a maximum gradation and a minimum gradation of a color component to be interpolated in the first color space; executing colorimetry on color patches corresponding to second color component values in the reference and interpolation guide curves; interpolating second color component values not included in the reference and interpolation guide curves, based on the second color component values obtained by the colorimetry; and generating the color conversion data by using the second color component values obtained by the colorimetry and the interpolation.