Abstract: The dark part of the gamut includes switching regions from light color materials to dark color materials, thus preferable results of colors of these regions cannot be obtained by color prediction based on interpolation. Hence, patches of grid points for dividing an input color space are printed on a medium, and the colorimetry results of the patches are obtained. Patches of some of the grid points and an additional point between these grid points are printed on a medium of the same type as the medium, and the colorimetry results of the patches are obtained. The colorimetric value of the additional point is interpolated based on those of grid points around the additional point in the first colorimetry using, as weights, the distances on the color space between the colorimetric value of the additional point and those of the grid points around the additional point in the second colorimetry.