To improve a color reproducibility to a reference color by maintaining a good color reproducibility to the reference color even if an ink discharge weight varies among printers, and by maintaining the good color reproducibility to the reference color even if a lot of ink changes.

An object dot distribution table 14c which regulates a color correction corresponding relation between input gradation data and output gradation data is formed so as to compensate a gap of an amount of ink adhered on a printing medium by an object printer to an amount of ink adhered on the printing medium by an ink amount reference printer, and also to compensate a color shift of a patch P2 for color compensation of a dot formation amount of a standard printed on the printing medium when an object ink of a using object of the object printer is used to a reference patch P1 of the dot formation amount of the standard printed on the printing medium when a reference ink is used by an ink comparison reference printer for comparing coloring of the ink.

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