The present invention extends an entire reproducible gamut by generating color separation data effectively utilizing the particularly high saturation and lightness of a particular color ink. Color separation data uses three types of inks including a particular color ink red and basic color inks yellow and magenta at the maximum saturation point of a hue R. On a low-lightness side with respect to the maximum saturation point, a reproducible color space can be extended by adding a cyan ink or the like to the above inks. In a high-lightness are, the reproducible color space can be extended by using the particular color ink red. Further, the entire gamut of a low-lightness side of this hue can be extended.